short-term fix for para inherent weight overestimation (#5082)

closes #849

## Context

For the background on this and the long-term fix, see
#849 (comment).

## Changes

* The weigh files are renamed from `runtime_(parachains|common).*` to
`polkadot_runtime_(parachains|common).*`. The reason for it is the
renaming introduced in #4633. The new weight command and files are
generated now include `polkadot_` prefix.
* The WeightInfo for `paras_inherent` now includes `enter_empty` which
calculates the cost of processing an empty parachains inherent. This
cost is subtracted dynamically when calculating other weights (so the
other weights remain the same)

## Benefits

See
#849 (comment),
but TL;DR is that we are not blocked on weights for scaling the number
of validators and cores further.

Resolved questions:
- [x] why new benchmarks for westend are doing fewer db IOPS?
Is it due polkadot-sdk update (db IOPS diff)?
or the bench setup is no longer valid?

https://github.com/polkadot-fellows/runtimes/blob/7723274a2c5cbb10213379271094d5180716ca7d/relay/polkadot/src/weights/runtime_parachains_paras_inherent.rs#L131-L196
Answer: see background section of #5270 

TODOs:
- [x] Rerun benchmarks for Rococo and Westend
- [x] PRDoc

---------

Co-authored-by: command-bot <>

polkadot/runtime/parachains/src/builder.rs

@@ -221,9 +221,10 @@ impl<T: paras_inherent::Config> BenchBuilder<T> {
 			.expect("self.block_number is u32")
 	}
 
-	/// Maximum number of validators that may be part of a validator group.
+	/// Fallback for the maximum number of validators participating in parachains consensus (a.k.a.
+	/// active validators).
 	pub(crate) fn fallback_max_validators() -> u32 {
-		configuration::ActiveConfig::<T>::get().max_validators.unwrap_or(200)
+		configuration::ActiveConfig::<T>::get().max_validators.unwrap_or(1024)
 	}
 
 	/// Maximum number of validators participating in parachains consensus (a.k.a. active
@@ -285,8 +286,8 @@ impl<T: paras_inherent::Config> BenchBuilder<T> {
 
 	/// Get the minimum number of validity votes in order for a backed candidate to be included.
 	#[cfg(feature = "runtime-benchmarks")]
-	pub(crate) fn fallback_min_validity_votes() -> u32 {
-		(Self::fallback_max_validators() / 2) + 1
+	pub(crate) fn fallback_min_backing_votes() -> u32 {
+		2
 	}
 
 	fn mock_head_data() -> HeadData {
@@ -356,11 +357,11 @@ impl<T: paras_inherent::Config> BenchBuilder<T> {
 			availability_votes,
 			commitments,
 		);
-		inclusion::PendingAvailability::<T>::mutate(para_id, |maybe_andidates| {
-			if let Some(candidates) = maybe_andidates {
+		inclusion::PendingAvailability::<T>::mutate(para_id, |maybe_candidates| {
+			if let Some(candidates) = maybe_candidates {
 				candidates.push_back(candidate_availability);
 			} else {
-				*maybe_andidates =
+				*maybe_candidates =
 					Some([candidate_availability].into_iter().collect::<VecDeque<_>>());
 			}
 		});

polkadot/runtime/parachains/src/paras_inherent/benchmarking.rs

@@ -26,6 +26,20 @@ use polkadot_primitives::v7::GroupIndex;
 use crate::builder::BenchBuilder;
 
 benchmarks! {
+	enter_empty {
+		let scenario = BenchBuilder::<T>::new()
+			.build();
+
+		let mut benchmark = scenario.data.clone();
+
+		benchmark.bitfields.clear();
+		benchmark.backed_candidates.clear();
+		benchmark.disputes.clear();
+	}: enter(RawOrigin::None, benchmark)
+	verify {
+		// Assert that the block was not discarded
+		assert!(Included::<T>::get().is_some());
+	}
 	// Variant over `v`, the number of dispute statements in a dispute statement set. This gives the
 	// weight of a single dispute statement set.
 	enter_variable_disputes {
@@ -92,18 +106,8 @@ benchmarks! {
 	// Variant over `v`, the amount of validity votes for a backed candidate. This gives the weight
 	// of a single backed candidate.
 	enter_backed_candidates_variable {
-		// NOTE: the starting value must be over half of the max validators per group so the backed
-		// candidate is not rejected. Also, we cannot have more validity votes than validators in
-		// the group.
-
-		// Do not use this range for Rococo because it only has 1 validator per backing group,
-		// which causes issues when trying to create slopes with the benchmarking analysis. Instead
-		// use v = 1 for running Rococo benchmarks
-		let v in (BenchBuilder::<T>::fallback_min_validity_votes())
-			..(BenchBuilder::<T>::fallback_max_validators());
-
-		// Comment in for running rococo benchmarks
-		// let v = 1;
+		let v in (BenchBuilder::<T>::fallback_min_backing_votes())
+			..(BenchBuilder::<T>::fallback_max_validators_per_core());
 
 		let cores_with_backed: BTreeMap<_, _>
 			= vec![(0, v)] // The backed candidate will have `v` validity votes.
@@ -119,7 +123,6 @@ benchmarks! {
 		// There is 1 backed,
 		assert_eq!(benchmark.backed_candidates.len(), 1);
 		// with `v` validity votes.
-		// let votes = v as usize;
 		let votes = min(scheduler::Pallet::<T>::group_validators(GroupIndex::from(0)).unwrap().len(), v as usize);
 		assert_eq!(benchmark.backed_candidates.get(0).unwrap().validity_votes().len(), votes);
 
@@ -157,7 +160,7 @@ benchmarks! {
 		let v = crate::configuration::ActiveConfig::<T>::get().max_code_size;
 
 		let cores_with_backed: BTreeMap<_, _>
-			= vec![(0, BenchBuilder::<T>::fallback_min_validity_votes())]
+			= vec![(0, BenchBuilder::<T>::fallback_min_backing_votes())]
 				.into_iter()
 				.collect();
 
@@ -168,8 +171,10 @@ benchmarks! {
 
 		let mut benchmark = scenario.data.clone();
 
-		// let votes = BenchBuilder::<T>::fallback_min_validity_votes() as usize;
-		let votes = min(scheduler::Pallet::<T>::group_validators(GroupIndex::from(0)).unwrap().len(), BenchBuilder::<T>::fallback_min_validity_votes() as usize);
+		let votes = min(
+			scheduler::Pallet::<T>::group_validators(GroupIndex::from(0)).unwrap().len(),
+			BenchBuilder::<T>::fallback_min_backing_votes() as usize
+		);
 
 		// There is 1 backed
 		assert_eq!(benchmark.backed_candidates.len(), 1);

polkadot/runtime/parachains/src/paras_inherent/weights.rs

@@ -28,6 +28,8 @@ use polkadot_primitives::{
 use super::{BackedCandidate, Config, DisputeStatementSet, Weight};
 
 pub trait WeightInfo {
+	/// The weight of processing an empty parachain inherent.
+	fn enter_empty() -> Weight;
 	/// Variant over `v`, the count of dispute statements in a dispute statement set. This gives the
 	/// weight of a single dispute statement set.
 	fn enter_variable_disputes(v: u32) -> Weight;
@@ -45,6 +47,9 @@ pub struct TestWeightInfo;
 //  mock.
 #[cfg(not(feature = "runtime-benchmarks"))]
 impl WeightInfo for TestWeightInfo {
+	fn enter_empty() -> Weight {
+		Weight::zero()
+	}
 	fn enter_variable_disputes(v: u32) -> Weight {
 		// MAX Block Weight should fit 4 disputes
 		Weight::from_parts(80_000 * v as u64 + 80_000, 0)
@@ -66,6 +71,9 @@ impl WeightInfo for TestWeightInfo {
 // running as a test.
 #[cfg(feature = "runtime-benchmarks")]
 impl WeightInfo for TestWeightInfo {
+	fn enter_empty() -> Weight {
+		Weight::zero()
+	}
 	fn enter_variable_disputes(_v: u32) -> Weight {
 		Weight::zero()
 	}
@@ -123,7 +131,8 @@ where
 	set_proof_size_to_tx_size(
 		<<T as Config>::WeightInfo as WeightInfo>::enter_variable_disputes(
 			statement_set.as_ref().statements.len() as u32,
-		),
+		)
+		.saturating_sub(<<T as Config>::WeightInfo as WeightInfo>::enter_empty()),
 		statement_set,
 	)
 }
@@ -133,14 +142,16 @@ pub fn signed_bitfields_weight<T: Config>(
 ) -> Weight {
 	set_proof_size_to_tx_size(
 		<<T as Config>::WeightInfo as WeightInfo>::enter_bitfields()
+			.saturating_sub(<<T as Config>::WeightInfo as WeightInfo>::enter_empty())
 			.saturating_mul(bitfields.len() as u64),
 		bitfields,
 	)
 }
 
 pub fn signed_bitfield_weight<T: Config>(bitfield: &UncheckedSignedAvailabilityBitfield) -> Weight {
 	set_proof_size_to_tx_size(
-		<<T as Config>::WeightInfo as WeightInfo>::enter_bitfields(),
+		<<T as Config>::WeightInfo as WeightInfo>::enter_bitfields()
+			.saturating_sub(<<T as Config>::WeightInfo as WeightInfo>::enter_empty()),
 		bitfield,
 	)
 }
@@ -155,7 +166,8 @@ pub fn backed_candidate_weight<T: frame_system::Config + Config>(
 			<<T as Config>::WeightInfo as WeightInfo>::enter_backed_candidates_variable(
 				candidate.validity_votes().len() as u32,
 			)
-		},
+		}
+		.saturating_sub(<<T as Config>::WeightInfo as WeightInfo>::enter_empty()),
 		candidate,
 	)
 }

polkadot/runtime/rococo/src/impls.rs

@@ -90,7 +90,7 @@ where
 	fn on_reap_identity(who: &AccountId, fields: u32, subs: u32) -> DispatchResult {
 		use crate::{
 			impls::IdentityMigratorCalls::PokeDeposit,
-			weights::runtime_common_identity_migrator::WeightInfo as MigratorWeights,
+			weights::polkadot_runtime_common_identity_migrator::WeightInfo as MigratorWeights,
 		};
 
 		let total_to_send = Self::calculate_remote_deposit(fields, subs);

polkadot/runtime/rococo/src/lib.rs

@@ -674,7 +674,7 @@ impl claims::Config for Runtime {
 	type VestingSchedule = Vesting;
 	type Prefix = Prefix;
 	type MoveClaimOrigin = EnsureRoot<AccountId>;
-	type WeightInfo = weights::runtime_common_claims::WeightInfo<Runtime>;
+	type WeightInfo = weights::polkadot_runtime_common_claims::WeightInfo<Runtime>;
 }
 
 parameter_types! {
@@ -940,7 +940,7 @@ impl pallet_proxy::Config for Runtime {
 impl parachains_origin::Config for Runtime {}
 
 impl parachains_configuration::Config for Runtime {
-	type WeightInfo = weights::runtime_parachains_configuration::WeightInfo<Runtime>;
+	type WeightInfo = weights::polkadot_runtime_parachains_configuration::WeightInfo<Runtime>;
 }
 
 impl parachains_shared::Config for Runtime {
@@ -963,7 +963,7 @@ impl parachains_inclusion::Config for Runtime {
 	type DisputesHandler = ParasDisputes;
 	type RewardValidators = RewardValidators;
 	type MessageQueue = MessageQueue;
-	type WeightInfo = weights::runtime_parachains_inclusion::WeightInfo<Runtime>;
+	type WeightInfo = weights::polkadot_runtime_parachains_inclusion::WeightInfo<Runtime>;
 }
 
 parameter_types! {
@@ -972,7 +972,7 @@ parameter_types! {
 
 impl parachains_paras::Config for Runtime {
 	type RuntimeEvent = RuntimeEvent;
-	type WeightInfo = weights::runtime_parachains_paras::WeightInfo<Runtime>;
+	type WeightInfo = weights::polkadot_runtime_parachains_paras::WeightInfo<Runtime>;
 	type UnsignedPriority = ParasUnsignedPriority;
 	type QueueFootprinter = ParaInclusion;
 	type NextSessionRotation = Babe;
@@ -1046,11 +1046,11 @@ impl parachains_hrmp::Config for Runtime {
 		HrmpChannelSizeAndCapacityWithSystemRatio,
 	>;
 	type VersionWrapper = crate::XcmPallet;
-	type WeightInfo = weights::runtime_parachains_hrmp::WeightInfo<Runtime>;
+	type WeightInfo = weights::polkadot_runtime_parachains_hrmp::WeightInfo<Runtime>;
 }
 
 impl parachains_paras_inherent::Config for Runtime {
-	type WeightInfo = weights::runtime_parachains_paras_inherent::WeightInfo<Runtime>;
+	type WeightInfo = weights::polkadot_runtime_parachains_paras_inherent::WeightInfo<Runtime>;
 }
 
 impl parachains_scheduler::Config for Runtime {
@@ -1079,7 +1079,7 @@ impl coretime::Config for Runtime {
 	type Currency = Balances;
 	type BrokerId = BrokerId;
 	type BrokerPotLocation = BrokerPot;
-	type WeightInfo = weights::runtime_parachains_coretime::WeightInfo<Runtime>;
+	type WeightInfo = weights::polkadot_runtime_parachains_coretime::WeightInfo<Runtime>;
 	type SendXcm = crate::xcm_config::XcmRouter;
 	type AssetTransactor = crate::xcm_config::LocalAssetTransactor;
 	type AccountToLocation = xcm_builder::AliasesIntoAccountId32<
@@ -1100,7 +1100,7 @@ impl parachains_on_demand::Config for Runtime {
 	type RuntimeEvent = RuntimeEvent;
 	type Currency = Balances;
 	type TrafficDefaultValue = OnDemandTrafficDefaultValue;
-	type WeightInfo = weights::runtime_parachains_on_demand::WeightInfo<Runtime>;
+	type WeightInfo = weights::polkadot_runtime_parachains_on_demand::WeightInfo<Runtime>;
 	type MaxHistoricalRevenue = MaxHistoricalRevenue;
 	type PalletId = OnDemandPalletId;
 }
@@ -1110,15 +1110,15 @@ impl parachains_assigner_coretime::Config for Runtime {}
 impl parachains_initializer::Config for Runtime {
 	type Randomness = pallet_babe::RandomnessFromOneEpochAgo<Runtime>;
 	type ForceOrigin = EnsureRoot<AccountId>;
-	type WeightInfo = weights::runtime_parachains_initializer::WeightInfo<Runtime>;
+	type WeightInfo = weights::polkadot_runtime_parachains_initializer::WeightInfo<Runtime>;
 	type CoretimeOnNewSession = Coretime;
 }
 
 impl parachains_disputes::Config for Runtime {
 	type RuntimeEvent = RuntimeEvent;
 	type RewardValidators = ();
 	type SlashingHandler = parachains_slashing::SlashValidatorsForDisputes<ParasSlashing>;
-	type WeightInfo = weights::runtime_parachains_disputes::WeightInfo<Runtime>;
+	type WeightInfo = weights::polkadot_runtime_parachains_disputes::WeightInfo<Runtime>;
 }
 
 impl parachains_slashing::Config for Runtime {
@@ -1149,7 +1149,7 @@ impl paras_registrar::Config for Runtime {
 	type OnSwap = (Crowdloan, Slots, SwapLeases);
 	type ParaDeposit = ParaDeposit;
 	type DataDepositPerByte = DataDepositPerByte;
-	type WeightInfo = weights::runtime_common_paras_registrar::WeightInfo<Runtime>;
+	type WeightInfo = weights::polkadot_runtime_common_paras_registrar::WeightInfo<Runtime>;
 }
 
 parameter_types! {
@@ -1163,7 +1163,7 @@ impl slots::Config for Runtime {
 	type LeasePeriod = LeasePeriod;
 	type LeaseOffset = ();
 	type ForceOrigin = EitherOf<EnsureRoot<Self::AccountId>, LeaseAdmin>;
-	type WeightInfo = weights::runtime_common_slots::WeightInfo<Runtime>;
+	type WeightInfo = weights::polkadot_runtime_common_slots::WeightInfo<Runtime>;
 }
 
 parameter_types! {
@@ -1184,7 +1184,7 @@ impl crowdloan::Config for Runtime {
 	type Registrar = Registrar;
 	type Auctioneer = Auctions;
 	type MaxMemoLength = MaxMemoLength;
-	type WeightInfo = weights::runtime_common_crowdloan::WeightInfo<Runtime>;
+	type WeightInfo = weights::polkadot_runtime_common_crowdloan::WeightInfo<Runtime>;
 }
 
 parameter_types! {
@@ -1203,14 +1203,14 @@ impl auctions::Config for Runtime {
 	type SampleLength = SampleLength;
 	type Randomness = pallet_babe::RandomnessFromOneEpochAgo<Runtime>;
 	type InitiateOrigin = EitherOf<EnsureRoot<Self::AccountId>, AuctionAdmin>;
-	type WeightInfo = weights::runtime_common_auctions::WeightInfo<Runtime>;
+	type WeightInfo = weights::polkadot_runtime_common_auctions::WeightInfo<Runtime>;
 }
 
 impl identity_migrator::Config for Runtime {
 	type RuntimeEvent = RuntimeEvent;
 	type Reaper = EnsureSigned<AccountId>;
 	type ReapIdentityHandler = ToParachainIdentityReaper<Runtime, Self::AccountId>;
-	type WeightInfo = weights::runtime_common_identity_migrator::WeightInfo<Runtime>;
+	type WeightInfo = weights::polkadot_runtime_common_identity_migrator::WeightInfo<Runtime>;
 }
 
 type NisCounterpartInstance = pallet_balances::Instance2;
@@ -1353,7 +1353,7 @@ impl assigned_slots::Config for Runtime {
 	type PermanentSlotLeasePeriodLength = PermanentSlotLeasePeriodLength;
 	type TemporarySlotLeasePeriodLength = TemporarySlotLeasePeriodLength;
 	type MaxTemporarySlotPerLeasePeriod = MaxTemporarySlotPerLeasePeriod;
-	type WeightInfo = weights::runtime_common_assigned_slots::WeightInfo<Runtime>;
+	type WeightInfo = weights::polkadot_runtime_common_assigned_slots::WeightInfo<Runtime>;
 }
 
 impl validator_manager::Config for Runtime {

polkadot/runtime/rococo/src/weights/mod.rs

@@ -44,20 +44,20 @@ pub mod pallet_utility;
 pub mod pallet_vesting;
 pub mod pallet_whitelist;
 pub mod pallet_xcm;
-pub mod runtime_common_assigned_slots;
-pub mod runtime_common_auctions;
-pub mod runtime_common_claims;
-pub mod runtime_common_crowdloan;
-pub mod runtime_common_identity_migrator;
-pub mod runtime_common_paras_registrar;
-pub mod runtime_common_slots;
-pub mod runtime_parachains_configuration;
-pub mod runtime_parachains_coretime;
-pub mod runtime_parachains_disputes;
-pub mod runtime_parachains_hrmp;
-pub mod runtime_parachains_inclusion;
-pub mod runtime_parachains_initializer;
-pub mod runtime_parachains_on_demand;
-pub mod runtime_parachains_paras;
-pub mod runtime_parachains_paras_inherent;
+pub mod polkadot_runtime_common_assigned_slots;
+pub mod polkadot_runtime_common_auctions;
+pub mod polkadot_runtime_common_claims;
+pub mod polkadot_runtime_common_crowdloan;
+pub mod polkadot_runtime_common_identity_migrator;
+pub mod polkadot_runtime_common_paras_registrar;
+pub mod polkadot_runtime_common_slots;
+pub mod polkadot_runtime_parachains_configuration;
+pub mod polkadot_runtime_parachains_coretime;
+pub mod polkadot_runtime_parachains_disputes;
+pub mod polkadot_runtime_parachains_hrmp;
+pub mod polkadot_runtime_parachains_inclusion;
+pub mod polkadot_runtime_parachains_initializer;
+pub mod polkadot_runtime_parachains_on_demand;
+pub mod polkadot_runtime_parachains_paras;
+pub mod polkadot_runtime_parachains_paras_inherent;
 pub mod xcm;