weights-benchmarking.md

Weights benchmarking

What is the reference machine?

For now (09/2022), it's a Raspberry Pi 4 Model B - 4GB with an SSD connected via USB3.

To cross-compile the benchmarks binary for armv7:

./scripts/cross-build-arm.sh --features runtime-benchmarks

The cross compiled binary is generated here: target/armv7-unknown-linux-gnueabihf/release/duniter

How to benchmarks weights of a Call/Hook/Pallet

1. Create the benchmarking tests, see commit 31057e37 for a complete real example.
2. Run the benchmark test on your local machine: cargo test -p <pallet> --features runtime-benchmarks
3. If the benchmark tests compiles and pass, compile the binary with benchmarks on your local machine: cargo build --release --features runtime-benchmarks
4. Run the benchmarks on your local machine (to test if it work with a real runtime). The command is: duniter benchmark pallet --chain=CURRENCY-dev --steps=50 --repeat=20 --pallet=pallet_universal_dividend --extrinsic=* --execution=wasm --wasm-execution=compiled --heap-pages=4096 --header=./file_header.txt --output=.
5. If it worked, use the generated file content to create or update the WeightInfo trait and the () dummy implementation. Then use the WeightInfo tarit in the real code of the pallet. See 79e0fd4b for a complete real example.
6. Redo steps 3. and 4. on the reference machine.
7. Put the generated file on runtime/common/src/weights and use it in the runtimes configuration. See cee7c3b2 for a complete real example.

Note 1: You must replace CURRENCY by the currency type, or for ĞDev use directly --chain=dev.

Note 2: If the reference machine does not support wasmtime, you should replace --wasm-execution=compiled by --wasm-execution=interpreted-i-know-what-i-do.

Generate base block benchmarking

1. Build binary for reference machine and copy it on reference machine.
2. Run base block benchmarks command:

./duniter benchmark overhead --chain=gdev --execution=wasm --wasm-execution=interpreted-i-know-what-i-do --weight-path=. --warmup=10 --repeat=100

3. Copy the generated file block_weights.rs in the codebase in folder runtime/common/src/weights/.
4. Commit changes and open an MR.

Generate storage benchmarking

1. Build binary for reference machine and copy it on reference machine.
2. Copy a DB on reference machine (on ssd), example: scp -r -P 37015 tmp/t1 pi@192.168.1.188:/mnt/ssd1/duniter-v2s/
3. Run storage benchmarks command, example:

./duniter benchmark storage -d=/mnt/ssd1/duniter-v2s/t1 --chain=gdev --mul=2 --weight-path=. --state-version=1

4. Copy the generated file paritydb_weights.rs in the codebase in folder runtime/common/src/weights/.
5. Commit changes and open an MR.