diff --git a/DEPS.bzl b/DEPS.bzl
index e11b2cc344fe..1734acb78331 100644
--- a/DEPS.bzl
+++ b/DEPS.bzl
@@ -6043,6 +6043,16 @@ def go_deps():
             "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/mjibson/esc/com_github_mjibson_esc-v0.2.0.zip",
         ],
     )
+    go_repository(
+        name = "com_github_mkungla_bexp_v3",
+        build_file_proto_mode = "disable_global",
+        importpath = "github.com/mkungla/bexp/v3",
+        sha256 = "903a932e83da8be3426e29c1484d79f814a825b2c2743c36d43b054910a9f886",
+        strip_prefix = "github.com/mkungla/bexp/v3@v3.0.1",
+        urls = [
+            "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/mkungla/bexp/v3/com_github_mkungla_bexp_v3-v3.0.1.zip",
+        ],
+    )
     go_repository(
         name = "com_github_mmatczuk_go_generics",
         build_file_proto_mode = "disable_global",
diff --git a/build/bazelutil/distdir_files.bzl b/build/bazelutil/distdir_files.bzl
index 29a3de2bb629..4373a7aaf609 100644
--- a/build/bazelutil/distdir_files.bzl
+++ b/build/bazelutil/distdir_files.bzl
@@ -629,6 +629,7 @@ DISTDIR_FILES = {
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/mitchellh/osext/com_github_mitchellh_osext-v0.0.0-20151018003038-5e2d6d41470f.zip": "d8e6e5f6bd749cfa0c1c17c40f5dc0fd19e4a0a83245f46bde23bea4e65d1a20",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/mitchellh/reflectwalk/com_github_mitchellh_reflectwalk-v1.0.0.zip": "318ab84e22d4554a7540c7ebc9b4fb607e2608578c3a5bb72434203988048145",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/mjibson/esc/com_github_mjibson_esc-v0.2.0.zip": "9f090786bd43dddb5c0d798b449d5e8aede4cb7d106f56dcac0aebd8fd1929cc",
+    "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/mkungla/bexp/v3/com_github_mkungla_bexp_v3-v3.0.1.zip": "903a932e83da8be3426e29c1484d79f814a825b2c2743c36d43b054910a9f886",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/mmatczuk/go_generics/com_github_mmatczuk_go_generics-v0.0.0-20181212143635-0aaa050f9bab.zip": "18c1e95c93f1f82be0184bc13bf49eb4350c7a4ff524b1bf440b3eb9ff14acc9",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/mmcloughlin/geohash/com_github_mmcloughlin_geohash-v0.9.0.zip": "7162856858d9bb3c411d4b42ad19dfff579341ddf0580122e3f1ac3be05c7441",
     "https://storage.googleapis.com/cockroach-godeps/gomod/github.com/moby/locker/com_github_moby_locker-v1.0.1.zip": "f07361346d12a24e168db7fb2f21281883bee6060f1aedf7507bccf20c4a793f",
diff --git a/go.mod b/go.mod
index 1de7caa502f5..56d95a4cf230 100644
--- a/go.mod
+++ b/go.mod
@@ -178,6 +178,7 @@ require (
 	github.com/mattn/goveralls v0.0.2
 	github.com/mibk/dupl v1.0.0
 	github.com/mitchellh/reflectwalk v1.0.0
+	github.com/mkungla/bexp/v3 v3.0.1
 	github.com/mmatczuk/go_generics v0.0.0-20181212143635-0aaa050f9bab
 	github.com/montanaflynn/stats v0.6.6
 	github.com/mozillazg/go-slugify v0.2.0
diff --git a/go.sum b/go.sum
index 469449d816a8..6144688ce2e8 100644
--- a/go.sum
+++ b/go.sum
@@ -1680,6 +1680,8 @@ github.com/mitchellh/osext v0.0.0-20151018003038-5e2d6d41470f/go.mod h1:OkQIRizQ
 github.com/mitchellh/reflectwalk v1.0.0 h1:9D+8oIskB4VJBN5SFlmc27fSlIBZaov1Wpk/IfikLNY=
 github.com/mitchellh/reflectwalk v1.0.0/go.mod h1:mSTlrgnPZtwu0c4WaC2kGObEpuNDbx0jmZXqmk4esnw=
 github.com/mjibson/esc v0.2.0/go.mod h1:9Hw9gxxfHulMF5OJKCyhYD7PzlSdhzXyaGEBRPH1OPs=
+github.com/mkungla/bexp/v3 v3.0.1 h1:UqcWAaxWn+rmJ+3ZgwokMrUerGMUeOFihUPrTLPFZ9Q=
+github.com/mkungla/bexp/v3 v3.0.1/go.mod h1:zkzndAaEcYdZcu+cB4WkNYQuG7pwjzMOZLn3vM8KD+8=
 github.com/mmatczuk/go_generics v0.0.0-20181212143635-0aaa050f9bab h1:QjLgi/L+MjxysinrA8KkNZLf3cAhTluBoSXUvFeN144=
 github.com/mmatczuk/go_generics v0.0.0-20181212143635-0aaa050f9bab/go.mod h1:Fs8p4al9GNa3b42YfZOoUVMdjQ2WlNEYlnoboJKPpJ8=
 github.com/mmcloughlin/geohash v0.9.0 h1:FihR004p/aE1Sju6gcVq5OLDqGcMnpBY+8moBqIsVOs=
diff --git a/pkg/BUILD.bazel b/pkg/BUILD.bazel
index 880a6fc999dd..4cbd339a21ab 100644
--- a/pkg/BUILD.bazel
+++ b/pkg/BUILD.bazel
@@ -205,6 +205,7 @@ ALL_TESTS = [
     "//pkg/kv/kvserver/gc:gc_test",
     "//pkg/kv/kvserver/idalloc:idalloc_test",
     "//pkg/kv/kvserver/intentresolver:intentresolver_test",
+    "//pkg/kv/kvserver/kvflowcontrol/kvflowcontroller:kvflowcontroller_test",
     "//pkg/kv/kvserver/kvstorage:kvstorage_test",
     "//pkg/kv/kvserver/liveness:liveness_test",
     "//pkg/kv/kvserver/logstore:logstore_test",
@@ -1219,6 +1220,8 @@ GO_TARGETS = [
     "//pkg/kv/kvserver/intentresolver:intentresolver",
     "//pkg/kv/kvserver/intentresolver:intentresolver_test",
     "//pkg/kv/kvserver/kvadmission:kvadmission",
+    "//pkg/kv/kvserver/kvflowcontrol/kvflowcontroller:kvflowcontroller",
+    "//pkg/kv/kvserver/kvflowcontrol/kvflowcontroller:kvflowcontroller_test",
     "//pkg/kv/kvserver/kvflowcontrol/kvflowcontrolpb:kvflowcontrolpb",
     "//pkg/kv/kvserver/kvflowcontrol:kvflowcontrol",
     "//pkg/kv/kvserver/kvserverbase:kvserverbase",
@@ -2022,6 +2025,7 @@ GO_TARGETS = [
     "//pkg/util/admission:admission",
     "//pkg/util/admission:admission_test",
     "//pkg/util/arith:arith",
+    "//pkg/util/asciitsdb:asciitsdb",
     "//pkg/util/binfetcher:binfetcher",
     "//pkg/util/binfetcher:binfetcher_test",
     "//pkg/util/bitarray:bitarray",
@@ -2619,6 +2623,7 @@ GET_X_DATA_TARGETS = [
     "//pkg/kv/kvserver/intentresolver:get_x_data",
     "//pkg/kv/kvserver/kvadmission:get_x_data",
     "//pkg/kv/kvserver/kvflowcontrol:get_x_data",
+    "//pkg/kv/kvserver/kvflowcontrol/kvflowcontroller:get_x_data",
     "//pkg/kv/kvserver/kvflowcontrol/kvflowcontrolpb:get_x_data",
     "//pkg/kv/kvserver/kvserverbase:get_x_data",
     "//pkg/kv/kvserver/kvserverpb:get_x_data",
@@ -3123,6 +3128,7 @@ GET_X_DATA_TARGETS = [
     "//pkg/util/admission:get_x_data",
     "//pkg/util/admission/admissionpb:get_x_data",
     "//pkg/util/arith:get_x_data",
+    "//pkg/util/asciitsdb:get_x_data",
     "//pkg/util/binfetcher:get_x_data",
     "//pkg/util/bitarray:get_x_data",
     "//pkg/util/bufalloc:get_x_data",
diff --git a/pkg/kv/kvserver/kvflowcontrol/BUILD.bazel b/pkg/kv/kvserver/kvflowcontrol/BUILD.bazel
index 04ef54d4893d..4817b09ce5a9 100644
--- a/pkg/kv/kvserver/kvflowcontrol/BUILD.bazel
+++ b/pkg/kv/kvserver/kvflowcontrol/BUILD.bazel
@@ -13,6 +13,8 @@ go_library(
         "//pkg/kv/kvserver/kvflowcontrol/kvflowcontrolpb",
         "//pkg/roachpb",
         "//pkg/util/admission/admissionpb",
+        "@com_github_cockroachdb_redact//:redact",
+        "@com_github_dustin_go_humanize//:go-humanize",
     ],
 )
 
diff --git a/pkg/kv/kvserver/kvflowcontrol/doc.go b/pkg/kv/kvserver/kvflowcontrol/doc.go
index f4b1a0ed64a3..285cb16cce1e 100644
--- a/pkg/kv/kvserver/kvflowcontrol/doc.go
+++ b/pkg/kv/kvserver/kvflowcontrol/doc.go
@@ -353,3 +353,5 @@ package kvflowcontrol
 //       the receiver to send messages to return tokens up to some point, and
 //   (b) the receiver has either not received the message for which we've
 //   deducted tokens, or forgotten about it.
+// - Ensure that flow tokens aren't leaked, by checking that after the tests
+//   quiesce, flow tokens are back to their original limits.
diff --git a/pkg/kv/kvserver/kvflowcontrol/kvflowcontrol.go b/pkg/kv/kvserver/kvflowcontrol/kvflowcontrol.go
index 68f2cfa7b3a0..635b946f6b14 100644
--- a/pkg/kv/kvserver/kvflowcontrol/kvflowcontrol.go
+++ b/pkg/kv/kvserver/kvflowcontrol/kvflowcontrol.go
@@ -19,6 +19,8 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/kv/kvserver/kvflowcontrol/kvflowcontrolpb"
 	"github.com/cockroachdb/cockroach/pkg/roachpb"
 	"github.com/cockroachdb/cockroach/pkg/util/admission/admissionpb"
+	"github.com/cockroachdb/redact"
+	"github.com/dustin/go-humanize"
 )
 
 // Stream models the stream over which we replicate data traffic, the
@@ -34,7 +36,10 @@ type Stream struct {
 // Tokens represent the finite capacity of a given stream, expressed in bytes
 // for data we're looking to replicate. Use of replication streams are
 // predicated on tokens being available.
-type Tokens uint64
+//
+// NB: We use a signed integer to accommodate data structures that deal with
+// token deltas, or buckets that are allowed to go into debt.
+type Tokens int64
 
 // Controller provides flow control for replication traffic in KV, held at the
 // node-level.
@@ -136,3 +141,30 @@ type DispatchReader interface {
 	PendingDispatch() []roachpb.NodeID
 	PendingDispatchFor(roachpb.NodeID) []kvflowcontrolpb.AdmittedRaftLogEntries
 }
+
+func (t Tokens) String() string {
+	return redact.StringWithoutMarkers(t)
+}
+
+// SafeFormat implements the redact.SafeFormatter interface.
+func (t Tokens) SafeFormat(p redact.SafePrinter, verb rune) {
+	sign := "+"
+	if t < 0 {
+		sign = "-"
+		t = -t
+	}
+	p.Printf("%s%s", sign, humanize.IBytes(uint64(t)))
+}
+
+func (s Stream) String() string {
+	return redact.StringWithoutMarkers(s)
+}
+
+// SafeFormat implements the redact.SafeFormatter interface.
+func (s Stream) SafeFormat(p redact.SafePrinter, verb rune) {
+	tenantSt := s.TenantID.String()
+	if s.TenantID.IsSystem() {
+		tenantSt = "1"
+	}
+	p.Printf("t%s/s%s", tenantSt, s.StoreID.String())
+}
diff --git a/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/BUILD.bazel b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/BUILD.bazel
new file mode 100644
index 000000000000..eaf9f5c6311b
--- /dev/null
+++ b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/BUILD.bazel
@@ -0,0 +1,55 @@
+load("//build/bazelutil/unused_checker:unused.bzl", "get_x_data")
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "kvflowcontroller",
+    srcs = [
+        "kvflowcontroller.go",
+        "kvflowcontroller_metrics.go",
+    ],
+    importpath = "github.com/cockroachdb/cockroach/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//pkg/base",
+        "//pkg/kv/kvserver/kvflowcontrol",
+        "//pkg/settings",
+        "//pkg/settings/cluster",
+        "//pkg/util/admission/admissionpb",
+        "//pkg/util/buildutil",
+        "//pkg/util/hlc",
+        "//pkg/util/log",
+        "//pkg/util/metric",
+        "//pkg/util/syncutil",
+    ],
+)
+
+go_test(
+    name = "kvflowcontroller_test",
+    srcs = [
+        "kvflowcontrol_token_adjustment_test.go",
+        "kvflowcontroller_simulation_test.go",
+    ],
+    args = ["-test.timeout=295s"],
+    data = glob(["testdata/**"]),
+    embed = [":kvflowcontroller"],
+    deps = [
+        "//pkg/kv/kvserver/kvflowcontrol",
+        "//pkg/roachpb",
+        "//pkg/settings/cluster",
+        "//pkg/testutils/datapathutils",
+        "//pkg/util/admission/admissionpb",
+        "//pkg/util/asciitsdb",
+        "//pkg/util/hlc",
+        "//pkg/util/leaktest",
+        "//pkg/util/log",
+        "//pkg/util/metric",
+        "//pkg/util/timeutil",
+        "@com_github_cockroachdb_datadriven//:datadriven",
+        "@com_github_dustin_go_humanize//:go-humanize",
+        "@com_github_guptarohit_asciigraph//:asciigraph",
+        "@com_github_mkungla_bexp_v3//:bexp",
+        "@com_github_stretchr_testify//require",
+    ],
+)
+
+get_x_data(name = "get_x_data")
diff --git a/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/kvflowcontrol_token_adjustment_test.go b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/kvflowcontrol_token_adjustment_test.go
new file mode 100644
index 000000000000..9bd06ef6f547
--- /dev/null
+++ b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/kvflowcontrol_token_adjustment_test.go
@@ -0,0 +1,159 @@
+// Copyright 2023 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package kvflowcontroller
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/cockroachdb/cockroach/pkg/kv/kvserver/kvflowcontrol"
+	"github.com/cockroachdb/cockroach/pkg/roachpb"
+	"github.com/cockroachdb/cockroach/pkg/settings/cluster"
+	"github.com/cockroachdb/cockroach/pkg/util/admission/admissionpb"
+	"github.com/cockroachdb/cockroach/pkg/util/hlc"
+	"github.com/cockroachdb/cockroach/pkg/util/leaktest"
+	"github.com/cockroachdb/cockroach/pkg/util/log"
+	"github.com/cockroachdb/cockroach/pkg/util/metric"
+	"github.com/cockroachdb/datadriven"
+	"github.com/dustin/go-humanize"
+	"github.com/stretchr/testify/require"
+)
+
+func TestFlowTokenAdjustment(t *testing.T) {
+	defer leaktest.AfterTest(t)()
+	defer log.Scope(t).Close(t)
+
+	var (
+		ctx         = context.Background()
+		controller  *Controller
+		adjustments []adjustment
+		stream      = kvflowcontrol.Stream{
+			TenantID: roachpb.SystemTenantID,
+			StoreID:  roachpb.StoreID(1),
+		}
+	)
+
+	datadriven.RunTest(t, "testdata/flow_token_adjustment",
+		func(t *testing.T, d *datadriven.TestData) string {
+			switch d.Cmd {
+			case "init":
+				controller = New(
+					metric.NewRegistry(),
+					cluster.MakeTestingClusterSettings(),
+					hlc.NewClockWithSystemTimeSource(time.Nanosecond),
+				)
+				adjustments = nil
+				return ""
+
+			case "adjust":
+				require.NotNilf(t, controller, "uninitialized flow controller (did you use 'init'?)")
+
+				for _, line := range strings.Split(d.Input, "\n") {
+					parts := strings.Fields(line)
+					require.Len(t, parts, 2, "expected form 'class={regular,elastic} delta={+,-}<size>")
+
+					var delta kvflowcontrol.Tokens
+					var pri admissionpb.WorkPriority
+
+					// Parse class={regular,elastic}.
+					parts[0] = strings.TrimSpace(parts[0])
+					require.True(t, strings.HasPrefix(parts[0], "class="))
+					parts[0] = strings.TrimPrefix(strings.TrimSpace(parts[0]), "class=")
+					switch parts[0] {
+					case "regular":
+						pri = admissionpb.NormalPri
+					case "elastic":
+						pri = admissionpb.BulkNormalPri
+					}
+
+					// Parse delta={+,-}<size>
+					parts[1] = strings.TrimSpace(parts[1])
+					require.True(t, strings.HasPrefix(parts[1], "delta="))
+					parts[1] = strings.TrimPrefix(strings.TrimSpace(parts[1]), "delta=")
+					require.True(t, strings.HasPrefix(parts[1], "+") || strings.HasPrefix(parts[1], "-"))
+					isPositive := strings.Contains(parts[1], "+")
+					parts[1] = strings.TrimPrefix(parts[1], "+")
+					parts[1] = strings.TrimPrefix(parts[1], "-")
+					bytes, err := humanize.ParseBytes(parts[1])
+					require.NoError(t, err)
+					delta = kvflowcontrol.Tokens(int64(bytes))
+					if !isPositive {
+						delta = -delta
+					}
+
+					controller.adjustTokens(ctx, pri, delta, stream)
+					adjustments = append(adjustments, adjustment{
+						pri:   pri,
+						delta: delta,
+						post:  controller.testingGetTokensForStream(stream),
+					})
+				}
+				return ""
+
+			case "history":
+				limit := controller.testingGetLimit()
+
+				var buf strings.Builder
+				buf.WriteString("                   regular |  elastic\n")
+				buf.WriteString(fmt.Sprintf("                  %8s | %8s\n",
+					printTrimmedTokens(limit[admissionpb.RegularWorkClass]),
+					printTrimmedTokens(limit[admissionpb.ElasticWorkClass]),
+				))
+				buf.WriteString("======================================\n")
+				for _, h := range adjustments {
+					buf.WriteString(fmt.Sprintf("%s\n", h))
+				}
+				return buf.String()
+
+			default:
+				return fmt.Sprintf("unknown command: %s", d.Cmd)
+			}
+		})
+}
+
+type adjustment struct {
+	pri   admissionpb.WorkPriority
+	delta kvflowcontrol.Tokens
+	post  tokensPerWorkClass
+}
+
+func printTrimmedTokens(t kvflowcontrol.Tokens) string {
+	return strings.ReplaceAll(t.String(), " ", "")
+}
+
+func (h adjustment) String() string {
+	class := admissionpb.WorkClassFromPri(h.pri)
+
+	comment := ""
+	if h.post[admissionpb.RegularWorkClass] <= 0 {
+		comment = "regular"
+	}
+	if h.post[admissionpb.ElasticWorkClass] <= 0 {
+		if len(comment) == 0 {
+			comment = "elastic"
+		} else {
+			comment = "regular and elastic"
+		}
+	}
+	if len(comment) != 0 {
+		comment = fmt.Sprintf(" (%s blocked)", comment)
+	}
+	return fmt.Sprintf("%8s %7s  %8s | %8s%s",
+		printTrimmedTokens(h.delta),
+		class,
+		printTrimmedTokens(h.post[admissionpb.RegularWorkClass]),
+		printTrimmedTokens(h.post[admissionpb.ElasticWorkClass]),
+		comment,
+	)
+}
diff --git a/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/kvflowcontroller.go b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/kvflowcontroller.go
new file mode 100644
index 000000000000..69a760d47c59
--- /dev/null
+++ b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/kvflowcontroller.go
@@ -0,0 +1,424 @@
+// Copyright 2023 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package kvflowcontroller
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/cockroachdb/cockroach/pkg/kv/kvserver/kvflowcontrol"
+	"github.com/cockroachdb/cockroach/pkg/settings"
+	"github.com/cockroachdb/cockroach/pkg/settings/cluster"
+	"github.com/cockroachdb/cockroach/pkg/util/admission/admissionpb"
+	"github.com/cockroachdb/cockroach/pkg/util/buildutil"
+	"github.com/cockroachdb/cockroach/pkg/util/hlc"
+	"github.com/cockroachdb/cockroach/pkg/util/log"
+	"github.com/cockroachdb/cockroach/pkg/util/metric"
+	"github.com/cockroachdb/cockroach/pkg/util/syncutil"
+)
+
+var regularTokensPerStream = settings.RegisterByteSizeSetting(
+	settings.SystemOnly,
+	"kvadmission.flow_controller.regular_tokens_per_stream",
+	"flow tokens available for regular work on a per-stream basis",
+	16<<20, // 16 MiB
+	validateTokenRange,
+)
+
+var elasticTokensPerStream = settings.RegisterByteSizeSetting(
+	settings.SystemOnly,
+	"kvadmission.flow_controller.elastic_tokens_per_stream",
+	"flow tokens available for elastic work on a per-stream basis",
+	8<<20, // 8 MiB
+	validateTokenRange,
+)
+
+// Aliases to make the code below slightly easier to read.
+const regular, elastic = admissionpb.RegularWorkClass, admissionpb.ElasticWorkClass
+
+// Controller is a concrete implementation of the kvflowcontrol.Controller
+// interface. It provides flow control for replication traffic in KV and is
+// typically held at the node-level.
+type Controller struct {
+	mu struct {
+		syncutil.Mutex
+
+		// Token limit per work class, tracking
+		// kvadmission.flow_controller.{regular,elastic}_tokens_per_stream.
+		limit tokensPerWorkClass
+
+		// We maintain flow token buckets for {regular,elastic} work along each
+		// stream. This is lazily instantiated.
+		//
+		// TODO(irfansharif): Sort out the GC story for these buckets. When
+		// streams get closed permanently (tenants get deleted, nodes removed)
+		// or when completely inactive (no tokens deducted/returned over 30+
+		// minutes), clear these out.
+		buckets map[kvflowcontrol.Stream]bucket
+	}
+	metrics *metrics
+	clock   *hlc.Clock
+}
+
+var _ kvflowcontrol.Controller = &Controller{}
+
+// New constructs a new Controller.
+func New(registry *metric.Registry, settings *cluster.Settings, clock *hlc.Clock) *Controller {
+	c := &Controller{
+		clock: clock,
+	}
+
+	regularTokens := kvflowcontrol.Tokens(regularTokensPerStream.Get(&settings.SV))
+	elasticTokens := kvflowcontrol.Tokens(elasticTokensPerStream.Get(&settings.SV))
+	c.mu.limit = map[admissionpb.WorkClass]kvflowcontrol.Tokens{
+		regular: regularTokens,
+		elastic: elasticTokens,
+	}
+	c.mu.buckets = make(map[kvflowcontrol.Stream]bucket)
+	regularTokensPerStream.SetOnChange(&settings.SV, func(ctx context.Context) {
+		c.mu.Lock()
+		defer c.mu.Unlock()
+
+		before := tokensPerWorkClass{
+			regular: c.mu.limit[regular],
+			elastic: c.mu.limit[elastic],
+		}
+		now := tokensPerWorkClass{
+			regular: kvflowcontrol.Tokens(regularTokensPerStream.Get(&settings.SV)),
+			elastic: kvflowcontrol.Tokens(elasticTokensPerStream.Get(&settings.SV)),
+		}
+		adjustment := tokensPerWorkClass{
+			regular: now[regular] - before[regular],
+			elastic: now[elastic] - before[elastic],
+		}
+		c.mu.limit = now
+		for _, b := range c.mu.buckets {
+			b.tokens[regular] += adjustment[regular]
+			b.tokens[elastic] += adjustment[elastic]
+			c.metrics.onTokenAdjustment(adjustment)
+			if adjustment[regular] > 0 || adjustment[elastic] > 0 {
+				b.signal() // signal a waiter, if any
+			}
+		}
+	})
+	c.metrics = newMetrics(c)
+	registry.AddMetricStruct(c.metrics)
+	return c
+}
+
+// Admit is part of the kvflowcontrol.Controller interface. It blocks until
+// there are flow tokens available for replication over the given stream for
+// work of the given priority.
+func (c *Controller) Admit(
+	ctx context.Context, pri admissionpb.WorkPriority, _ time.Time, stream kvflowcontrol.Stream,
+) error {
+	class := admissionpb.WorkClassFromPri(pri)
+	c.metrics.onWaiting(class)
+
+	logged := false
+	tstart := c.clock.PhysicalTime()
+	for {
+		c.mu.Lock()
+		b := c.getBucketLocked(stream)
+		tokens := b.tokens[class]
+		c.mu.Unlock()
+
+		if tokens > 0 {
+			if log.ExpensiveLogEnabled(ctx, 2) {
+				log.Infof(ctx, "flow tokens available (pri=%s stream=%s tokens=%s wait-duration=%s)",
+					pri, stream, tokens, c.clock.PhysicalTime().Sub(tstart))
+			}
+
+			// TODO(irfansharif): Right now we continue forwarding admission
+			// grants to request while the available tokens > 0, which can lead
+			// to over-admission since deduction is deferred (see
+			// testdata/simulation/over_admission).
+			// A. One mitigation could be terminating grant forwarding if the
+			//    'tentatively deducted tokens' exceeds some amount (say, 16
+			//    MiB). When tokens are actually deducted, we'll reduce from
+			//    this 'tentatively deducted' count. We can re-signal() on every
+			//    actual token deduction where available tokens is still > 0.
+			// B. The pathological case with A is when all these tentatively
+			//    deducted tokens are due to requests that are waiting on
+			//    latches and locks. And the next request that wants to be
+			//    admitted is not contending with those latches/locks but gets
+			//    stuck behind it anyway. We could instead count the # of
+			//    requests that go through this bucket and are also past the
+			//    latch/lock acquisition but not yet evaluated, and block if
+			//    that count is greater than some small multiple of GOMAXPROCS.
+
+			b.signal() // signal a waiter, if any
+			c.metrics.onAdmitted(class, c.clock.PhysicalTime().Sub(tstart))
+			return nil
+		}
+
+		if !logged && log.ExpensiveLogEnabled(ctx, 2) {
+			log.Infof(ctx, "waiting for flow tokens (pri=%s stream=%s tokens=%s)",
+				pri, stream, tokens)
+			logged = true
+		}
+
+		select {
+		case <-b.wait(): // wait for a signal
+		case <-ctx.Done():
+			if ctx.Err() != nil {
+				c.metrics.onErrored(class)
+			}
+			return ctx.Err()
+		}
+	}
+
+	// TODO(irfansharif): Use the create time for ordering among waiting
+	// requests. Integrate it with epoch-LIFO.
+}
+
+// DeductTokens is part of the kvflowcontrol.Controller interface.
+func (c *Controller) DeductTokens(
+	ctx context.Context,
+	pri admissionpb.WorkPriority,
+	tokens kvflowcontrol.Tokens,
+	stream kvflowcontrol.Stream,
+) bool {
+	if tokens < 0 {
+		log.Fatalf(ctx, "malformed argument: -ve tokens deducted (pri=%s tokens=%s stream=%s)",
+			pri, tokens, stream)
+	}
+	c.adjustTokens(ctx, pri, -tokens, stream)
+	return true
+}
+
+// ReturnTokens is part of the kvflowcontrol.Controller interface.
+func (c *Controller) ReturnTokens(
+	ctx context.Context,
+	pri admissionpb.WorkPriority,
+	tokens kvflowcontrol.Tokens,
+	stream kvflowcontrol.Stream,
+) {
+	if tokens < 0 {
+		log.Fatalf(ctx, "malformed argument: -ve tokens deducted (pri=%s tokens=%s stream=%s)",
+			pri, tokens, stream)
+	}
+	c.adjustTokens(ctx, pri, tokens, stream)
+}
+
+func (c *Controller) adjustTokens(
+	ctx context.Context,
+	pri admissionpb.WorkPriority,
+	delta kvflowcontrol.Tokens,
+	stream kvflowcontrol.Stream,
+) {
+	class := admissionpb.WorkClassFromPri(pri)
+
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	b := c.getBucketLocked(stream)
+	adjustment, unaccounted := b.adjust(ctx, class, delta, c.mu.limit)
+	c.metrics.onTokenAdjustment(adjustment)
+	c.metrics.onUnaccounted(unaccounted)
+	if adjustment[regular] > 0 || adjustment[elastic] > 0 {
+		b.signal() // signal a waiter, if any
+	}
+
+	if log.ExpensiveLogEnabled(ctx, 2) {
+		log.Infof(ctx, "adjusted flow tokens (pri=%s stream=%s delta=%s): regular=%s elastic=%s",
+			pri, stream, delta, b.tokens[regular], b.tokens[elastic])
+	}
+}
+
+func (c *Controller) getBucketLocked(stream kvflowcontrol.Stream) bucket {
+	b, ok := c.mu.buckets[stream]
+	if !ok {
+		b = newBucket(c.mu.limit)
+		c.mu.buckets[stream] = b
+	}
+	return b
+}
+
+// bucket holds flow tokens for {regular,elastic} traffic over a
+// kvflowcontrol.Stream. It's used to synchronize handoff between threads
+// returning and waiting for flow tokens.
+type bucket struct {
+	tokens tokensPerWorkClass // protected by Controller.mu
+	// Waiting requests do so by waiting on signalCh without holding mutexes.
+	// Requests first check for available tokens, waiting if unavailable.
+	// - Whenever tokens are returned, signalCh is signaled, waking up a single
+	//   waiting request. If the request finds no available tokens, it starts
+	//   waiting again.
+	// - Whenever a request gets admitted, it signals the next waiter if any.
+	// The invariant we are ensuring is that whenever there are tokens
+	// available, the channel will have an entry, so at least one request that
+	// observed unavailable tokens will get unblocked, which will in turn
+	// unblock others. The concurrent request that adds tokens also tops up the
+	// channel so that the at least one waiter that observed unavailable tokens
+	// will find the channel signaled.
+	signalCh chan struct{}
+}
+
+func newBucket(t tokensPerWorkClass) bucket {
+	return bucket{
+		tokens: map[admissionpb.WorkClass]kvflowcontrol.Tokens{
+			regular: t[regular],
+			elastic: t[elastic],
+		},
+		signalCh: make(chan struct{}, 1),
+	}
+}
+
+func (b *bucket) signal() {
+	select {
+	case b.signalCh <- struct{}{}: // non-blocking channel write that ensures it's topped up to 1 entry
+	default:
+	}
+}
+
+func (b *bucket) wait() chan struct{} {
+	return b.signalCh
+}
+
+func (b *bucket) adjust(
+	ctx context.Context,
+	class admissionpb.WorkClass,
+	delta kvflowcontrol.Tokens,
+	limit tokensPerWorkClass,
+) (adjustment, unaccounted tokensPerWorkClass) {
+	unaccounted = tokensPerWorkClass{
+		regular: 0,
+		elastic: 0,
+	}
+
+	before := tokensPerWorkClass{
+		regular: b.tokens[regular],
+		elastic: b.tokens[elastic],
+	}
+
+	switch class {
+	case elastic:
+		// Elastic {deductions,returns} only affect elastic flow tokens.
+		b.tokens[class] += delta
+		if delta > 0 && b.tokens[class] > limit[class] {
+			unaccounted[class] = b.tokens[class] - limit[class]
+			b.tokens[class] = limit[class] // enforce ceiling
+		}
+	case regular:
+		b.tokens[class] += delta
+		if delta > 0 && b.tokens[class] > limit[class] {
+			unaccounted[class] = b.tokens[class] - limit[class]
+			b.tokens[class] = limit[class] // enforce ceiling
+		}
+
+		b.tokens[elastic] += delta
+		if delta > 0 && b.tokens[elastic] > limit[elastic] {
+			unaccounted[elastic] = b.tokens[elastic] - limit[elastic]
+			b.tokens[elastic] = limit[elastic] // enforce ceiling
+		}
+	}
+
+	if buildutil.CrdbTestBuild && (unaccounted[regular] != 0 || unaccounted[elastic] != 0) {
+		log.Fatalf(ctx, "unaccounted[regular]=%s unaccounted[elastic]=%s for class=%s delta=%s limit[regular]=%s limit[elastic]=%s",
+			unaccounted[regular], unaccounted[elastic], class, delta, limit[regular], limit[elastic])
+	}
+
+	adjustment = tokensPerWorkClass{
+		regular: b.tokens[regular] - before[regular],
+		elastic: b.tokens[elastic] - before[elastic],
+	}
+	return adjustment, unaccounted
+}
+
+type tokensPerWorkClass map[admissionpb.WorkClass]kvflowcontrol.Tokens
+
+const (
+	minTokensPerStream kvflowcontrol.Tokens = 1 << 20  // 1 MiB
+	maxTokensPerStream kvflowcontrol.Tokens = 64 << 20 // 64 MiB
+)
+
+func validateTokenRange(b int64) error {
+	t := kvflowcontrol.Tokens(b)
+	if t < minTokensPerStream {
+		return fmt.Errorf("minimum flowed tokens allowed is %s, got %s", minTokensPerStream, t)
+	}
+	if t > maxTokensPerStream {
+		return fmt.Errorf("maximum flow tokens allowed is %s, got %s", maxTokensPerStream, t)
+	}
+	return nil
+}
+
+func (c *Controller) testingGetTokensForStream(stream kvflowcontrol.Stream) tokensPerWorkClass {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	ret := make(map[admissionpb.WorkClass]kvflowcontrol.Tokens)
+	for wc, c := range c.getBucketLocked(stream).tokens {
+		ret[wc] = c
+	}
+	return ret
+}
+
+func (c *Controller) testingGetLimit() tokensPerWorkClass {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.mu.limit
+}
+
+// testingNonBlockingAdmit is a non-blocking alternative to Admit() for use in
+// tests.
+// - it checks if we have a non-zero number of flow tokens
+// - if we do, we return immediately with admitted=true
+// - if we don't, we return admitted=false and two callbacks:
+//   - signaled, which can be polled to check whether we're ready to try and
+//     admitting again;
+//   - admit, which can be used to try and admit again. If still not admitted,
+//     callers are to wait until they're signaled again.
+func (c *Controller) testingNonBlockingAdmit(
+	pri admissionpb.WorkPriority, stream kvflowcontrol.Stream,
+) (admitted bool, signaled func() bool, admit func() bool) {
+	class := admissionpb.WorkClassFromPri(pri)
+	c.metrics.onWaiting(class)
+
+	tstart := c.clock.PhysicalTime()
+	admit = func() bool {
+		c.mu.Lock()
+		b := c.getBucketLocked(stream)
+		tokens := b.tokens[class]
+		c.mu.Unlock()
+
+		if tokens <= 0 {
+			return false
+		}
+
+		b.signal() // signal a waiter, if any
+		c.metrics.onAdmitted(class, c.clock.PhysicalTime().Sub(tstart))
+		return true
+	}
+
+	if admit() {
+		return true, nil, nil
+	}
+
+	b := c.testingGetBucket(stream)
+	return false, b.testingSignaled, admit
+}
+
+func (c *Controller) testingGetBucket(stream kvflowcontrol.Stream) bucket {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+	return c.getBucketLocked(stream)
+}
+
+func (b *bucket) testingSignaled() bool {
+	select {
+	case <-b.wait(): // check if signaled
+		return true
+	default:
+		return false
+	}
+}
diff --git a/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/kvflowcontroller_metrics.go b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/kvflowcontroller_metrics.go
new file mode 100644
index 000000000000..9a1eb4f1c40f
--- /dev/null
+++ b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/kvflowcontroller_metrics.go
@@ -0,0 +1,238 @@
+// Copyright 2023 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package kvflowcontroller
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/cockroachdb/cockroach/pkg/base"
+	"github.com/cockroachdb/cockroach/pkg/util/admission/admissionpb"
+	"github.com/cockroachdb/cockroach/pkg/util/metric"
+)
+
+var (
+	// Metric templates for the flow token controller. We make use of aggmetrics
+	// to get per-tenant metrics and an aggregation across all tenants. Within a
+	// tenant, we maintain flow tokens for each admissionpb.WorkClass with
+	// appropriately segmented metrics. We don't export metrics at a per
+	// kvflowcontrol.Stream-level; streams are identified (partly) by the store
+	// ID receiving replication traffic, which is a high cardinality measure
+	// (storeIDs could ratchet up arbitrarily). The similar argument technically
+	// applies for per-tenant metrics, but there we'd rather eat the cost.
+	//
+	// TODO(irfansharif): Actually use aggmetrics.
+	// TODO(irfansharif): Consider aggregated metrics per remote store,
+	// aggregated across all tenants.
+	// TODO(irfansharif): To improve upon the tenant*stores cardinality,
+	// consider "inspectz" style pages to give token counts and queue lengths of
+	// individual buckets (#66772).
+
+	flowTokensAvailable = metric.Metadata{
+		Name:        "kvadmission.flow_controller.%s_tokens_available",
+		Help:        "Flow tokens available for %s requests, across all replication streams",
+		Measurement: "Bytes",
+		Unit:        metric.Unit_BYTES,
+	}
+
+	flowTokensDeducted = metric.Metadata{
+		Name:        "kvadmission.flow_controller.%s_tokens_deducted",
+		Help:        "Flow tokens deducted by %s requests, across all replication streams",
+		Measurement: "Bytes",
+		Unit:        metric.Unit_BYTES,
+	}
+
+	flowTokensReturned = metric.Metadata{
+		Name:        "kvadmission.flow_controller.%s_tokens_returned",
+		Help:        "Flow tokens returned by %s requests, across all replication streams",
+		Measurement: "Bytes",
+		Unit:        metric.Unit_BYTES,
+	}
+
+	flowTokensUnaccounted = metric.Metadata{
+		Name:        "kvadmission.flow_controller.%s_tokens_unaccounted",
+		Help:        "Flow tokens returned by %s requests that were unaccounted for, across all replication streams",
+		Measurement: "Bytes",
+		Unit:        metric.Unit_BYTES,
+	}
+
+	requestsWaiting = metric.Metadata{
+		Name:        "kvadmission.flow_controller.%s_requests_waiting",
+		Help:        "Number of %s requests waiting for flow tokens",
+		Measurement: "Requests",
+		Unit:        metric.Unit_COUNT,
+	}
+
+	requestsAdmitted = metric.Metadata{
+		Name:        "kvadmission.flow_controller.%s_requests_admitted",
+		Help:        "Number of %s requests admitted by the flow controller",
+		Measurement: "Requests",
+		Unit:        metric.Unit_COUNT,
+	}
+
+	requestsErrored = metric.Metadata{
+		Name:        "kvadmission.flow_controller.%s_requests_errored",
+		Help:        "Number of %s requests that errored out while waiting for flow tokens",
+		Measurement: "Requests",
+		Unit:        metric.Unit_COUNT,
+	}
+
+	waitDuration = metric.Metadata{
+		Name:        "kvadmission.flow_controller.%s_wait_duration",
+		Help:        "Latency histogram for time %s requests spent waiting for flow tokens",
+		Measurement: "Nanoseconds",
+		Unit:        metric.Unit_NANOSECONDS,
+	}
+
+	totalStreamCount = metric.Metadata{
+		Name:        "kvadmission.flow_controller.%s_stream_count",
+		Help:        "Total number of replication streams for %s requests",
+		Measurement: "Count",
+		Unit:        metric.Unit_COUNT,
+	}
+
+	blockedStreamCount = metric.Metadata{
+		Name:        "kvadmission.flow_controller.%s_blocked_stream_count",
+		Help:        "Number of replication streams with no flow tokens available for %s requests",
+		Measurement: "Count",
+		Unit:        metric.Unit_COUNT,
+	}
+)
+
+// annotateMetricTemplateWithWorkClass uses the given metric template to build
+// one suitable for the specific work class.
+func annotateMetricTemplateWithWorkClass(
+	wc admissionpb.WorkClass, tmpl metric.Metadata,
+) metric.Metadata {
+	rv := tmpl
+	rv.Name = fmt.Sprintf(tmpl.Name, wc)
+	rv.Help = fmt.Sprintf(tmpl.Help, wc)
+	return rv
+}
+
+type metrics struct {
+	FlowTokensAvailable   [admissionpb.NumWorkClasses]*metric.Gauge
+	FlowTokensDeducted    [admissionpb.NumWorkClasses]*metric.Counter
+	FlowTokensReturned    [admissionpb.NumWorkClasses]*metric.Counter
+	FlowTokensUnaccounted [admissionpb.NumWorkClasses]*metric.Counter
+	RequestsWaiting       [admissionpb.NumWorkClasses]*metric.Gauge
+	RequestsAdmitted      [admissionpb.NumWorkClasses]*metric.Counter
+	RequestsErrored       [admissionpb.NumWorkClasses]*metric.Counter
+	WaitDuration          [admissionpb.NumWorkClasses]metric.IHistogram
+	TotalStreamCount      [admissionpb.NumWorkClasses]*metric.Gauge
+	BlockedStreamCount    [admissionpb.NumWorkClasses]*metric.Gauge
+}
+
+var _ metric.Struct = &metrics{}
+
+func newMetrics(c *Controller) *metrics {
+	m := &metrics{}
+	for _, wc := range []admissionpb.WorkClass{
+		admissionpb.RegularWorkClass,
+		admissionpb.ElasticWorkClass,
+	} {
+		wc := wc // copy loop variable
+		m.FlowTokensAvailable[wc] = metric.NewFunctionalGauge(
+			annotateMetricTemplateWithWorkClass(wc, flowTokensAvailable),
+			func() int64 {
+				sum := int64(0)
+				c.mu.Lock()
+				defer c.mu.Unlock()
+				for _, wbc := range c.mu.buckets {
+					sum += int64(wbc.tokens[wc])
+				}
+				return sum
+			},
+		)
+		m.FlowTokensDeducted[wc] = metric.NewCounter(
+			annotateMetricTemplateWithWorkClass(wc, flowTokensDeducted),
+		)
+		m.FlowTokensReturned[wc] = metric.NewCounter(
+			annotateMetricTemplateWithWorkClass(wc, flowTokensReturned),
+		)
+		m.FlowTokensUnaccounted[wc] = metric.NewCounter(
+			annotateMetricTemplateWithWorkClass(wc, flowTokensUnaccounted),
+		)
+		m.RequestsWaiting[wc] = metric.NewGauge(
+			annotateMetricTemplateWithWorkClass(wc, requestsWaiting),
+		)
+		m.RequestsAdmitted[wc] = metric.NewCounter(
+			annotateMetricTemplateWithWorkClass(wc, requestsAdmitted),
+		)
+		m.RequestsErrored[wc] = metric.NewCounter(
+			annotateMetricTemplateWithWorkClass(wc, requestsErrored),
+		)
+		m.WaitDuration[wc] = metric.NewHistogram(
+			metric.HistogramOptions{
+				Metadata: annotateMetricTemplateWithWorkClass(wc, waitDuration),
+				Duration: base.DefaultHistogramWindowInterval(),
+				Buckets:  metric.IOLatencyBuckets,
+				Mode:     metric.HistogramModePrometheus,
+			},
+		)
+		m.TotalStreamCount[wc] = metric.NewFunctionalGauge(
+			annotateMetricTemplateWithWorkClass(wc, totalStreamCount),
+			func() int64 {
+				c.mu.Lock()
+				defer c.mu.Unlock()
+				return int64(len(c.mu.buckets))
+			},
+		)
+		m.BlockedStreamCount[wc] = metric.NewFunctionalGauge(
+			annotateMetricTemplateWithWorkClass(wc, blockedStreamCount),
+			func() int64 {
+				count := int64(0)
+				c.mu.Lock()
+				defer c.mu.Unlock()
+				for _, wbc := range c.mu.buckets {
+					if wbc.tokens[wc] <= 0 {
+						count += 1
+					}
+				}
+				return count
+			},
+		)
+	}
+	return m
+}
+
+func (m *metrics) onWaiting(class admissionpb.WorkClass) {
+	m.RequestsWaiting[class].Inc(1)
+}
+
+func (m *metrics) onAdmitted(class admissionpb.WorkClass, dur time.Duration) {
+	m.RequestsAdmitted[class].Inc(1)
+	m.RequestsWaiting[class].Dec(1)
+	m.WaitDuration[class].RecordValue(dur.Nanoseconds())
+}
+
+func (m *metrics) onErrored(class admissionpb.WorkClass) {
+	m.RequestsErrored[class].Inc(1)
+}
+
+func (m *metrics) onTokenAdjustment(adjustment tokensPerWorkClass) {
+	for class, delta := range adjustment {
+		if delta < 0 {
+			m.FlowTokensDeducted[class].Inc(-int64(delta))
+		} else if delta > 0 {
+			m.FlowTokensReturned[class].Inc(int64(delta))
+		}
+	}
+}
+
+func (m *metrics) onUnaccounted(unaccounted tokensPerWorkClass) {
+	for class, delta := range unaccounted {
+		m.FlowTokensUnaccounted[class].Inc(int64(delta))
+	}
+}
+
+// MetricStruct implements the metric.Struct interface.
+func (m *metrics) MetricStruct() {}
diff --git a/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/kvflowcontroller_simulation_test.go b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/kvflowcontroller_simulation_test.go
new file mode 100644
index 000000000000..b595f06d645d
--- /dev/null
+++ b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/kvflowcontroller_simulation_test.go
@@ -0,0 +1,523 @@
+// Copyright 2023 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package kvflowcontroller
+
+import (
+	"context"
+	"fmt"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/cockroachdb/cockroach/pkg/kv/kvserver/kvflowcontrol"
+	"github.com/cockroachdb/cockroach/pkg/roachpb"
+	"github.com/cockroachdb/cockroach/pkg/settings/cluster"
+	"github.com/cockroachdb/cockroach/pkg/testutils/datapathutils"
+	"github.com/cockroachdb/cockroach/pkg/util/admission/admissionpb"
+	"github.com/cockroachdb/cockroach/pkg/util/asciitsdb"
+	"github.com/cockroachdb/cockroach/pkg/util/hlc"
+	"github.com/cockroachdb/cockroach/pkg/util/leaktest"
+	"github.com/cockroachdb/cockroach/pkg/util/log"
+	"github.com/cockroachdb/cockroach/pkg/util/metric"
+	"github.com/cockroachdb/cockroach/pkg/util/timeutil"
+	"github.com/cockroachdb/datadriven"
+	"github.com/dustin/go-humanize"
+	"github.com/guptarohit/asciigraph"
+	"github.com/mkungla/bexp/v3"
+	"github.com/stretchr/testify/require"
+)
+
+// TestUsingSimulation is a data-driven test for kvflowcontrol.Controller.
+// It gives package authors a way to understand how flow tokens are maintained
+// for individual replication streams, how write bandwidth is shaped by these
+// tokens, and how requests queue/dequeue internally. We provide the following
+// syntax:
+//
+//   - "init"
+//     Initialize the flow controller and test simulator.
+//
+//   - "timeline"
+//     start=<duration> end=<duration> class={regular,elastic} \
+//     stream=t<int>/s<int> adjust={+,-}<bytes>/s rate=<int>/s \
+//     [deduction-delay=<duration>]
+//     ....
+//     Creates a "thread" that operates between t='start' to (non-inclusive)
+//     t='end', issuing the specified 'rate' of requests of the given work
+//     'class', over the given 'stream', where the flow tokens are
+//     {deducted,returned} with the given bandwidth. The 'rate' controls the
+//     granularity of token adjustment, i.e. if adjust=+100bytes/s and
+//     rate=5/s, then each return adjusts by +100/5 = +20bytes. If flow tokens
+//     are being deducted (-ve 'adjust'), they go through Admit() followed by
+//     DeductTokens(). If they're being returned (+ve 'adjust'), they simply go
+//     through ReturnTokens(). The optional 'deduction-delay' parameter controls
+//     the number of ticks between each request being granted admission and it
+//     deducting the corresponding flow tokens.
+//
+//   - "simulate" [end=<duration>]
+//     Simulate timelines until the optionally specified timestamp. If no
+//     timestamp is specified, the largest end time of all registered timelines
+//     is used instead.
+//
+//   - "plot" [height=<int>] [width=<int>] [precision=<int>] \
+//     [start=<duration>] [end=<duration>]
+//     <metric selector> unit=<string> [rate=true]
+//     ....
+//     Plot the flow controller specified metrics (and optionally its rate of
+//     change) with the specified units. The following metrics are supported:
+//     a. kvadmission.flow_controller.{regular,elastic}_tokens_{available,deducted,returned}
+//     b. kvadmission.flow_controller.{regular,elastic}_requests_{waiting,admitted,errored}
+//     c. kvadmission.flow_controller.{regular,elastic}{,_blocked}_stream_count
+//     d. kvadmission.flow_controller.{regular,elastic}_wait_duration
+//     To overlay metrics onto the same plot, the selector supports curly brace
+//     expansion. If the unit is one of {MiB,MB,KB,KiB,s,ms,us,μs}, or the
+//     bandwidth equivalents (<byte size>/s), the y-axis is automatically
+//     converted.
+//
+// Internally we make use of a test-only non-blocking interface for the flow
+// controller in order to enable deterministic simulation.
+func TestUsingSimulation(t *testing.T) {
+	defer leaktest.AfterTest(t)()
+	defer log.Scope(t).Close(t)
+
+	datadriven.Walk(t, datapathutils.TestDataPath(t, "simulation"), func(t *testing.T, path string) {
+		var (
+			controller *Controller
+			simulator  *simulator
+			tsdb       *asciitsdb.TSDB
+			mtime      *timeutil.ManualTime
+		)
+
+		ctx := context.Background()
+		datadriven.RunTest(t, path,
+			func(t *testing.T, d *datadriven.TestData) string {
+				switch d.Cmd {
+				case "init":
+					registry := metric.NewRegistry()
+					tsdb = asciitsdb.New(t, registry)
+					mtime = timeutil.NewManualTime(tstart)
+					controller = New(
+						registry,
+						cluster.MakeTestingClusterSettings(),
+						hlc.NewClock(mtime, time.Nanosecond /* maxOffset */),
+					)
+					tsdb.Register(controller.metrics)
+					simulator = newSimulator(t, controller, tsdb, mtime)
+					return ""
+
+				case "timeline":
+					require.NotNilf(t, controller, "uninitialized flow controller (did you use 'init'?)")
+					require.NotNilf(t, simulator, "uninitialized simulator (did you use 'init'?)")
+
+					for _, line := range strings.Split(d.Input, "\n") {
+						parts := strings.Fields(line)
+						require.True(t, len(parts) >= 6, `expected form:
+	start=<duration> end=<duration> class={regular,elastic} \
+	stream=t<int>/s<int> adjust={+,-}<bytes>/s rate=<int>/s \
+	[deduction-delay=<duration>]
+`)
+
+						var (
+							start, end time.Time
+							pri        admissionpb.WorkPriority
+							stream     kvflowcontrol.Stream
+							delta      kvflowcontrol.Tokens
+							rate       int
+						)
+
+						for i := range parts {
+							parts[i] = strings.TrimSpace(parts[i])
+						}
+
+						require.True(t, strings.HasPrefix(parts[0], "start="))
+						require.True(t, strings.HasPrefix(parts[1], "end="))
+						require.True(t, strings.HasPrefix(parts[2], "class="))
+						require.True(t, strings.HasPrefix(parts[3], "stream="))
+						require.True(t, strings.HasPrefix(parts[4], "adjust="))
+						require.True(t, strings.HasPrefix(parts[5], "rate="))
+
+						for i := range parts[:6] {
+							inner := strings.Split(parts[i], "=")
+							require.Len(t, inner, 2)
+							parts[i] = strings.TrimSpace(inner[1])
+						}
+
+						// Parse start=<duration>.
+						dur, err := time.ParseDuration(parts[0])
+						require.NoError(t, err)
+						start = mtime.Now().Add(dur)
+
+						// Parse end=<duration>.
+						dur, err = time.ParseDuration(parts[1])
+						require.NoError(t, err)
+						end = mtime.Now().Add(dur)
+
+						// Parse class={regular,elastic}.
+						switch parts[2] {
+						case "regular":
+							pri = admissionpb.NormalPri
+						case "elastic":
+							pri = admissionpb.BulkNormalPri
+						default:
+							t.Fatalf("unexpected class: %s", parts[1])
+						}
+
+						{ // Parse stream=t<int>/s<int>.
+							inner := strings.Split(parts[3], "/")
+							require.Len(t, inner, 2)
+
+							ti, err := strconv.Atoi(strings.TrimPrefix(inner[0], "t"))
+							require.NoError(t, err)
+
+							si, err := strconv.Atoi(strings.TrimPrefix(inner[1], "s"))
+							require.NoError(t, err)
+
+							stream = kvflowcontrol.Stream{
+								TenantID: roachpb.MustMakeTenantID(uint64(ti)),
+								StoreID:  roachpb.StoreID(si),
+							}
+						}
+
+						// Parse adjust={+,-}<bytes>/s.
+						isPositive := strings.Contains(parts[4], "+")
+						parts[4] = strings.TrimPrefix(parts[4], "+")
+						parts[4] = strings.TrimPrefix(parts[4], "-")
+						bytes, err := humanize.ParseBytes(strings.TrimSuffix(parts[4], "/s"))
+						require.NoError(t, err)
+						delta = kvflowcontrol.Tokens(int64(bytes))
+						if !isPositive {
+							delta = -delta
+						}
+
+						// Parse rate=<int>/s.
+						rate, err = strconv.Atoi(strings.TrimSuffix(parts[5], "/s"))
+						require.NoError(t, err)
+
+						deductionDelay := 0
+						if len(parts) > 6 {
+							for _, part := range parts[6:] {
+								part = strings.TrimSpace(part)
+								if strings.HasPrefix(part, "deduction-delay=") {
+									part = strings.TrimPrefix(part, "deduction-delay=")
+									dur, err := time.ParseDuration(part)
+									require.NoError(t, err)
+									deductionDelay = int(dur.Nanoseconds() / tick.Nanoseconds())
+								}
+							}
+						}
+						simulator.timeline(start, end, pri, stream, delta, rate, deductionDelay)
+					}
+					return ""
+
+				case "simulate":
+					require.NotNilf(t, simulator, "uninitialized simulator (did you use 'init'?)")
+					var end time.Time
+					if d.HasArg("end") {
+						// Parse end=<duration>.
+						var endStr string
+						d.ScanArgs(t, "end", &endStr)
+						dur, err := time.ParseDuration(endStr)
+						require.NoError(t, err)
+						end = mtime.Now().Add(dur)
+					}
+					simulator.simulate(ctx, end)
+					return ""
+
+				case "plot":
+					var h, w, p = 15, 40, 1
+					if d.HasArg("height") {
+						d.ScanArgs(t, "height", &h)
+					}
+					if d.HasArg("width") {
+						d.ScanArgs(t, "width", &w)
+					}
+					if d.HasArg("precision") {
+						d.ScanArgs(t, "precision", &p)
+					}
+
+					var buf strings.Builder
+					for i, line := range strings.Split(d.Input, "\n") {
+						var (
+							selector, unit string
+							rated          bool
+						)
+						parts := strings.Fields(line)
+						for i, part := range parts {
+							part = strings.TrimSpace(part)
+							if i == 0 {
+								selector = part
+								continue
+							}
+
+							if strings.HasPrefix(part, "rate=") {
+								var err error
+								rated, err = strconv.ParseBool(strings.TrimPrefix(part, "rate="))
+								require.NoError(t, err)
+							}
+
+							if strings.HasPrefix(part, "unit=") {
+								unit = strings.TrimPrefix(part, "unit=")
+							}
+						}
+
+						caption := strings.TrimPrefix(selector, "kvadmission.flow_controller.")
+						if rated {
+							caption = fmt.Sprintf("rate(%s)", caption)
+						}
+						caption = fmt.Sprintf("%s (%s)", caption, unit)
+
+						options := []asciitsdb.Option{
+							asciitsdb.WithGraphOptions(
+								asciigraph.Height(h),
+								asciigraph.Width(w),
+								asciigraph.Precision(uint(p)),
+								asciigraph.Caption(caption),
+							),
+						}
+						if rated {
+							options = append(options, asciitsdb.WithRate(int(time.Second/metricTick)))
+						}
+						switch unit {
+						case "μs", "us", "microseconds":
+							time.Microsecond.Nanoseconds()
+							options = append(options, asciitsdb.WithDivisor(float64(time.Microsecond.Nanoseconds())) /* ns => μs conversion  */)
+						case "ms", "milliseconds":
+							options = append(options, asciitsdb.WithDivisor(float64(time.Millisecond.Nanoseconds())) /* ns => μs conversion  */)
+						case "s", "seconds":
+							options = append(options, asciitsdb.WithDivisor(float64(time.Second.Nanoseconds())) /* ns => μs conversion  */)
+						case "MiB", "MiB/s":
+							options = append(options, asciitsdb.WithDivisor(humanize.MiByte) /* 1 MiB */)
+						case "MB", "MB/s":
+							options = append(options, asciitsdb.WithDivisor(humanize.MByte) /* 1 MB */)
+						case "KiB", "KiB/s":
+							options = append(options, asciitsdb.WithDivisor(humanize.KiByte) /* 1 KiB */)
+						case "KB", "KB/s":
+							options = append(options, asciitsdb.WithDivisor(humanize.KByte) /* 1 KB */)
+						default:
+						}
+
+						start := tstart
+						if d.HasArg("start") {
+							// Parse start=<duration>.
+							var startStr string
+							d.ScanArgs(t, "start", &startStr)
+							dur, err := time.ParseDuration(startStr)
+							require.NoError(t, err)
+							start = tstart.Add(dur)
+							options = append(options, asciitsdb.WithOffset(start.Sub(tstart).Nanoseconds()/metricTick.Nanoseconds()))
+						}
+
+						if d.HasArg("end") {
+							// Parse end=<duration>.
+							var endStr string
+							d.ScanArgs(t, "end", &endStr)
+							dur, err := time.ParseDuration(endStr)
+							require.NoError(t, err)
+							end := tstart.Add(dur)
+							options = append(options, asciitsdb.WithLimit(end.Sub(start).Nanoseconds()/metricTick.Nanoseconds()))
+						}
+
+						if i > 0 {
+							buf.WriteString("\n\n\n")
+						}
+						metrics := bexp.Parse(strings.TrimSpace(selector))
+						buf.WriteString(tsdb.Plot(metrics, options...))
+					}
+					return buf.String()
+
+				default:
+					return fmt.Sprintf("unknown command: %s", d.Cmd)
+				}
+			},
+		)
+	})
+}
+
+var tstart = timeutil.Unix(0, 0)
+
+const tick = time.Millisecond
+const metricTick = 100 * tick
+
+type simulator struct {
+	t *testing.T
+
+	controller *Controller
+	ticker     []ticker
+	tsdb       *asciitsdb.TSDB
+	mtime      *timeutil.ManualTime
+}
+
+func newSimulator(
+	t *testing.T, controller *Controller, tsdb *asciitsdb.TSDB, mtime *timeutil.ManualTime,
+) *simulator {
+	return &simulator{
+		t:          t,
+		tsdb:       tsdb,
+		controller: controller,
+		mtime:      mtime,
+	}
+}
+
+func (s *simulator) timeline(
+	start, end time.Time,
+	pri admissionpb.WorkPriority,
+	stream kvflowcontrol.Stream,
+	delta kvflowcontrol.Tokens,
+	rate, deductionDelay int,
+) {
+	if rate == 0 {
+		return // nothing to do
+	}
+	s.ticker = append(s.ticker, ticker{
+		t:          s.t,
+		controller: s.controller,
+
+		start:  start,
+		end:    end,
+		pri:    pri,
+		stream: stream,
+
+		deductionDelay: deductionDelay,
+		deduct:         make(map[time.Time][]func()),
+		waitHandles:    make(map[time.Time]waitHandle),
+
+		// Using the parameters above, we figure out two things:
+		// - On which ticks do we adjust flow tokens?
+		// - How much by, each time?
+		//
+		// If the request rate we're simulating is:
+		// - 1000/sec, we adjust flow tokens every tick(=1ms).
+		// - 500/sec, we adjust flow tokens every 2 ticks (=2ms).
+		// - ....
+		//
+		// How much do we adjust by each time? Given we're making 'rate' requests
+		// per second, and have to deduct 'delta' tokens per second, each request
+		// just deducts delta/rate.
+		mod:   int(time.Second/tick) / rate,
+		delta: kvflowcontrol.Tokens(int(delta) / rate),
+	})
+}
+
+func (s *simulator) simulate(ctx context.Context, end time.Time) {
+	s.mtime.Backwards(s.mtime.Since(tstart)) // reset to tstart
+	s.tsdb.Clear()
+	for i := range s.ticker {
+		s.ticker[i].reset()
+		if s.ticker[i].end.After(end) {
+			end = s.ticker[i].end
+		}
+	}
+
+	for {
+		t := s.mtime.Now()
+		if t.After(end) || t.Equal(end) {
+			break
+		}
+		for i := range s.ticker {
+			s.ticker[i].tick(ctx, t)
+		}
+		if t.UnixNano()%metricTick.Nanoseconds() == 0 {
+			s.tsdb.Scrape(ctx)
+		}
+		s.mtime.Advance(tick)
+	}
+}
+
+type waitHandle struct {
+	ctx      context.Context
+	signaled func() bool
+	admit    func() bool
+}
+
+type ticker struct {
+	t          *testing.T
+	start, end time.Time
+	pri        admissionpb.WorkPriority
+	stream     kvflowcontrol.Stream
+	delta      kvflowcontrol.Tokens
+	controller *Controller
+	mod, ticks int // used to control the ticks at which we interact with the controller
+
+	deduct      map[time.Time][]func()
+	waitHandles map[time.Time]waitHandle
+
+	deductionDelay int
+}
+
+func (ti *ticker) tick(ctx context.Context, t time.Time) {
+	if ds, ok := ti.deduct[t]; ok {
+		for _, deduct := range ds {
+			deduct()
+		}
+		delete(ti.deduct, t)
+	}
+	for key, handle := range ti.waitHandles {
+		// Process all waiting requests from earlier. Do this even if t >
+		// ti.end since these requests could've been generated earlier.
+		if handle.ctx.Err() != nil {
+			delete(ti.waitHandles, key)
+			continue
+		}
+		if !handle.signaled() {
+			continue
+		}
+		if handle.admit() {
+			if ti.deductionDelay == 0 {
+				ti.controller.adjustTokens(ctx, ti.pri, ti.delta, ti.stream)
+			} else {
+				future := t.Add(tick * time.Duration(ti.deductionDelay))
+				ti.deduct[future] = append(ti.deduct[future], func() {
+					ti.controller.adjustTokens(ctx, ti.pri, ti.delta, ti.stream)
+				})
+			}
+			delete(ti.waitHandles, key)
+			return
+		}
+	}
+
+	if t.Before(ti.start) || (t.After(ti.end) || t.Equal(ti.end)) {
+		return // we're outside our [ti.start, ti.end), there's nothing left to do
+	}
+
+	defer func() { ti.ticks += 1 }()
+	if ti.ticks%ti.mod != 0 {
+		return // nothing to do in this tick
+	}
+
+	if ti.delta >= 0 { // return tokens
+		ti.controller.adjustTokens(ctx, ti.pri, ti.delta, ti.stream)
+		return
+	}
+
+	admitted, signaled, admit := ti.controller.testingNonBlockingAdmit(ti.pri, ti.stream)
+	if admitted {
+		if ti.deductionDelay == 0 {
+			ti.controller.adjustTokens(ctx, ti.pri, ti.delta, ti.stream)
+		} else {
+			future := t.Add(tick * time.Duration(ti.deductionDelay))
+			ti.deduct[future] = append(ti.deduct[future], func() {
+				ti.controller.adjustTokens(ctx, ti.pri, ti.delta, ti.stream)
+			})
+		}
+		return
+	}
+	ti.waitHandles[t] = waitHandle{
+		ctx:      ctx,
+		signaled: signaled,
+		admit:    admit,
+	}
+}
+
+func (ti *ticker) reset() {
+	ti.ticks = 0
+	ti.deduct = make(map[time.Time][]func())
+	ti.waitHandles = make(map[time.Time]waitHandle)
+}
diff --git a/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/testdata/flow_token_adjustment b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/testdata/flow_token_adjustment
new file mode 100644
index 000000000000..5e4c3a460894
--- /dev/null
+++ b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/testdata/flow_token_adjustment
@@ -0,0 +1,65 @@
+init
+----
+
+adjust
+class=regular delta=-1MiB
+class=regular delta=-7MiB
+class=regular delta=-2MiB
+class=regular delta=-2MiB
+class=regular delta=+2MiB
+class=regular delta=-2MiB
+class=regular delta=+4MiB
+class=regular delta=+2MiB
+class=elastic delta=-2MiB
+class=regular delta=-2MiB
+class=regular delta=+2MiB
+class=elastic delta=+2MiB
+class=regular delta=+6MiB
+----
+
+history
+----
+                   regular |  elastic
+                    +16MiB |  +8.0MiB
+======================================
+ -1.0MiB regular    +15MiB |  +7.0MiB
+ -7.0MiB regular   +8.0MiB |      +0B (elastic blocked)
+ -2.0MiB regular   +6.0MiB |  -2.0MiB (elastic blocked)
+ -2.0MiB regular   +4.0MiB |  -4.0MiB (elastic blocked)
+ +2.0MiB regular   +6.0MiB |  -2.0MiB (elastic blocked)
+ -2.0MiB regular   +4.0MiB |  -4.0MiB (elastic blocked)
+ +4.0MiB regular   +8.0MiB |      +0B (elastic blocked)
+ +2.0MiB regular    +10MiB |  +2.0MiB
+ -2.0MiB elastic    +10MiB |      +0B (elastic blocked)
+ -2.0MiB regular   +8.0MiB |  -2.0MiB (elastic blocked)
+ +2.0MiB regular    +10MiB |      +0B (elastic blocked)
+ +2.0MiB elastic    +10MiB |  +2.0MiB
+ +6.0MiB regular    +16MiB |  +8.0MiB
+
+# ------------------------------------------------------
+
+init
+----
+
+adjust
+class=elastic delta=-7MiB
+class=regular delta=-7MiB
+class=elastic delta=+6MiB
+class=regular delta=-1MiB
+class=regular delta=-6MiB
+class=regular delta=+6MiB
+class=regular delta=-9MiB
+----
+
+history
+----
+                   regular |  elastic
+                    +16MiB |  +8.0MiB
+======================================
+ -7.0MiB elastic    +16MiB |  +1.0MiB
+ -7.0MiB regular   +9.0MiB |  -6.0MiB (elastic blocked)
+ +6.0MiB elastic   +9.0MiB |      +0B (elastic blocked)
+ -1.0MiB regular   +8.0MiB |  -1.0MiB (elastic blocked)
+ -6.0MiB regular   +2.0MiB |  -7.0MiB (elastic blocked)
+ +6.0MiB regular   +8.0MiB |  -1.0MiB (elastic blocked)
+ -9.0MiB regular   -1.0MiB |   -10MiB (regular and elastic blocked)
diff --git a/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/testdata/simulation/admitting_waiting_choppy b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/testdata/simulation/admitting_waiting_choppy
new file mode 100644
index 000000000000..371f31f87dc3
--- /dev/null
+++ b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/testdata/simulation/admitting_waiting_choppy
@@ -0,0 +1,198 @@
+# Show how waiting work ends up getting admitted choppily if the flow tokens
+# being returned are being done so in a similarly choppy way. This is showing
+# that we're shaping incoming writes to exactly the rate of flow token returns,
+# i.e. we're controlling the flow tightly.
+init
+----
+
+# Set up an open-loop thread issuing 2MiB/s of regular writes from t=0s to
+# t=25s.
+timeline
+start=0s  end=25s class=regular stream=t1/s1 adjust=-2MiB/s   rate=10/s
+----
+
+# Set up choppy flow token returns starting at t=15s. The average rate of
+# returns is lower than 2MiB/s, so we should always have some waiting work.
+timeline
+start=15s end=16s class=regular stream=t1/s1 adjust=+0.9MiB/s rate=10/s
+start=16s end=17s class=regular stream=t1/s1 adjust=+2.1MiB/s rate=10/s
+start=17s end=18s class=regular stream=t1/s1 adjust=+0.1MiB/s rate=10/s
+start=18s end=19s class=regular stream=t1/s1 adjust=+0.9MiB/s rate=10/s
+start=19s end=20s class=regular stream=t1/s1 adjust=+2.1MiB/s rate=10/s
+start=20s end=21s class=regular stream=t1/s1 adjust=+0.1MiB/s rate=10/s
+start=21s end=22s class=regular stream=t1/s1 adjust=+0.9MiB/s rate=10/s
+start=22s end=23s class=regular stream=t1/s1 adjust=+2.1MiB/s rate=10/s
+start=23s end=24s class=regular stream=t1/s1 adjust=+0.1MiB/s rate=10/s
+start=24s end=25s class=regular stream=t1/s1 adjust=+0.9MiB/s rate=10/s
+----
+
+simulate
+----
+
+# Observe the initial smooth rate of flow token deductions, and later the
+# choppier rate of flow token returns which we induced above. Notice that the
+# rate of flow token deductions exactly mirrors the flow token returns, so
+# traffic shaping is happening.
+plot
+kvadmission.flow_controller.regular_tokens_{deducted,returned}  unit=MiB/s rate=true
+kvadmission.flow_controller.regular_tokens_{deducted,returned}  unit=MiB
+kvadmission.flow_controller.regular_tokens_available            unit=MiB
+----
+----
+ 2.0 ┤ ╭──────────╮                 ╭╮   ╭╮
+ 1.9 ┤ │          │                 ││   ╭╮
+ 1.7 ┤ │          │            ╭╮╮  ││   ││
+ 1.6 ┤ │          │            │││  ││   ││
+ 1.5 ┤ │          ╰╮           │╰╮  ││  ╭╯│
+ 1.3 ┤ │           │           │ │  ││  │╯│
+ 1.2 ┤ │           │           │ │ ╭╯│╮ │ │
+ 1.1 ┤ │           │           │ │ │ ╰╮ │ │
+ 0.9 ┤ │           │          ╭╯ │ │  │ │ │╮╭
+ 0.8 ┤ │           │          │╯ │ │  │╭╯ │││
+ 0.7 ┤ │           │          │  │ │  ││  ╰╮│
+ 0.5 ┤ │           │          │  │╭╯  ││   ││
+ 0.4 ┤ │           │         ╭╯  ││╯  ││   ╰╯
+ 0.3 ┤ │           │         │╯  ││   ╰╯   ╰╯
+ 0.1 ┤ │           ╰╮        │   ╰╯   ╰╯
+ 0.0 ┼───────────────────────╯
+      rate(regular_tokens_{deducted,returned}) (MiB/s)
+
+
+ 26.2 ┤                                    ╭──
+ 24.5 ┤                                  ╭─╯
+ 22.7 ┤                               ╭──╯
+ 21.0 ┤                             ╭─╯
+ 19.2 ┤                          ╭──╯
+ 17.5 ┤                        ╭─╯
+ 15.7 ┤           ╭────────────╯
+ 14.0 ┤          ╭╯
+ 12.2 ┤        ╭─╯
+ 10.5 ┤       ╭╯                            ╭─
+  8.7 ┤     ╭─╯                          ╭──╯
+  7.0 ┤    ╭╯                         ╭──╯
+  5.2 ┤   ╭╯                        ╭─╯
+  3.5 ┤ ╭─╯                      ╭──╯
+  1.7 ┤╭╯                      ╭─╯
+  0.0 ┼────────────────────────╯
+       regular_tokens_{deducted,returned} (MiB)
+
+
+ 15.8 ┼╮
+ 14.7 ┤╰╮
+ 13.7 ┤ │
+ 12.6 ┤ ╰╮
+ 11.5 ┤  ╰╮
+ 10.5 ┤   ╰╮
+  9.4 ┤    ╰╮
+  8.3 ┤     ╰╮
+  7.3 ┤      │
+  6.2 ┤      ╰╮
+  5.1 ┤       ╰╮
+  4.1 ┤        ╰╮
+  3.0 ┤         ╰╮
+  1.9 ┤          ╰╮
+  0.9 ┤           │
+ -0.2 ┤           ╰───────────────────────────
+            regular_tokens_available (MiB)
+----
+----
+
+
+# Zoom into the more interesting second half of the graph, where flow tokens
+# are being returned choppily. Given the average rate of returns is lower
+# than what's being requested (2MiB/s), the total flow tokens available bounces
+# off of zero.
+plot start=15s end=30s
+kvadmission.flow_controller.regular_tokens_available            unit=MiB
+----
+  0.2 ┤                              ╭╮
+  0.2 ┤      ╭╮                     ╭╯│
+  0.1 ┤     ╭╯│                    ╭╯ │
+  0.1 ┤    ╭╯ │                   ╭╯  │
+  0.1 ┤   ╭╯  │       ╭╮ ╭╮       │   │
+  0.1 ┤   │   │       ││╭╯│       │   │
+  0.0 ┤   │   │    ╭╮ │╰╯ │       │   │
+  0.0 ┤   │   │   ╭╯│ │   │     ╭╮│   │   ╭╮
+ -0.0 ┤╭╮ │   │   │ │ │   │  ╭──╯││   │   ││ ╭
+ -0.0 ┤││╭╯   │   │ ╰╮│   │ ╭╯   ││   │   ││╭╯
+ -0.1 ┤│╰╯    │   │  ││   │╭╯    ╰╯   │   │╰╯
+ -0.1 ┤│      │   │  ╰╯   ╰╯          │   │
+ -0.1 ┼╯      │  ╭╯                   │  ╭╯
+ -0.1 ┤       │ ╭╯                    │ ╭╯
+ -0.2 ┤       │╭╯                     │╭╯
+ -0.2 ┤       ╰╯                      ╰╯
+            regular_tokens_available (MiB)
+
+
+# Note again the mirroring between token returns which immediately allows
+# admission, followed by token deductions.
+plot start=15s end=30s
+kvadmission.flow_controller.regular_tokens_{deducted,returned}  unit=MiB rate=true
+----
+ 2.1 ┤       ╭╮
+ 2.0 ┤      ╭╮│         ╭╮          ╭╮╮
+ 1.9 ┤      │╰╮         ││╮         │││
+ 1.7 ┤     ╭╯╯│        ╭╯╰╮        ╭╯╰╮
+ 1.6 ┤     ││ │╮       │╯ │        │╯ │
+ 1.4 ┤     │╯ ││      ╭╯  │       ╭╯  │╮
+ 1.3 ┤    ╭╯  ╰╮      │   ╰╮      │╯  ││
+ 1.1 ┤    │╯   │╮    ╭╯    │     ╭╯   ╰╮
+ 1.0 ┤   ╭╯    ││    │╯    │     │╯    │╮
+ 0.9 ┤   │╯    ╰╮   ╭╯     │╮   ╭╯     ││   ╭
+ 0.7 ┤  ╭╯      │   │      ╰╮  ╭╯      ││  ╭╯
+ 0.6 ┤ ╭╯╯      │╮ ╭╯       │  │╯      ╰╮  │╯
+ 0.4 ┤ │╯       ││╭╯        │ ╭╯        │╮╭╯
+ 0.3 ┤╭╯        ╰─╯│        ╰─╯         │╭╯
+ 0.1 ┼╯╯         │╭╯         ╰╯         ╰╯╯
+-0.0 ┼╯          ╰╯
+      rate(regular_tokens_{deducted,returned}) (MiB)
+
+
+# So we're still admitting work choppily, and observe corresponding deductions
+# in the waiting request rate. But given the open-loop thread above, the # of
+# waiting request is still growing unboundedly.
+plot start=15s end=30s
+kvadmission.flow_controller.regular_requests_{admitted,waiting} unit=reqs/s rate=true
+kvadmission.flow_controller.regular_requests_waiting unit=reqs
+----
+----
+ 10.7 ┤       ╭╮
+  9.9 ┼╮      ││  ╭╮                  ╭╮  ╭╮
+  9.2 ┤╰╮    ╭╯│  │╰╮    ╭─╮  ╭╮     ╭╯│  ││
+  8.4 ┤ │    │ ╰╮ │ │   ╭╯ │ ╭╯╰╮   ╭╯ │  │╰╮
+  7.7 ┤ │   ╭╯  │ │ ╰╮  │  │ │  │   │  ╰╮╭╯ │
+  6.9 ┤ ╰╮  │   │╭╯  │ ╭╯  ╰╮│  ╰╮ ╭╯   ││  ╰╮
+  6.1 ┤  ╰╮╭╯   ││   ╰╮│    ╭╯   │ │    ││   ╰
+  5.4 ┤   ││    ╰│    │╯    │    ╰╮╯    ╭╯
+  4.6 ┤   ╰╮    ╭╯    ╰╮    │    ╭╰╮    │╮
+  3.9 ┤   ╭╰╮   ││   ╭╯│    │╮   │ │    ││   ╭
+  3.1 ┤  ╭╯ ╰╮  │╰╮  │ ╰╮  ╭╯│  ╭╯ ╰╮  ╭╯│  ╭╯
+  2.3 ┤ ╭╯   │  │ │ ╭╯  ╰╮ │ │ ╭╯   ╰╮ │ ╰╮╭╯
+  1.6 ┤ │    ╰╮╭╯ │ │    │ │ ╰╮│     │ │  ││
+  0.8 ┤╭╯     ││  │╭╯    ╰─╯  ╰╯     ╰╮│  ╰╯
+  0.1 ┼╯      ││  ╰╯                  ╰╯
+ -0.7 ┤       ╰╯
+       rate(regular_requests_{admitted,waiting}) (reqs/s)
+
+
+ 118 ┤                                      ╭
+ 115 ┤                                   ╭──╯
+ 112 ┤                                  ╭╯
+ 108 ┤                                 ╭╯
+ 105 ┤                           ╭─────╯
+ 102 ┤                         ╭─╯
+  99 ┤                       ╭─╯
+  96 ┤                     ╭─╯
+  92 ┤                    ╭╯
+  89 ┤              ╭─────╯
+  86 ┤            ╭─╯
+  83 ┤          ╭─╯
+  80 ┤         ╭╯
+  76 ┤        ╭╯
+  73 ┤ ╭──────╯
+  70 ┼─╯
+          regular_requests_waiting (reqs)
+----
+----
+
+# vim:ft=sh
diff --git a/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/testdata/simulation/over_admission b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/testdata/simulation/over_admission
new file mode 100644
index 000000000000..39b74c681351
--- /dev/null
+++ b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/testdata/simulation/over_admission
@@ -0,0 +1,97 @@
+# Demonstrate how any delay in token deduction after being admitted can lead to
+# over-admission.
+init
+----
+
+# Take away all 16MiB of regular flow tokens; we want a buildup of waiting
+# requests to over-admit from.
+timeline
+start=0s  end=1s  class=regular stream=t1/s1 adjust=-16MiB/s rate=1/s
+----
+
+# Queue 10/s*10s=100 requests for admission, asking for 10*4MiB=40MiB of
+# tokens. For these requests, induce a 2s delay between Admit() and
+# DeductTokens().
+timeline
+start=10s end=20s class=regular stream=t1/s1 adjust=-4MiB/s  rate=10/s deduction-delay=2s
+----
+
+# Return 1KiB of flow tokens at t=30.
+timeline
+start=30s end=31s class=regular stream=t1/s1 adjust=+1KiB/s rate=1/s
+----
+
+simulate end=40s
+----
+
+# Observe how the single 1KiB flow token return ends up admitting all 100
+# waiting requests, over-admitting by 40MiB.
+#
+# TODO(irfansharif): Introduce a "tentative deducted counter" on a per-stream
+# basis, to prevent this kind of over-admission. It's likely to occur any time
+# there's AC queueing due to CPU control, waiting on locks/latches, etc.
+plot start=0s end=40s
+kvadmission.flow_controller.regular_tokens_available  unit=MiB
+kvadmission.flow_controller.regular_requests_admitted unit=reqs/s rate=true
+kvadmission.flow_controller.regular_requests_waiting  unit=reqs
+----
+----
+   0.0 ┼───────────────────────────────╮
+  -2.7 ┤                               │
+  -5.3 ┤                               │
+  -8.0 ┤                               │
+ -10.7 ┤                               │
+ -13.3 ┤                               │
+ -16.0 ┤                               │
+ -18.7 ┤                               │
+ -21.3 ┤                               │
+ -24.0 ┤                               │
+ -26.7 ┤                               │
+ -29.3 ┤                               │
+ -32.0 ┤                               │
+ -34.7 ┤                               │
+ -37.3 ┤                               │
+ -40.0 ┤                               ╰───────
+             regular_tokens_available (MiB)
+
+
+ 100.0 ┤                             ╭╮
+  93.3 ┤                             ││
+  86.7 ┤                             ││
+  80.0 ┤                             ││
+  73.3 ┤                             ││
+  66.7 ┤                             ││
+  60.0 ┤                             ││
+  53.3 ┤                             ││
+  46.7 ┤                             ││
+  40.0 ┤                             ││
+  33.3 ┤                             ││
+  26.7 ┤                             ││
+  20.0 ┤                             ││
+  13.3 ┤                             ││
+   6.7 ┤                             ││
+   0.0 ┼─────────────────────────────╯╰────────
+        rate(regular_requests_admitted) (reqs/s)
+
+
+ 100.0 ┤                   ╭─────────╮
+  93.3 ┤                  ╭╯         │
+  86.7 ┤                 ╭╯          │
+  80.0 ┤                 │           │
+  73.3 ┤                ╭╯           │
+  66.7 ┤               ╭╯            │
+  60.0 ┤               │             │
+  53.3 ┤              ╭╯             │
+  46.7 ┤             ╭╯              │
+  40.0 ┤             │               │
+  33.3 ┤            ╭╯               │
+  26.7 ┤           ╭╯                │
+  20.0 ┤           │                 │
+  13.3 ┤          ╭╯                 │
+   6.7 ┤          │                  │
+   0.0 ┼──────────╯                  ╰─────────
+            regular_requests_waiting (reqs)
+----
+----
+
+# vim:ft=sh
diff --git a/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/testdata/simulation/overview b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/testdata/simulation/overview
new file mode 100644
index 000000000000..a70ee8cd31d4
--- /dev/null
+++ b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/testdata/simulation/overview
@@ -0,0 +1,188 @@
+# Walk through the basics of the datadriven syntax.
+init
+----
+
+# Set up a worker deducting flow tokens at 2MiB/s over 100 reqs/s for regular
+# write work to two stores, s1 and s2. With 16MiB or regular tokens, we expect
+# it to get depleted in 8s. The remaining 8s of incoming work ends up getting
+# queued.
+timeline
+start=0s end=16s class=regular stream=t1/s1 adjust=-2MiB/s rate=100/s
+start=0s end=16s class=regular stream=t1/s2 adjust=-2MiB/s rate=100/s
+----
+
+# Schedule the return of flow tokens at t=20s in similar increments.
+timeline
+start=20s end=36s class=regular stream=t1/s1 adjust=+2MiB/s rate=100/s
+start=20s end=36s class=regular stream=t1/s2 adjust=+2MiB/s rate=100/s
+----
+
+simulate end=40s
+----
+
+# There two replication streams, so we initially have 16*2=32MiB of regular
+# flow tokens and 8*2=16MiB of elastic flow tokens. Since we're not returning
+# flow tokens until t=20s, we deplete them at t=8s. Also note that despite this
+# being regular traffic, we deduct elastic flow tokens for coarse intra-tenant
+# prioritization -- those tokens get depleted at t=4s. Both are deducted at
+# 4MiB/s (2MiB/s for each stream) until we have 0MiB regular tokens and -16MiB
+# elastic tokens.
+plot start=0s end=20s
+kvadmission.flow_controller.{regular,elastic}_tokens_available unit=MiB
+kvadmission.flow_controller.{regular,elastic}_tokens_deducted  unit=MiB/s rate=true
+----
+----
+  32.0 ┼╮
+  28.8 ┤╰─╮
+  25.6 ┤  ╰╮
+  22.4 ┤   ╰─╮
+  19.2 ┤     ╰─╮
+  16.0 ┼╮      ╰╮
+  12.8 ┤╰─╮     ╰─╮
+   9.6 ┤  ╰╮      ╰╮
+   6.4 ┤   ╰─╮     ╰─╮
+   3.2 ┤     ╰─╮     ╰╮
+  -0.0 ┤       ╰╮     ╰────────────────────────
+  -3.2 ┤        ╰─╮
+  -6.4 ┤          ╰╮
+  -9.6 ┤           ╰─╮
+ -12.8 ┤             ╰╮
+ -16.0 ┤              ╰────────────────────────
+        {regular,elastic}_tokens_available (MiB)
+
+
+ 4.0 ┤ ╭─────────────╮
+ 3.7 ┤ │             │
+ 3.5 ┤ │             ╰╮
+ 3.2 ┤ │              │
+ 2.9 ┤ │              │
+ 2.7 ┤ │              │
+ 2.4 ┤ │              │
+ 2.1 ┤ │              │
+ 1.9 ┤ │              │
+ 1.6 ┤ │              │
+ 1.3 ┤ │              ╰╮
+ 1.1 ┤ │               │
+ 0.8 ┤ │               │
+ 0.5 ┤ │               │
+ 0.3 ┤ │               │
+ 0.0 ┼─╯               ╰─────────────────────
+      rate({regular,elastic}_tokens_deducted) (MiB/s)
+----
+----
+
+# Plot the rates at which we (i) admit work when there are flow tokens
+# available, and (ii) enqueue work when there are none. Since we're generating
+# 100 requests/s for two streams, we observe an aggregate admission rate of
+# ~200/s, and then later 200/s of waiting requests growth. There are no
+# errors.
+plot start=0s end=20s
+kvadmission.flow_controller.regular_requests_{admitted,waiting} unit=reqs/s rate=true
+kvadmission.flow_controller.{regular,elastic}_requests_errored  unit=reqs/s rate=true
+----
+----
+ 200 ┤ ╭─────────────╮ ╭─────────────╮
+ 187 ┤ │             │ │             │
+ 173 ┤ │             ╰╮│             │
+ 160 ┤ │              ││             │
+ 147 ┤ │              ││             │
+ 133 ┤ │              ╭╯             ╰╮
+ 120 ┤ │              │               │
+ 107 ┤ │              │               │
+  93 ┤ │              │               │
+  80 ┤ │              │               │
+  67 ┤ │              │╮              │
+  53 ┤ │              ││              │
+  40 ┤ │              ││              │
+  27 ┤ │             ╭╯│              ╰╮
+  13 ┤ │             │ │               │
+   0 ┼───────────────╯ ╰───────────────╰─────
+      rate(regular_requests_{admitted,waiting}) (reqs/s)
+
+
+ 0.0 ┼───────────────────────────────────────
+      rate({regular,elastic}_requests_errored) (reqs/s)
+----
+----
+
+# Confirm that there are two streams underneath, both of which eventually get
+# blocked for {regular,elastic} traffic, with the latter happening first.
+plot start=0s end=20s
+kvadmission.flow_controller.regular_stream_count                   unit=streams
+kvadmission.flow_controller.{regular,elastic}_blocked_stream_count unit=streams
+----
+----
+ 2.0 ┼───────────────────────────────────────
+           regular_stream_count (streams)
+
+
+ 2.0 ┤       ╭───────────────────────────────
+ 1.9 ┤       │       │
+ 1.7 ┤       │       │
+ 1.6 ┤       │       │
+ 1.5 ┤       │       │
+ 1.3 ┤       │       │
+ 1.2 ┤       │       │
+ 1.1 ┤       │       │
+ 0.9 ┤       │       │
+ 0.8 ┤       │       │
+ 0.7 ┤       │       │
+ 0.5 ┤       │       │
+ 0.4 ┤       │       │
+ 0.3 ┤       │       │
+ 0.1 ┤       │       │
+ 0.0 ┼───────╯───────╯
+      {regular,elastic}_blocked_stream_count (streams)
+----
+----
+
+# Observe what happens once flow tokens are returned -- we start admitting work
+# at ~200/s, which matches the rate at which we're reducing the number of
+# waiting requests. By t=36s we'll have returned all {regular,elastic} flow
+# tokens, including for the requests that had to wait for admission.
+plot start=18s end=40s
+kvadmission.flow_controller.regular_requests_{admitted,waiting} unit=reqs/s rate=true
+kvadmission.flow_controller.{regular,elastic}_tokens_available unit=MiB
+----
+----
+  200 ┤     ╭───────────╮
+  175 ┤     │           ╰╮
+  150 ┤    ╭╯            │
+  125 ┤    │             │
+  100 ┤    │             │
+   75 ┤    │             │
+   50 ┤   ╭╯             ╰╮
+   25 ┤   │               │
+    0 ┼───╮               ╭───────────────────
+  -25 ┤   │               │
+  -50 ┤   ╰╮             ╭╯
+  -75 ┤    │             │
+ -100 ┤    │             │
+ -125 ┤    │             │
+ -150 ┤    ╰╮            │
+ -175 ┤     │           ╭╯
+ -200 ┤     ╰───────────╯
+       rate(regular_requests_{admitted,waiting}) (reqs/s)
+
+
+  32.0 ┤                               ╭───────
+  28.8 ┤                             ╭─╯
+  25.6 ┤                            ╭╯
+  22.4 ┤                           ╭╯
+  19.2 ┤                         ╭─╯
+  16.0 ┤                        ╭╯     ╭───────
+  12.8 ┤                      ╭─╯    ╭─╯
+   9.6 ┤                     ╭╯     ╭╯
+   6.4 ┤                   ╭─╯     ╭╯
+   3.2 ┤                  ╭╯     ╭─╯
+  -0.0 ┼──────────────────╯     ╭╯
+  -3.2 ┤                      ╭─╯
+  -6.4 ┤                     ╭╯
+  -9.6 ┤                   ╭─╯
+ -12.8 ┤                  ╭╯
+ -16.0 ┼──────────────────╯
+        {regular,elastic}_tokens_available (MiB)
+----
+----
+
+# vim:ft=sh
diff --git a/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/testdata/simulation/regular_elastic_prioritization b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/testdata/simulation/regular_elastic_prioritization
new file mode 100644
index 000000000000..43df08beebc0
--- /dev/null
+++ b/pkg/kv/kvserver/kvflowcontrol/kvflowcontroller/testdata/simulation/regular_elastic_prioritization
@@ -0,0 +1,122 @@
+# Show that elastic work can get completely starved out by regular work, but
+# not the other way around.
+init
+----
+
+# Kick off two threads, one for each work class, each writing at 1MiB/s over
+# across reqs/s.
+timeline
+start=0s  end=16s class=regular stream=t1/s1 adjust=-1MiB/s rate=100/s
+start=0s  end=8s  class=elastic stream=t1/s1 adjust=-1MiB/s rate=100/s
+----
+
+# start=16s end=32s class=regular stream=t1/s1 adjust=+2MiB/s rate=100/s
+# start=32s end=36s class=elastic stream=t1/s1 adjust=+2MiB/s rate=100/s
+
+simulate
+----
+
+# Observe that initially elastic tokens deplete faster than regular tokens
+# (while elastic tokens > 0MiB), since regular work deducts from both but
+# elastic work only deducts from the elastic bucket. Eventually the rate of
+# elastic token deductions slows down since elastic requests stop being
+# admitted (and thus deducting tokens) once elastic tokens <= 0 MiB. So it's
+# only regular request deductions from that point on. See
+# TestFlowTokenAdjustment for more details.
+plot
+kvadmission.flow_controller.{regular,elastic}_tokens_available  unit=MiB
+----
+  16.0 ┼╮
+  14.1 ┤╰────╮
+  12.3 ┤     ╰───╮
+  10.4 ┤         ╰────╮
+   8.6 ┤              ╰───╮
+   6.7 ┼─╮                ╰────╮
+   4.8 ┤ ╰──╮                  ╰───╮
+   3.0 ┤    ╰─╮                    ╰────╮
+   1.1 ┤      ╰─╮                       ╰───╮
+  -0.7 ┤        ╰───╮                       ╰──
+  -2.6 ┤            ╰───╮
+  -4.5 ┤                ╰────╮
+  -6.3 ┤                     ╰───╮
+  -8.2 ┤                         ╰────╮
+ -10.0 ┤                              ╰───╮
+ -11.9 ┤                                  ╰────
+        {regular,elastic}_tokens_available (MiB)
+
+
+# Confirm that all throughout we're able to admit regular requests at its
+# incoming rate of 100/s. But for elastic requests, once we're out of elastic
+# flow tokens, we stop admitting and start waiting instead. We run of elastic
+# tokens faster since there are fewer of them (8MiB instead of 16MiB), and also
+# they're deducted by both regular and elastic work, compared to regular tokens
+# that are deducted only by regular work.
+plot
+kvadmission.flow_controller.regular_requests_{admitted,waiting} unit=reqs/s rate=true
+kvadmission.flow_controller.elastic_requests_{admitted,waiting} unit=reqs/s rate=true
+----
+----
+ 100.0 ┤  ╭────────────────────────────────────
+  93.3 ┤  │
+  86.7 ┤  │
+  80.0 ┤  │
+  73.3 ┤  │
+  66.7 ┤  │
+  60.0 ┤  │
+  53.3 ┤  │
+  46.7 ┤  │
+  40.0 ┤  │
+  33.3 ┤  │
+  26.7 ┤  │
+  20.0 ┤  │
+  13.3 ┤  │
+   6.7 ┤  │
+   0.0 ┼───────────────────────────────────────
+        rate(regular_requests_{admitted,waiting}) (reqs/s)
+
+
+ 100.0 ┤  ╭──────╮  ╭──────╮
+  93.3 ┤  │      ╰╮╭╯      │
+  86.7 ┤  │       ││       ╰╮
+  80.0 ┤  │       ││        │
+  73.3 ┤  │       ││        │
+  66.7 ┤  │       ││        │
+  60.0 ┤  │       ││        │
+  53.3 ┤  │       ╰│        │
+  46.7 ┤  │       ╭╯        │
+  40.0 ┤  │       ││        ╰╮
+  33.3 ┤  │       ││         │
+  26.7 ┤  │       ││         │
+  20.0 ┤  │       ││         │
+  13.3 ┤  │       ││         │
+   6.7 ┤  │      ╭╯╰╮        │
+   0.0 ┼─────────╯  ╰────────╰─────────────────
+        rate(elastic_requests_{admitted,waiting}) (reqs/s)
+----
+----
+
+# Confirm the above -- when both regular and elastic work gets admitted, we're
+# deducting elastic tokens at 2MiB/s, and at t=4s when elastic work gets
+# blocked, we start deducting at 1MiB/s.
+plot
+kvadmission.flow_controller.elastic_tokens_deducted  unit=MiB rate=true
+----
+ 2.0 ┤  ╭──────╮
+ 1.9 ┤  │      ╰╮
+ 1.7 ┤  │       │
+ 1.6 ┤  │       │
+ 1.5 ┤  │       ╰╮
+ 1.3 ┤  │        │
+ 1.2 ┤  │        │
+ 1.1 ┤  │        ╰───────────────────────────
+ 0.9 ┤  │
+ 0.8 ┤  │
+ 0.7 ┤  │
+ 0.5 ┤  │
+ 0.4 ┤  │
+ 0.3 ┤  │
+ 0.1 ┤  │
+ 0.0 ┼──╯
+        rate(elastic_tokens_deducted) (MiB)
+
+# vim:ft=sh
diff --git a/pkg/util/admission/admissionpb/admissionpb.go b/pkg/util/admission/admissionpb/admissionpb.go
index cd5f4a80dd0a..57dc9911080f 100644
--- a/pkg/util/admission/admissionpb/admissionpb.go
+++ b/pkg/util/admission/admissionpb/admissionpb.go
@@ -10,7 +10,11 @@
 
 package admissionpb
 
-import "math"
+import (
+	"math"
+
+	"github.com/cockroachdb/redact"
+)
 
 // WorkPriority represents the priority of work. In an WorkQueue, it is only
 // used for ordering within a tenant. High priority work can starve lower
@@ -39,6 +43,19 @@ const (
 	OneAboveHighPri int = int(HighPri) + 1
 )
 
+func (w WorkPriority) String() string {
+	return redact.StringWithoutMarkers(w)
+}
+
+// SafeFormat implements the redact.SafeFormatter interface.
+func (w WorkPriority) SafeFormat(p redact.SafePrinter, verb rune) {
+	if s, ok := WorkPriorityDict[w]; ok {
+		p.Print(s)
+		return
+	}
+	p.Printf("custom-pri=%d", w)
+}
+
 // WorkPriorityDict is a mapping of the priorities to a short string name. The
 // name is used as the suffix on exported work queue metrics.
 var WorkPriorityDict = map[WorkPriority]string{
@@ -80,13 +97,18 @@ func WorkClassFromPri(pri WorkPriority) WorkClass {
 }
 
 func (w WorkClass) String() string {
+	return redact.StringWithoutMarkers(w)
+}
+
+// SafeFormat implements the redact.SafeFormatter interface.
+func (w WorkClass) SafeFormat(p redact.SafePrinter, verb rune) {
 	switch w {
 	case RegularWorkClass:
-		return "regular"
+		p.Printf("regular")
 	case ElasticWorkClass:
-		return "elastic"
+		p.Print("elastic")
 	default:
-		return "<unknown>"
+		p.Print("<unknown-class>")
 	}
 }
 
diff --git a/pkg/util/admission/testdata/store_work_queue b/pkg/util/admission/testdata/store_work_queue
index ae615d87acd6..26fba8dc46e4 100644
--- a/pkg/util/admission/testdata/store_work_queue
+++ b/pkg/util/admission/testdata/store_work_queue
@@ -63,7 +63,7 @@ print
 regular workqueue: closed epoch: 0 tenantHeap len: 1 top tenant: 57
  tenant-id: 53 used: 101, w: 1, fifo: -128
  tenant-id: 55 used: 600, w: 1, fifo: -128
- tenant-id: 57 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 0]
+ tenant-id: 57 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 0]
 elastic workqueue: closed epoch: 0 tenantHeap len: 0
 stats:{admittedCount:2 writeAccountedBytes:0 ingestedAccountedBytes:0 statsToIgnore:{IngestOperationStats:{Bytes:0 ApproxIngestedIntoL0Bytes:0}} aux:{bypassedCount:0 writeBypassedAccountedBytes:0 ingestedBypassedAccountedBytes:0}}
 estimates:{writeTokens:100}
diff --git a/pkg/util/admission/testdata/work_queue b/pkg/util/admission/testdata/work_queue
index 3a736dcc48c3..a625fea3755c 100644
--- a/pkg/util/admission/testdata/work_queue
+++ b/pkg/util/admission/testdata/work_queue
@@ -26,7 +26,7 @@ tryGet: returning false
 print
 ----
 closed epoch: 0 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 3, epoch: 0, qt: 100]
+ tenant-id: 53 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 3, epoch: 0, qt: 100]
 
 admit id=3 tenant=53 priority=0 create-time-millis=2 bypass=false
 ----
@@ -36,7 +36,7 @@ admit id=3 tenant=53 priority=0 create-time-millis=2 bypass=false
 print
 ----
 closed epoch: 0 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 2, epoch: 0, qt: 100] [1: pri: 0, ct: 3, epoch: 0, qt: 100]
+ tenant-id: 53 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 2, epoch: 0, qt: 100] [1: pri: normal-pri, ct: 3, epoch: 0, qt: 100]
 
 # Request from tenant 71.
 admit id=4 tenant=71 priority=-128 create-time-millis=4 bypass=false
@@ -51,8 +51,8 @@ admit id=5 tenant=71 priority=0 create-time-millis=5 bypass=false
 print
 ----
 closed epoch: 0 tenantHeap len: 2 top tenant: 71
- tenant-id: 53 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 2, epoch: 0, qt: 100] [1: pri: 0, ct: 3, epoch: 0, qt: 100]
- tenant-id: 71 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 5, epoch: 0, qt: 100] [1: pri: -128, ct: 4, epoch: 0, qt: 100]
+ tenant-id: 53 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 2, epoch: 0, qt: 100] [1: pri: normal-pri, ct: 3, epoch: 0, qt: 100]
+ tenant-id: 71 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 5, epoch: 0, qt: 100] [1: pri: low-pri, ct: 4, epoch: 0, qt: 100]
 
 granted chain-id=5
 ----
@@ -65,8 +65,8 @@ granted: returned 1
 print
 ----
 closed epoch: 0 tenantHeap len: 2 top tenant: 71
- tenant-id: 53 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 2, epoch: 0, qt: 100] [1: pri: 0, ct: 3, epoch: 0, qt: 100]
- tenant-id: 71 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: -128, ct: 4, epoch: 0, qt: 100]
+ tenant-id: 53 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 2, epoch: 0, qt: 100] [1: pri: normal-pri, ct: 3, epoch: 0, qt: 100]
+ tenant-id: 71 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: low-pri, ct: 4, epoch: 0, qt: 100]
 
 # Cancel a request from tenant 53.
 cancel-work id=3
@@ -76,8 +76,8 @@ id 3: admit failed
 print
 ----
 closed epoch: 0 tenantHeap len: 2 top tenant: 71
- tenant-id: 53 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 3, epoch: 0, qt: 100]
- tenant-id: 71 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: -128, ct: 4, epoch: 0, qt: 100]
+ tenant-id: 53 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 3, epoch: 0, qt: 100]
+ tenant-id: 71 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: low-pri, ct: 4, epoch: 0, qt: 100]
 
 # The work admitted for tenant 53 is done.
 work-done id=1
@@ -88,8 +88,8 @@ returnGrant 1
 print
 ----
 closed epoch: 0 tenantHeap len: 2 top tenant: 53
- tenant-id: 53 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 3, epoch: 0, qt: 100]
- tenant-id: 71 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: -128, ct: 4, epoch: 0, qt: 100]
+ tenant-id: 53 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 3, epoch: 0, qt: 100]
+ tenant-id: 71 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: low-pri, ct: 4, epoch: 0, qt: 100]
 
 # A request from the system tenant bypasses admission control, but is
 # reflected in the WorkQueue state.
@@ -102,8 +102,8 @@ print
 ----
 closed epoch: 0 tenantHeap len: 2 top tenant: 53
  tenant-id: 1 used: 1, w: 1, fifo: -128
- tenant-id: 53 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 3, epoch: 0, qt: 100]
- tenant-id: 71 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: -128, ct: 4, epoch: 0, qt: 100]
+ tenant-id: 53 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 3, epoch: 0, qt: 100]
+ tenant-id: 71 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: low-pri, ct: 4, epoch: 0, qt: 100]
 
 granted chain-id=7
 ----
@@ -151,12 +151,12 @@ tryGet: returning false
 advance-time millis=205
 ----
 closed epoch: 2 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 53 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
 
 print
 ----
 closed epoch: 2 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 53 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
 
 granted chain-id=5
 ----
@@ -189,7 +189,7 @@ admit id=4 tenant=53 priority=0 create-time-millis=400 bypass=false
 print
 ----
 closed epoch: 3 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 1, w: 1, fifo: 1 waiting work heap: [0: pri: 0, ct: 399, epoch: 3, qt: 405, lifo-ordering] [1: pri: 0, ct: 50, epoch: 0, qt: 405, lifo-ordering] open epochs heap: [0: pri: 0, ct: 400, epoch: 4, qt: 405]
+ tenant-id: 53 used: 1, w: 1, fifo: 1 waiting work heap: [0: pri: normal-pri, ct: 399, epoch: 3, qt: 405, lifo-ordering] [1: pri: normal-pri, ct: 50, epoch: 0, qt: 405, lifo-ordering] open epochs heap: [0: pri: normal-pri, ct: 400, epoch: 4, qt: 405]
 
 # Latest request in closed epoch is granted.
 granted chain-id=6
@@ -209,7 +209,7 @@ granted: returned 1
 print
 ----
 closed epoch: 3 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 3, w: 1, fifo: 1 open epochs heap: [0: pri: 0, ct: 400, epoch: 4, qt: 405]
+ tenant-id: 53 used: 3, w: 1, fifo: 1 open epochs heap: [0: pri: normal-pri, ct: 400, epoch: 4, qt: 405]
 
 # Add request to closed epoch.
 admit id=5 tenant=53 priority=0 create-time-millis=300 bypass=false
@@ -224,7 +224,7 @@ admit id=6 tenant=53 priority=0 create-time-millis=500 bypass=false
 print
 ----
 closed epoch: 3 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 3, w: 1, fifo: 1 waiting work heap: [0: pri: 0, ct: 300, epoch: 3, qt: 405, lifo-ordering] open epochs heap: [0: pri: 0, ct: 400, epoch: 4, qt: 405] [1: pri: 0, ct: 500, epoch: 5, qt: 405]
+ tenant-id: 53 used: 3, w: 1, fifo: 1 waiting work heap: [0: pri: normal-pri, ct: 300, epoch: 3, qt: 405, lifo-ordering] open epochs heap: [0: pri: normal-pri, ct: 400, epoch: 4, qt: 405] [1: pri: normal-pri, ct: 500, epoch: 5, qt: 405]
 
 # Add high priority request in open epoch 5.
 admit id=7 tenant=53 priority=127 create-time-millis=550 bypass=false
@@ -235,13 +235,13 @@ admit id=7 tenant=53 priority=127 create-time-millis=550 bypass=false
 print
 ----
 closed epoch: 3 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 3, w: 1, fifo: 1 waiting work heap: [0: pri: 127, ct: 550, epoch: 5, qt: 405] [1: pri: 0, ct: 300, epoch: 3, qt: 405, lifo-ordering] open epochs heap: [0: pri: 0, ct: 400, epoch: 4, qt: 405] [1: pri: 0, ct: 500, epoch: 5, qt: 405]
+ tenant-id: 53 used: 3, w: 1, fifo: 1 waiting work heap: [0: pri: high-pri, ct: 550, epoch: 5, qt: 405] [1: pri: normal-pri, ct: 300, epoch: 3, qt: 405, lifo-ordering] open epochs heap: [0: pri: normal-pri, ct: 400, epoch: 4, qt: 405] [1: pri: normal-pri, ct: 500, epoch: 5, qt: 405]
 
 # Make the request wait for 60ms so we don't switch back to fifo.
 advance-time millis=60
 ----
 closed epoch: 3 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 3, w: 1, fifo: 1 waiting work heap: [0: pri: 127, ct: 550, epoch: 5, qt: 405] [1: pri: 0, ct: 300, epoch: 3, qt: 405, lifo-ordering] open epochs heap: [0: pri: 0, ct: 400, epoch: 4, qt: 405] [1: pri: 0, ct: 500, epoch: 5, qt: 405]
+ tenant-id: 53 used: 3, w: 1, fifo: 1 waiting work heap: [0: pri: high-pri, ct: 550, epoch: 5, qt: 405] [1: pri: normal-pri, ct: 300, epoch: 3, qt: 405, lifo-ordering] open epochs heap: [0: pri: normal-pri, ct: 400, epoch: 4, qt: 405] [1: pri: normal-pri, ct: 500, epoch: 5, qt: 405]
 
 granted chain-id=8
 ----
@@ -262,13 +262,13 @@ admit id=8 tenant=53 priority=0 create-time-millis=350 bypass=false
 print
 ----
 closed epoch: 3 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 5, w: 1, fifo: 1 waiting work heap: [0: pri: 0, ct: 350, epoch: 3, qt: 465, lifo-ordering] open epochs heap: [0: pri: 0, ct: 400, epoch: 4, qt: 405] [1: pri: 0, ct: 500, epoch: 5, qt: 405]
+ tenant-id: 53 used: 5, w: 1, fifo: 1 waiting work heap: [0: pri: normal-pri, ct: 350, epoch: 3, qt: 465, lifo-ordering] open epochs heap: [0: pri: normal-pri, ct: 400, epoch: 4, qt: 405] [1: pri: normal-pri, ct: 500, epoch: 5, qt: 405]
 
 # One request moved from open to closed epoch heap.
 advance-time millis=40
 ----
 closed epoch: 4 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 5, w: 1, fifo: 1 waiting work heap: [0: pri: 0, ct: 400, epoch: 4, qt: 405, lifo-ordering] [1: pri: 0, ct: 350, epoch: 3, qt: 465, lifo-ordering] open epochs heap: [0: pri: 0, ct: 500, epoch: 5, qt: 405]
+ tenant-id: 53 used: 5, w: 1, fifo: 1 waiting work heap: [0: pri: normal-pri, ct: 400, epoch: 4, qt: 405, lifo-ordering] [1: pri: normal-pri, ct: 350, epoch: 3, qt: 465, lifo-ordering] open epochs heap: [0: pri: normal-pri, ct: 500, epoch: 5, qt: 405]
 
 granted chain-id=10
 ----
@@ -279,7 +279,7 @@ granted: returned 1
 print
 ----
 closed epoch: 4 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 6, w: 1, fifo: 1 waiting work heap: [0: pri: 0, ct: 350, epoch: 3, qt: 465, lifo-ordering] open epochs heap: [0: pri: 0, ct: 500, epoch: 5, qt: 405]
+ tenant-id: 53 used: 6, w: 1, fifo: 1 waiting work heap: [0: pri: normal-pri, ct: 350, epoch: 3, qt: 465, lifo-ordering] open epochs heap: [0: pri: normal-pri, ct: 500, epoch: 5, qt: 405]
 
 granted chain-id=11
 ----
@@ -290,7 +290,7 @@ granted: returned 1
 print
 ----
 closed epoch: 4 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 7, w: 1, fifo: 1 open epochs heap: [0: pri: 0, ct: 500, epoch: 5, qt: 405]
+ tenant-id: 53 used: 7, w: 1, fifo: 1 open epochs heap: [0: pri: normal-pri, ct: 500, epoch: 5, qt: 405]
 
 # Can dequeue from the open epochs heap if nothing else is remaining.
 granted chain-id=12
@@ -312,13 +312,13 @@ tryGet: returning false
 print
 ----
 closed epoch: 4 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 8, w: 1, fifo: 1 waiting work heap: [0: pri: 0, ct: 380, epoch: 3, qt: 505, lifo-ordering]
+ tenant-id: 53 used: 8, w: 1, fifo: 1 waiting work heap: [0: pri: normal-pri, ct: 380, epoch: 3, qt: 505, lifo-ordering]
 
 # This time advance means the previous request will see significant queueing.
 advance-time millis=100
 ----
 closed epoch: 5 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 8, w: 1, fifo: 1 waiting work heap: [0: pri: 0, ct: 380, epoch: 3, qt: 505, lifo-ordering]
+ tenant-id: 53 used: 8, w: 1, fifo: 1 waiting work heap: [0: pri: normal-pri, ct: 380, epoch: 3, qt: 505, lifo-ordering]
 
 # This request in an already closed epoch gets ahead because of higher
 # create-time-millis.
@@ -328,7 +328,7 @@ admit id=10 tenant=53 priority=0 create-time-millis=390 bypass=false
 print
 ----
 closed epoch: 5 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 8, w: 1, fifo: 1 waiting work heap: [0: pri: 0, ct: 390, epoch: 3, qt: 605, lifo-ordering] [1: pri: 0, ct: 380, epoch: 3, qt: 505, lifo-ordering]
+ tenant-id: 53 used: 8, w: 1, fifo: 1 waiting work heap: [0: pri: normal-pri, ct: 390, epoch: 3, qt: 605, lifo-ordering] [1: pri: normal-pri, ct: 380, epoch: 3, qt: 505, lifo-ordering]
 
 granted chain-id=12
 ----
@@ -339,13 +339,13 @@ granted: returned 1
 print
 ----
 closed epoch: 5 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 9, w: 1, fifo: 1 waiting work heap: [0: pri: 0, ct: 380, epoch: 3, qt: 505, lifo-ordering]
+ tenant-id: 53 used: 9, w: 1, fifo: 1 waiting work heap: [0: pri: normal-pri, ct: 380, epoch: 3, qt: 505, lifo-ordering]
 
 # This advance will switch all priorities back to FIFO.
 advance-time millis=100
 ----
 closed epoch: 6 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 9, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 380, epoch: 3, qt: 505, lifo-ordering]
+ tenant-id: 53 used: 9, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 380, epoch: 3, qt: 505, lifo-ordering]
 
 admit id=11 tenant=53 priority=0 create-time-millis=610 bypass=false
 ----
@@ -359,7 +359,7 @@ admit id=12 tenant=53 priority=-128 create-time-millis=615 bypass=false
 print
 ----
 closed epoch: 6 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 9, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 610, epoch: 6, qt: 705] [1: pri: 0, ct: 380, epoch: 3, qt: 505, lifo-ordering] [2: pri: -128, ct: 615, epoch: 6, qt: 705]
+ tenant-id: 53 used: 9, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 610, epoch: 6, qt: 705] [1: pri: normal-pri, ct: 380, epoch: 3, qt: 505, lifo-ordering] [2: pri: low-pri, ct: 615, epoch: 6, qt: 705]
 
 granted chain-id=13
 ----
@@ -372,7 +372,7 @@ granted: returned 1
 print
 ----
 closed epoch: 6 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 10, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 380, epoch: 3, qt: 505, lifo-ordering] [1: pri: -128, ct: 615, epoch: 6, qt: 705]
+ tenant-id: 53 used: 10, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 380, epoch: 3, qt: 505, lifo-ordering] [1: pri: low-pri, ct: 615, epoch: 6, qt: 705]
 
 granted chain-id=14
 ----
@@ -401,7 +401,7 @@ tryGet: returning false
 print
 ----
 closed epoch: 7 tenantHeap len: 1 top tenant: 53
- tenant-id: 53 used: 12, w: 1, fifo: 1 open epochs heap: [0: pri: 0, ct: 810, epoch: 8, qt: 805]
+ tenant-id: 53 used: 12, w: 1, fifo: 1 open epochs heap: [0: pri: normal-pri, ct: 810, epoch: 8, qt: 805]
 
 # Cancel that request.
 cancel-work id=13
@@ -446,19 +446,19 @@ tryGet: returning false
 print
 ----
 closed epoch: 0 tenantHeap len: 1 top tenant: 5
- tenant-id: 5 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 5 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
 
 # Weight is unchanged for tenant 5.
 set-tenant-weights weights=10:11
 ----
 closed epoch: 0 tenantHeap len: 1 top tenant: 5
- tenant-id: 5 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 5 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
 
 # Now tenant 5 has a new weight.
 set-tenant-weights weights=5:6,10:11
 ----
 closed epoch: 0 tenantHeap len: 1 top tenant: 5
- tenant-id: 5 used: 0, w: 6, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 5 used: 0, w: 6, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
 
 admit id=2 tenant=10 priority=0 create-time-millis=1 bypass=false
 ----
@@ -466,8 +466,8 @@ admit id=2 tenant=10 priority=0 create-time-millis=1 bypass=false
 print
 ----
 closed epoch: 0 tenantHeap len: 2 top tenant: 5
- tenant-id: 5 used: 0, w: 6, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 10 used: 0, w: 11, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 5 used: 0, w: 6, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 10 used: 0, w: 11, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
 
 granted chain-id=1
 ----
@@ -500,8 +500,8 @@ admit id=4 tenant=10 priority=0 create-time-millis=1 bypass=false
 print
 ----
 closed epoch: 0 tenantHeap len: 2 top tenant: 10
- tenant-id: 5 used: 1, w: 6, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 10 used: 1, w: 11, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 5 used: 1, w: 6, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 10 used: 1, w: 11, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
 
 # Grant to tenant 10 so it is using 2 slots.
 granted chain-id=3
@@ -513,7 +513,7 @@ granted: returned 1
 print
 ----
 closed epoch: 0 tenantHeap len: 1 top tenant: 5
- tenant-id: 5 used: 1, w: 6, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 5 used: 1, w: 6, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
  tenant-id: 10 used: 2, w: 11, fifo: -128
 
 # Another request from tenant 10.
@@ -524,8 +524,8 @@ admit id=5 tenant=10 priority=0 create-time-millis=1 bypass=false
 print
 ----
 closed epoch: 0 tenantHeap len: 2 top tenant: 5
- tenant-id: 5 used: 1, w: 6, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 10 used: 2, w: 11, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 5 used: 1, w: 6, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 10 used: 2, w: 11, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
 
 # Increase tenant 10's weight so it becomes the top of the heap. Weight
 # scaling is also applied here to make the max weight 20, and reduce tenant
@@ -533,22 +533,22 @@ closed epoch: 0 tenantHeap len: 2 top tenant: 5
 set-tenant-weights weights=5:6,10:30
 ----
 closed epoch: 0 tenantHeap len: 2 top tenant: 10
- tenant-id: 5 used: 1, w: 4, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 10 used: 2, w: 20, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 5 used: 1, w: 4, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 10 used: 2, w: 20, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
 
 # Restore all weights to 1. Tenant 5 is now top of the heap.
 set-tenant-weights weights=5:1,10:1
 ----
 closed epoch: 0 tenantHeap len: 2 top tenant: 5
- tenant-id: 5 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 10 used: 2, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 5 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 10 used: 2, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
 
 # Adjust weights to make tenant 10 just slightly preferable over tenant 5.
 set-tenant-weights weights=5:6,10:13
 ----
 closed epoch: 0 tenantHeap len: 2 top tenant: 10
- tenant-id: 5 used: 1, w: 6, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 10 used: 2, w: 13, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 5 used: 1, w: 6, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 10 used: 2, w: 13, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
 
 # Add another request for tenant 10.
 admit id=6 tenant=10 priority=0 create-time-millis=1 bypass=false
@@ -565,16 +565,16 @@ granted: returned 1
 print
 ----
 closed epoch: 0 tenantHeap len: 2 top tenant: 5
- tenant-id: 5 used: 1, w: 6, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 10 used: 3, w: 13, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 5 used: 1, w: 6, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 10 used: 3, w: 13, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
 
 # Bump up tenant 10's weight to a huge value. Tenant 5's weight is not scaled
 # down to 0, since the minimum weight is 1.
 set-tenant-weights weights=5:1,10:100000
 ----
 closed epoch: 0 tenantHeap len: 2 top tenant: 10
- tenant-id: 5 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 10 used: 3, w: 20, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 5 used: 1, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 10 used: 3, w: 20, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
 
 granted chain-id=5
 ----
@@ -623,27 +623,27 @@ admit id=8 tenant=8 priority=0 create-time-millis=1 bypass=false
 print
 ----
 closed epoch: 0 tenantHeap len: 8 top tenant: 1
- tenant-id: 1 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 2 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 3 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 4 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 5 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 6 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 7 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 8 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 1 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 2 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 3 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 4 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 5 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 6 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 7 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 8 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
 
 # Set weights for 7 out of the 8 tenants.
 set-tenant-weights weights=1:2,2:3,3:4,4:5,5:6,7:8,8:9
 ----
 closed epoch: 0 tenantHeap len: 8 top tenant: 1
- tenant-id: 1 used: 0, w: 2, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 2 used: 0, w: 3, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 3 used: 0, w: 4, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 4 used: 0, w: 5, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 5 used: 0, w: 6, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 6 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 7 used: 0, w: 8, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
- tenant-id: 8 used: 0, w: 9, fifo: -128 waiting work heap: [0: pri: 0, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 1 used: 0, w: 2, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 2 used: 0, w: 3, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 3 used: 0, w: 4, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 4 used: 0, w: 5, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 5 used: 0, w: 6, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 6 used: 0, w: 1, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 7 used: 0, w: 8, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
+ tenant-id: 8 used: 0, w: 9, fifo: -128 waiting work heap: [0: pri: normal-pri, ct: 1, epoch: 0, qt: 100]
 
 granted chain-id=1
 ----
diff --git a/pkg/util/asciitsdb/BUILD.bazel b/pkg/util/asciitsdb/BUILD.bazel
new file mode 100644
index 000000000000..8a81a4c655cc
--- /dev/null
+++ b/pkg/util/asciitsdb/BUILD.bazel
@@ -0,0 +1,18 @@
+load("//build/bazelutil/unused_checker:unused.bzl", "get_x_data")
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "asciitsdb",
+    srcs = ["asciitsdb.go"],
+    importpath = "github.com/cockroachdb/cockroach/pkg/util/asciitsdb",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//pkg/util/log",
+        "//pkg/util/metric",
+        "//pkg/util/syncutil",
+        "@com_github_guptarohit_asciigraph//:asciigraph",
+        "@com_github_stretchr_testify//require",
+    ],
+)
+
+get_x_data(name = "get_x_data")
diff --git a/pkg/util/asciitsdb/asciitsdb.go b/pkg/util/asciitsdb/asciitsdb.go
new file mode 100644
index 000000000000..a5d0918f3975
--- /dev/null
+++ b/pkg/util/asciitsdb/asciitsdb.go
@@ -0,0 +1,311 @@
+// Copyright 2023 The Cockroach Authors.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+package asciitsdb
+
+import (
+	"context"
+	"fmt"
+	"math"
+	"reflect"
+	"testing"
+
+	"github.com/cockroachdb/cockroach/pkg/util/log"
+	"github.com/cockroachdb/cockroach/pkg/util/metric"
+	"github.com/cockroachdb/cockroach/pkg/util/syncutil"
+	"github.com/guptarohit/asciigraph"
+	"github.com/stretchr/testify/require"
+)
+
+// TSDB is used to plot ASCII timeseries for tests that want to observe how CRDB
+// metrics behave.
+type TSDB struct {
+	t   *testing.T
+	reg *metric.Registry
+
+	mu struct {
+		syncutil.Mutex
+		scraped bool
+		points  map[string][]float64 // registered metric name => scraped data points
+	}
+}
+
+// New returns a new ASCII TSDB.
+func New(t *testing.T, reg *metric.Registry) *TSDB {
+	tsdb := &TSDB{t: t, reg: reg}
+	tsdb.mu.points = make(map[string][]float64)
+	return tsdb
+}
+
+// Register registers a metric struct for plotting. For histograms, we follow
+// CRDB's internal TSDB naming conventions, i.e. we export values for:
+// - {metric name}-count
+// - {metric name}-avg
+// - {metric name}-max
+// - {metric name}-p99
+// - {metric name}-p90
+// - {metric name}-p75
+// - {metric name}-p50
+func (t *TSDB) Register(mstruct interface{}) {
+	// NB: This code was cargo culted from the metric registry's
+	// AddStruct method.
+
+	v := reflect.ValueOf(mstruct)
+	if v.Kind() == reflect.Ptr {
+		v = v.Elem()
+	}
+	typ := v.Type()
+
+	for i := 0; i < v.NumField(); i++ {
+		vfield, tfield := v.Field(i), typ.Field(i)
+		tname := tfield.Name
+		if !vfield.CanInterface() {
+			t.t.Logf("skipping unexported field %s", tname)
+			continue
+		}
+		switch vfield.Kind() {
+		case reflect.Array:
+			for i := 0; i < vfield.Len(); i++ {
+				velem := vfield.Index(i)
+				telemName := fmt.Sprintf("%s[%d]", tname, i)
+				// Permit elements in the array to be nil.
+				const skipNil = true
+				t.registerMetricValue(velem, telemName, skipNil)
+			}
+		default:
+			// No metric fields should be nil.
+			const skipNil = false
+			t.registerMetricValue(vfield, tname, skipNil)
+		}
+	}
+}
+
+// Scrape all registered metrics. It records a single data point for all
+// registered metrics.
+func (t *TSDB) Scrape(ctx context.Context) {
+	// TB: This code is cargo culted entirely from the TSDB scraper.
+
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	t.mu.scraped = true
+
+	t.reg.Each(func(name string, val interface{}) {
+		if _, ok := t.mu.points[name]; !ok {
+			return
+		}
+
+		switch mtr := val.(type) {
+		case metric.WindowedHistogram:
+			n := float64(mtr.TotalCountWindowed())
+			if _, ok := t.mu.points[name]; !ok {
+				return
+			}
+			t.mu.points[name+"-count"] = append(t.mu.points[name+"-count"], n)
+			avg := mtr.TotalSumWindowed() / n
+			if math.IsNaN(avg) || math.IsInf(avg, +1) || math.IsInf(avg, -1) {
+				avg = 0
+			}
+			t.mu.points[name+"-avg"] = append(t.mu.points[name+"-avg"], avg)
+			for _, pt := range []quantile{
+				{"-max", 100},
+				{"-p99", 99},
+				{"-p90", 90},
+				{"-p75", 75},
+				{"-p50", 50},
+			} {
+				t.mu.points[name+pt.suffix] = append(t.mu.points[name+pt.suffix], mtr.ValueAtQuantileWindowed(pt.quantile))
+			}
+		case metric.PrometheusExportable:
+			// NB: this branch is intentionally at the bottom since all metrics
+			// implement it.
+			m := mtr.ToPrometheusMetric()
+			if m.Gauge != nil {
+				t.mu.points[name] = append(t.mu.points[name], *m.Gauge.Value)
+			} else if m.Counter != nil {
+				t.mu.points[name] = append(t.mu.points[name], *m.Counter.Value)
+			}
+		default:
+			log.Fatalf(ctx, "cannot extract value for type %T", mtr)
+		}
+	})
+}
+
+// Plot plots the given metrics, using the given options.
+func (t *TSDB) Plot(metrics []string, options ...Option) string {
+	c := configure(config{
+		limit: math.MaxInt,
+	}, options)
+
+	var plots [][]float64
+	for _, metric := range metrics {
+		points, ok := t.read(metric)
+		require.Truef(t.t, ok, "%s not found", metric)
+		if c.rate != 0 {
+			points = rate(points, c.rate)
+		}
+		if c.divisor != 0 {
+			points = divide(points, c.divisor)
+		}
+		c.limit = min(c.limit, int64(len(points))-c.offset)
+		points = points[c.offset : c.offset+c.limit]
+		plots = append(plots, points)
+	}
+	return asciigraph.PlotMany(plots, c.graphopts...)
+}
+
+// Clear all recorded data points.
+func (t *TSDB) Clear() {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	for metric := range t.mu.points {
+		t.mu.points[metric] = nil
+	}
+}
+
+// read reads all data points for the given metric name.
+func (t *TSDB) read(metric string) ([]float64, bool) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	points, ok := t.mu.points[metric]
+	return points, ok
+}
+
+func (t *TSDB) registerMetricValue(val reflect.Value, name string, skipNil bool) {
+	if val.Kind() == reflect.Ptr && val.IsNil() {
+		if skipNil {
+			t.t.Logf("skipping nil metric field %s", name)
+		} else {
+			t.t.Fatalf("found nil metric field %s", name)
+		}
+		return
+	}
+	switch typ := val.Interface().(type) {
+	case metric.Iterable:
+		t.registerIterable(typ)
+	case metric.Struct:
+		t.Register(typ)
+	default:
+		t.t.Logf("skipping non-metric field %s", name)
+	}
+}
+
+func (t *TSDB) registerIterable(metric metric.Iterable) {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if t.mu.scraped {
+		t.t.Fatalf("register all metrics upfront before Scrape()")
+	}
+	t.mu.points[metric.GetName()] = []float64{}
+}
+
+// Option represents a configuration setting.
+type Option interface {
+	apply(c *config)
+}
+
+// WithRate plots the rate of growth for a given metric. The parameter is used
+// to control how far back (with respect to individual points) compute the delta
+// over.
+func WithRate(r int) Option {
+	return optionFunc(func(c *config) {
+		c.rate = r
+	})
+}
+
+// WithDivisor divides all individual points of a metric by the given divisor.
+func WithDivisor(d float64) Option {
+	return optionFunc(func(c *config) {
+		c.divisor = d
+	})
+}
+
+// WithGraphOptions configures the look and feel of the generated ASCII graphs.
+func WithGraphOptions(opts ...asciigraph.Option) Option {
+	return optionFunc(func(c *config) {
+		c.graphopts = opts
+	})
+}
+
+// WithOffset is used to offset a specified number of points in the graph.
+func WithOffset(o int64) Option {
+	return optionFunc(func(c *config) {
+		c.offset = o
+	})
+}
+
+// WithLimit is used to limit the number of points in the graph.
+func WithLimit(l int64) Option {
+	return optionFunc(func(c *config) {
+		c.limit = l
+	})
+}
+
+// config holds the various graphing options.
+type config struct {
+	rate          int
+	divisor       float64
+	offset, limit int64
+	graphopts     []asciigraph.Option
+}
+
+// An optionFunc applies an option.
+type optionFunc func(*config)
+
+// apply implements the Option interface.
+func (of optionFunc) apply(c *config) { of(c) }
+
+func configure(defaults config, options []Option) *config {
+	for _, o := range options {
+		o.apply(&defaults)
+	}
+	return &defaults
+}
+
+// rate takes a list of individual data points (typically read from a cumulative
+// counter) and returns a derivative, computed simply by taking each
+// corresponding input point and subtracting one r points ago. If r points are
+// collected per-{time unit}, this ends up computing the rate of growth
+// per-{time unit}.
+func rate(input []float64, r int) []float64 {
+	rated := make([]float64, len(input))
+	for i := 0; i < len(input); i++ {
+		if i < r {
+			rated[i] = 0
+			continue
+		}
+
+		delta := input[i] - input[i-r]
+		rated[i] = delta
+	}
+	return rated
+}
+
+// divide takes a list of individual data points and returns another, where each
+// point is the corresponding input divided by the divisor.
+func divide(input []float64, divisor float64) []float64 {
+	output := make([]float64, len(input))
+	for i := 0; i < len(input); i++ {
+		output[i] = input[i] / divisor
+	}
+	return output
+}
+
+type quantile struct {
+	suffix   string
+	quantile float64
+}
+
+func min(i, j int64) int64 {
+	if i < j {
+		return i
+	}
+	return j
+}