Illumos 4976-4984 - metaslab improvements

4976 zfs should only avoid writing to a failing non-redundant top-level vdev
4978 ztest fails in get_metaslab_refcount()
4979 extend free space histogram to device and pool
4980 metaslabs should have a fragmentation metric
4981 remove fragmented ops vector from block allocator
4982 space_map object should proactively upgrade when feature is enabled
4983 need to collect metaslab information via mdb
4984 device selection should use fragmentation metric
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Adam Leventhal <adam.leventhal@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Approved by: Garrett D'Amore <garrett@damore.org>

References:
  https://www.illumos.org/issues/4976
  https://www.illumos.org/issues/4978
  https://www.illumos.org/issues/4979
  https://www.illumos.org/issues/4980
  https://www.illumos.org/issues/4981
  https://www.illumos.org/issues/4982
  https://www.illumos.org/issues/4983
  https://www.illumos.org/issues/4984
  illumos/illumos-gate@2e4c998

Notes:
    The "zdb -M" option has been re-tasked to display the new metaslab
    fragmentation metric and the new "zdb -I" option is used to control
    the maximum number of in-flight I/Os.

    The new fragmentation metric is derived from the space map histogram
    which has been rolled up to the vdev and pool level and is presented
    to the user via "zpool list".

    Add a number of module parameters related to the new metaslab weighting
    logic.

Ported by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #2595

cmd/zdb/zdb.c

@@ -110,11 +110,11 @@ static void
 usage(void)
 {
 	(void) fprintf(stderr,
-	    "Usage: %s [-CumdibcsDvhLXFPA] [-t txg] [-e [-p path...]] "
-	    "[-U config] [-M inflight I/Os] poolname [object...]\n"
+	    "Usage: %s [-CumMdibcsDvhLXFPA] [-t txg] [-e [-p path...]] "
+	    "[-U config] [-I inflight I/Os] poolname [object...]\n"
 	    "       %s [-divPA] [-e -p path...] [-U config] dataset "
 	    "[object...]\n"
-	    "       %s -m [-LXFPA] [-t txg] [-e [-p path...]] [-U config] "
+	    "       %s -mM [-LXFPA] [-t txg] [-e [-p path...]] [-U config] "
 	    "poolname [vdev [metaslab...]]\n"
 	    "       %s -R [-A] [-e [-p path...]] poolname "
 	    "vdev:offset:size[:flags]\n"
@@ -137,6 +137,7 @@ usage(void)
 	(void) fprintf(stderr, "        -h pool history\n");
 	(void) fprintf(stderr, "        -b block statistics\n");
 	(void) fprintf(stderr, "        -m metaslabs\n");
+	(void) fprintf(stderr, "        -M metaslab groups\n");
 	(void) fprintf(stderr, "        -c checksum all metadata (twice for "
 	    "all data) blocks\n");
 	(void) fprintf(stderr, "        -s report stats on zdb's I/O\n");
@@ -165,7 +166,7 @@ usage(void)
 	(void) fprintf(stderr, "        -P print numbers in parseable form\n");
 	(void) fprintf(stderr, "        -t <txg> -- highest txg to use when "
 	    "searching for uberblocks\n");
-	(void) fprintf(stderr, "        -M <number of inflight I/Os> -- "
+	(void) fprintf(stderr, "        -I <number of inflight I/Os> -- "
 	    "specify the maximum number of checksumming I/Os "
 	    "[default is 200]\n");
 	(void) fprintf(stderr, "Specify an option more than once (e.g. -bb) "
@@ -547,7 +548,7 @@ get_metaslab_refcount(vdev_t *vd)
 	int refcount = 0;
 	int c, m;
 
-	if (vd->vdev_top == vd) {
+	if (vd->vdev_top == vd && !vd->vdev_removing) {
 		for (m = 0; m < vd->vdev_ms_count; m++) {
 			space_map_t *sm = vd->vdev_ms[m]->ms_sm;
 
@@ -685,9 +686,10 @@ dump_metaslab(metaslab_t *msp)
 		 * The space map histogram represents free space in chunks
 		 * of sm_shift (i.e. bucket 0 refers to 2^sm_shift).
 		 */
-		(void) printf("\tOn-disk histogram:\n");
+		(void) printf("\tOn-disk histogram:\t\tfragmentation %llu\n",
+		    (u_longlong_t)msp->ms_fragmentation);
 		dump_histogram(sm->sm_phys->smp_histogram,
-		    SPACE_MAP_HISTOGRAM_SIZE(sm), sm->sm_shift);
+		    SPACE_MAP_HISTOGRAM_SIZE, sm->sm_shift);
 	}
 
 	if (dump_opt['d'] > 5 || dump_opt['m'] > 3) {
@@ -711,6 +713,48 @@ print_vdev_metaslab_header(vdev_t *vd)
 	    "---------------", "-------------");
 }
 
+static void
+dump_metaslab_groups(spa_t *spa)
+{
+	vdev_t *rvd = spa->spa_root_vdev;
+	metaslab_class_t *mc = spa_normal_class(spa);
+	uint64_t fragmentation;
+	int c;
+
+	metaslab_class_histogram_verify(mc);
+
+	for (c = 0; c < rvd->vdev_children; c++) {
+		vdev_t *tvd = rvd->vdev_child[c];
+		metaslab_group_t *mg = tvd->vdev_mg;
+
+		if (mg->mg_class != mc)
+			continue;
+
+		metaslab_group_histogram_verify(mg);
+		mg->mg_fragmentation = metaslab_group_fragmentation(mg);
+
+		(void) printf("\tvdev %10llu\t\tmetaslabs%5llu\t\t"
+		    "fragmentation",
+		    (u_longlong_t)tvd->vdev_id,
+		    (u_longlong_t)tvd->vdev_ms_count);
+		if (mg->mg_fragmentation == ZFS_FRAG_INVALID) {
+			(void) printf("%3s\n", "-");
+		} else {
+			(void) printf("%3llu%%\n",
+			    (u_longlong_t)mg->mg_fragmentation);
+		}
+		dump_histogram(mg->mg_histogram, RANGE_TREE_HISTOGRAM_SIZE, 0);
+	}
+
+	(void) printf("\tpool %s\tfragmentation", spa_name(spa));
+	fragmentation = metaslab_class_fragmentation(mc);
+	if (fragmentation == ZFS_FRAG_INVALID)
+		(void) printf("\t%3s\n", "-");
+	else
+		(void) printf("\t%3llu%%\n", (u_longlong_t)fragmentation);
+	dump_histogram(mc->mc_histogram, RANGE_TREE_HISTOGRAM_SIZE, 0);
+}
+
 static void
 dump_metaslabs(spa_t *spa)
 {
@@ -2381,8 +2425,7 @@ zdb_leak(void *arg, uint64_t start, uint64_t size)
 }
 
 static metaslab_ops_t zdb_metaslab_ops = {
-	NULL,	/* alloc */
-	NULL	/* fragmented */
+	NULL	/* alloc */
 };
 
 static void
@@ -2874,6 +2917,8 @@ dump_zpool(spa_t *spa)
 
 	if (dump_opt['d'] > 2 || dump_opt['m'])
 		dump_metaslabs(spa);
+	if (dump_opt['M'])
+		dump_metaslab_groups(spa);
 
 	if (dump_opt['d'] || dump_opt['i']) {
 		dump_dir(dp->dp_meta_objset);
@@ -3363,7 +3408,7 @@ main(int argc, char **argv)
 	int flags = ZFS_IMPORT_MISSING_LOG;
 	int rewind = ZPOOL_NEVER_REWIND;
 	char *spa_config_path_env;
-	const char *opts = "bcdhilmM:suCDRSAFLVXevp:t:U:P";
+	const char *opts = "bcdhilmMI:suCDRSAFLXevp:t:U:P";
 
 	(void) setrlimit(RLIMIT_NOFILE, &rl);
 	(void) enable_extended_FILE_stdio(-1, -1);
@@ -3392,6 +3437,7 @@ main(int argc, char **argv)
 		case 'u':
 		case 'C':
 		case 'D':
+		case 'M':
 		case 'R':
 		case 'S':
 			dump_opt[c]++;
@@ -3408,10 +3454,7 @@ main(int argc, char **argv)
 		case 'V':
 			flags = ZFS_IMPORT_VERBATIM;
 			break;
-		case 'v':
-			verbose++;
-			break;
-		case 'M':
+		case 'I':
 			max_inflight = strtoull(optarg, NULL, 0);
 			if (max_inflight == 0) {
 				(void) fprintf(stderr, "maximum number "
@@ -3446,6 +3489,9 @@ main(int argc, char **argv)
 		case 'U':
 			spa_config_path = optarg;
 			break;
+		case 'v':
+			verbose++;
+			break;
 		default:
 			usage();
 			break;

cmd/zpool/zpool_main.c

@@ -2998,10 +2998,16 @@ print_one_column(zpool_prop_t prop, uint64_t value, boolean_t scripted)
 	boolean_t fixed;
 	size_t width = zprop_width(prop, &fixed, ZFS_TYPE_POOL);
 
-	zfs_nicenum(value, propval, sizeof (propval));
 
 	if (prop == ZPOOL_PROP_EXPANDSZ && value == 0)
 		(void) strlcpy(propval, "-", sizeof (propval));
+	else if (prop == ZPOOL_PROP_FRAGMENTATION && value == ZFS_FRAG_INVALID)
+		(void) strlcpy(propval, "-", sizeof (propval));
+	else if (prop == ZPOOL_PROP_FRAGMENTATION)
+		(void) snprintf(propval, sizeof (propval), "%llu%%",
+		    (unsigned long long)value);
+	else
+		zfs_nicenum(value, propval, sizeof (propval));
 
 	if (scripted)
 		(void) printf("\t%s", propval);
@@ -3034,16 +3040,18 @@ print_list_stats(zpool_handle_t *zhp, const char *name, nvlist_t *nv,
 		/* only toplevel vdevs have capacity stats */
 		if (vs->vs_space == 0) {
 			if (scripted)
-				(void) printf("\t-\t-\t-");
+				(void) printf("\t-\t-\t-\t-");
 			else
-				(void) printf("      -      -      -");
+				(void) printf("      -      -      -      -");
 		} else {
 			print_one_column(ZPOOL_PROP_SIZE, vs->vs_space,
 			    scripted);
 			print_one_column(ZPOOL_PROP_CAPACITY, vs->vs_alloc,
 			    scripted);
 			print_one_column(ZPOOL_PROP_FREE,
 			    vs->vs_space - vs->vs_alloc, scripted);
+			print_one_column(ZPOOL_PROP_FRAGMENTATION,
+			    vs->vs_fragmentation, scripted);
 		}
 		print_one_column(ZPOOL_PROP_EXPANDSZ, vs->vs_esize,
 		    scripted);
@@ -3128,8 +3136,8 @@ zpool_do_list(int argc, char **argv)
 	int ret = 0;
 	list_cbdata_t cb = { 0 };
 	static char default_props[] =
-	    "name,size,allocated,free,capacity,dedupratio,"
-	    "health,altroot";
+	    "name,size,allocated,free,fragmentation,capacity,"
+	    "dedupratio,health,altroot";
 	char *props = default_props;
 	unsigned long interval = 0, count = 0;
 	zpool_list_t *list;

include/sys/fs/zfs.h

@@ -194,6 +194,7 @@ typedef enum {
 	ZPOOL_PROP_COMMENT,
 	ZPOOL_PROP_EXPANDSZ,
 	ZPOOL_PROP_FREEING,
+	ZPOOL_PROP_FRAGMENTATION,
 	ZPOOL_PROP_LEAKED,
 	ZPOOL_NUM_PROPS
 } zpool_prop_t;
@@ -599,6 +600,13 @@ typedef struct zpool_rewind_policy {
  */
 #define	SPA_MINDEVSIZE		(64ULL << 20)
 
+/*
+ * Set if the fragmentation has not yet been calculated. This can happen
+ * because the space maps have not been upgraded or the histogram feature
+ * is not enabled.
+ */
+#define	ZFS_FRAG_INVALID	UINT64_MAX
+
 /*
  * The location of the pool configuration repository, shared between kernel and
  * userland.
@@ -747,6 +755,7 @@ typedef struct vdev_stat {
 	uint64_t	vs_self_healed;		/* self-healed bytes	*/
 	uint64_t	vs_scan_removing;	/* removing?	*/
 	uint64_t	vs_scan_processed;	/* scan processed bytes	*/
+	uint64_t	vs_fragmentation;	/* device fragmentation */
 } vdev_stat_t;
 
 /*

include/sys/metaslab.h

@@ -20,7 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
- * Copyright (c) 2013 by Delphix. All rights reserved.
+ * Copyright (c) 2011, 2014 by Delphix. All rights reserved.
  */
 
 #ifndef _SYS_METASLAB_H
@@ -38,23 +38,22 @@ extern "C" {
 
 typedef struct metaslab_ops {
 	uint64_t (*msop_alloc)(metaslab_t *msp, uint64_t size);
-	boolean_t (*msop_fragmented)(metaslab_t *msp);
 } metaslab_ops_t;
 
 extern metaslab_ops_t *zfs_metaslab_ops;
 
-metaslab_t *metaslab_init(metaslab_group_t *mg, uint64_t id,
-    uint64_t object, uint64_t txg);
-void metaslab_fini(metaslab_t *msp);
+metaslab_t *metaslab_init(metaslab_group_t *, uint64_t,
+    uint64_t, uint64_t);
+void metaslab_fini(metaslab_t *);
 
-void metaslab_load_wait(metaslab_t *msp);
-int metaslab_load(metaslab_t *msp);
-void metaslab_unload(metaslab_t *msp);
+void metaslab_load_wait(metaslab_t *);
+int metaslab_load(metaslab_t *);
+void metaslab_unload(metaslab_t *);
 
-void metaslab_sync(metaslab_t *msp, uint64_t txg);
-void metaslab_sync_done(metaslab_t *msp, uint64_t txg);
-void metaslab_sync_reassess(metaslab_group_t *mg);
-uint64_t metaslab_block_maxsize(metaslab_t *msp);
+void metaslab_sync(metaslab_t *, uint64_t);
+void metaslab_sync_done(metaslab_t *, uint64_t);
+void metaslab_sync_reassess(metaslab_group_t *);
+uint64_t metaslab_block_maxsize(metaslab_t *);
 
 #define	METASLAB_HINTBP_FAVOR	0x0
 #define	METASLAB_HINTBP_AVOID	0x1
@@ -63,30 +62,36 @@ uint64_t metaslab_block_maxsize(metaslab_t *msp);
 #define	METASLAB_GANG_AVOID	0x8
 #define	METASLAB_FASTWRITE	0x10
 
-int metaslab_alloc(spa_t *spa, metaslab_class_t *mc, uint64_t psize,
-    blkptr_t *bp, int ncopies, uint64_t txg, blkptr_t *hintbp, int flags);
-void metaslab_free(spa_t *spa, const blkptr_t *bp, uint64_t txg, boolean_t now);
-int metaslab_claim(spa_t *spa, const blkptr_t *bp, uint64_t txg);
-void metaslab_check_free(spa_t *spa, const blkptr_t *bp);
-void metaslab_fastwrite_mark(spa_t *spa, const blkptr_t *bp);
-void metaslab_fastwrite_unmark(spa_t *spa, const blkptr_t *bp);
+int metaslab_alloc(spa_t *, metaslab_class_t *, uint64_t,
+    blkptr_t *, int, uint64_t, blkptr_t *, int);
+void metaslab_free(spa_t *, const blkptr_t *, uint64_t, boolean_t);
+int metaslab_claim(spa_t *, const blkptr_t *, uint64_t);
+void metaslab_check_free(spa_t *, const blkptr_t *);
+void metaslab_fastwrite_mark(spa_t *, const blkptr_t *);
+void metaslab_fastwrite_unmark(spa_t *, const blkptr_t *);
 
-metaslab_class_t *metaslab_class_create(spa_t *spa, metaslab_ops_t *ops);
-void metaslab_class_destroy(metaslab_class_t *mc);
-int metaslab_class_validate(metaslab_class_t *mc);
+metaslab_class_t *metaslab_class_create(spa_t *, metaslab_ops_t *);
+void metaslab_class_destroy(metaslab_class_t *);
+int metaslab_class_validate(metaslab_class_t *);
+void metaslab_class_histogram_verify(metaslab_class_t *);
+uint64_t metaslab_class_fragmentation(metaslab_class_t *);
+uint64_t metaslab_class_expandable_space(metaslab_class_t *);
 
-void metaslab_class_space_update(metaslab_class_t *mc,
-    int64_t alloc_delta, int64_t defer_delta,
-    int64_t space_delta, int64_t dspace_delta);
-uint64_t metaslab_class_get_alloc(metaslab_class_t *mc);
-uint64_t metaslab_class_get_space(metaslab_class_t *mc);
-uint64_t metaslab_class_get_dspace(metaslab_class_t *mc);
-uint64_t metaslab_class_get_deferred(metaslab_class_t *mc);
+void metaslab_class_space_update(metaslab_class_t *, int64_t, int64_t,
+    int64_t, int64_t);
+uint64_t metaslab_class_get_alloc(metaslab_class_t *);
+uint64_t metaslab_class_get_space(metaslab_class_t *);
+uint64_t metaslab_class_get_dspace(metaslab_class_t *);
+uint64_t metaslab_class_get_deferred(metaslab_class_t *);
 
-metaslab_group_t *metaslab_group_create(metaslab_class_t *mc, vdev_t *vd);
-void metaslab_group_destroy(metaslab_group_t *mg);
-void metaslab_group_activate(metaslab_group_t *mg);
-void metaslab_group_passivate(metaslab_group_t *mg);
+metaslab_group_t *metaslab_group_create(metaslab_class_t *, vdev_t *);
+void metaslab_group_destroy(metaslab_group_t *);
+void metaslab_group_activate(metaslab_group_t *);
+void metaslab_group_passivate(metaslab_group_t *);
+uint64_t metaslab_group_get_space(metaslab_group_t *);
+void metaslab_group_histogram_verify(metaslab_group_t *);
+uint64_t metaslab_group_fragmentation(metaslab_group_t *);
+void metaslab_group_histogram_remove(metaslab_group_t *, metaslab_t *);
 
 #ifdef	__cplusplus
 }