Improve instruction benchmarks (#9712)

* seal_input can be called multiple times

* Increase size of instruction benchmarks

* Remove randomness from instr_br* benchmarks

* cargo run --quiet --release --features=runtime-benchmarks --manifest-path=bin/node/cli/Cargo.toml -- benchmark --chain=dev --steps=50 --repeat=20 --pallet=pallet_contracts --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --output=./frame/contracts/src/weights.rs --template=./.maintain/frame-weight-template.hbs

Co-authored-by: Parity Bot <admin@parity.io>

substrate/Cargo.lock

@@ -6540,9 +6540,9 @@ dependencies = [
 
 [[package]]
 name = "pwasm-utils"
-version = "0.18.1"
+version = "0.18.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f0c1a2f10b47d446372a4f397c58b329aaea72b2daf9395a623a411cb8ccb54f"
+checksum = "880b3384fb00b8f6ecccd5d358b93bd2201900ae3daad213791d1864f6441f5c"
 dependencies = [
  "byteorder",
  "log 0.4.14",

substrate/frame/contracts/Cargo.toml

@@ -19,7 +19,7 @@ codec = { package = "parity-scale-codec", version = "2.2.0", default-features =
 	"max-encoded-len",
 ] }
 log = { version = "0.4", default-features = false }
-pwasm-utils = { version = "0.18", default-features = false }
+pwasm-utils = { version = "0.18.2", default-features = false }
 serde = { version = "1", optional = true, features = ["derive"] }
 smallvec = { version = "1", default-features = false, features = [
 	"const_generics",

substrate/frame/contracts/src/benchmarking/mod.rs

@@ -50,7 +50,7 @@ use sp_std::{convert::TryInto, default::Default, vec, vec::Vec};
 const API_BENCHMARK_BATCHES: u32 = 20;
 
 /// How many batches we do per Instruction benchmark.
-const INSTR_BENCHMARK_BATCHES: u32 = 1;
+const INSTR_BENCHMARK_BATCHES: u32 = 50;
 
 /// An instantiated and deployed contract.
 struct Contract<T: Config> {
@@ -444,11 +444,8 @@ benchmarks! {
 
 	}: call(origin, instance.addr, 0u32.into(), Weight::max_value(), vec![])
 
-	// We cannot call seal_input multiple times. Therefore our weight determination is not
-	// as precise as with other APIs. Because this function can only be called once per
-	// contract it cannot be used for Dos.
 	seal_input {
-		let r in 0 .. 1;
+		let r in 0 .. API_BENCHMARK_BATCHES;
 		let code = WasmModule::<T>::from(ModuleDefinition {
 			memory: Some(ImportedMemory::max::<T>()),
 			imported_functions: vec![ImportedFunction {
@@ -463,7 +460,7 @@ benchmarks! {
 					value: 0u32.to_le_bytes().to_vec(),
 				},
 			],
-			call_body: Some(body::repeated(r, &[
+			call_body: Some(body::repeated(r * API_BENCHMARK_BATCH_SIZE, &[
 				Instruction::I32Const(4), // ptr where to store output
 				Instruction::I32Const(0), // ptr to length
 				Instruction::Call(0),
@@ -492,11 +489,10 @@ benchmarks! {
 					value: buffer_size.to_le_bytes().to_vec(),
 				},
 			],
-			call_body: Some(body::plain(vec![
+			call_body: Some(body::repeated(API_BENCHMARK_BATCH_SIZE, &[
 				Instruction::I32Const(4), // ptr where to store output
 				Instruction::I32Const(0), // ptr to length
 				Instruction::Call(0),
-				Instruction::End,
 			])),
 			.. Default::default()
 		});
@@ -505,7 +501,9 @@ benchmarks! {
 		let origin = RawOrigin::Signed(instance.caller.clone());
 	}: call(origin, instance.addr, 0u32.into(), Weight::max_value(), data)
 
-	// The same argument as for `seal_input` is true here.
+	// We cannot call `seal_return` multiple times. Therefore our weight determination is not
+	// as precise as with other APIs. Because this function can only be called once per
+	// contract it cannot be used as an attack vector.
 	seal_return {
 		let r in 0 .. 1;
 		let code = WasmModule::<T>::from(ModuleDefinition {
@@ -551,7 +549,7 @@ benchmarks! {
 		let origin = RawOrigin::Signed(instance.caller.clone());
 	}: call(origin, instance.addr, 0u32.into(), Weight::max_value(), vec![])
 
-	// The same argument as for `seal_input` is true here.
+	// The same argument as for `seal_return` is true here.
 	seal_terminate {
 		let r in 0 .. 1;
 		let beneficiary = account::<T::AccountId>("beneficiary", 0, 0);
@@ -1509,6 +1507,7 @@ benchmarks! {
 	}
 
 	// w_br = w_bench - 2 * w_param
+	// Block instructions are not counted.
 	instr_br {
 		let r in 0 .. INSTR_BENCHMARK_BATCHES;
 		let mut sbox = Sandbox::from(&WasmModule::<T>::from(ModuleDefinition {
@@ -1533,9 +1532,8 @@ benchmarks! {
 		sbox.invoke();
 	}
 
-	// w_br_if = w_bench - 5 * w_param
-	// The two additional pushes + drop are only executed 50% of the time.
-	// Making it: 3 * w_param + (50% * 4 * w_param)
+	// w_br_if = w_bench - 3 * w_param
+	// Block instructions are not counted.
 	instr_br_if {
 		let r in 0 .. INSTR_BENCHMARK_BATCHES;
 		let mut sbox = Sandbox::from(&WasmModule::<T>::from(ModuleDefinition {
@@ -1543,7 +1541,7 @@ benchmarks! {
 				Regular(Instruction::Block(BlockType::NoResult)),
 				Regular(Instruction::Block(BlockType::NoResult)),
 				Regular(Instruction::Block(BlockType::NoResult)),
-				RandomI32(0, 2),
+				Regular(Instruction::I32Const(1)),
 				Regular(Instruction::BrIf(1)),
 				RandomI64Repeated(1),
 				Regular(Instruction::Drop),
@@ -1562,11 +1560,11 @@ benchmarks! {
 	}
 
 	// w_br_table = w_bench - 3 * w_param
-	// 1 * w_param + 0.5 * 2 * w_param + 0.25 * 4 * w_param
+	// Block instructions are not counted.
 	instr_br_table {
 		let r in 0 .. INSTR_BENCHMARK_BATCHES;
 		let table = Box::new(BrTableData {
-			table: Box::new([0, 1, 2]),
+			table: Box::new([1, 1, 1]),
 			default: 1,
 		});
 		let mut sbox = Sandbox::from(&WasmModule::<T>::from(ModuleDefinition {

substrate/frame/contracts/src/schedule.rs

@@ -36,7 +36,7 @@ pub const API_BENCHMARK_BATCH_SIZE: u32 = 100;
 
 /// How many instructions are executed in a single batch. The reasoning is the same
 /// as for `API_BENCHMARK_BATCH_SIZE`.
-pub const INSTR_BENCHMARK_BATCH_SIZE: u32 = 1_000;
+pub const INSTR_BENCHMARK_BATCH_SIZE: u32 = 100;
 
 /// Definition of the cost schedule and other parameterizations for the wasm vm.
 ///
@@ -495,7 +495,7 @@ impl<T: Config> Default for InstructionWeights<T> {
 			select: cost_instr!(instr_select, 4),
 			r#if: cost_instr!(instr_if, 3),
 			br: cost_instr!(instr_br, 2),
-			br_if: cost_instr!(instr_br_if, 5),
+			br_if: cost_instr!(instr_br_if, 3),
 			br_table: cost_instr!(instr_br_table, 3),
 			br_table_per_entry: cost_instr!(instr_br_table_per_entry, 0),
 			call: cost_instr!(instr_call, 2),
@@ -559,8 +559,8 @@ impl<T: Config> Default for HostFnWeights<T> {
 			now: cost_batched!(seal_now),
 			weight_to_fee: cost_batched!(seal_weight_to_fee),
 			gas: cost_batched!(seal_gas),
-			input: cost!(seal_input),
-			input_per_byte: cost_byte!(seal_input_per_kb),
+			input: cost_batched!(seal_input),
+			input_per_byte: cost_byte_batched!(seal_input_per_kb),
 			r#return: cost!(seal_return),
 			return_per_byte: cost_byte!(seal_return_per_kb),
 			terminate: cost!(seal_terminate),