Storage benchmarking (#10897)

* WIP Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * WIP: DB benchmarking Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * WIP Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * WIP Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Simplify code Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Remove old files Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Remove old files Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Minimize changes Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Add license Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Remove dependencies Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Extend template Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Linter Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Linter Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Beauty fixes Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Remove default Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Add feature Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Remove seed Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * CI wakeup Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Fmt Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Review fixes Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Adding doc Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Adding doc Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Improve template Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Do not expose columns Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Fix ColumnId Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Nicer template prints Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Cleanup Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Fix json path Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Simplify `bench_write` logic Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io> * Invert tx before the second commit Signed-off-by: Oliver Tale-Yazdi <oliver.tale-yazdi@parity.io>
2026-04-26 15:47:58 +00:00 · 2022-02-25 20:30:57 +01:00
parent d551fe6613
commit 4c984500a7
19 changed files with 917 additions and 11 deletions
@@ -16,11 +16,14 @@
 // limitations under the License.

 mod command;
+mod storage;
 mod writer;

 use sc_cli::{ExecutionStrategy, WasmExecutionMethod};
 use std::{fmt::Debug, path::PathBuf};

+pub use storage::StorageCmd;
+
 // Add a more relaxed parsing for pallet names by allowing pallet directory names with `-` to be
 // used like crate names with `_`
 fn parse_pallet_name(pallet: &str) -> String {
@@ -0,0 +1,171 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use sc_cli::{CliConfiguration, DatabaseParams, PruningParams, Result, SharedParams};
+use sc_client_api::{Backend as ClientBackend, StorageProvider, UsageProvider};
+use sc_client_db::DbHash;
+use sc_service::Configuration;
+use sp_blockchain::HeaderBackend;
+use sp_database::{ColumnId, Database};
+use sp_runtime::traits::{Block as BlockT, HashFor};
+use sp_state_machine::Storage;
+use sp_storage::StateVersion;
+
+use clap::{Args, Parser};
+use log::info;
+use rand::prelude::*;
+use serde::Serialize;
+use std::{fmt::Debug, sync::Arc};
+
+use super::{record::StatSelect, template::TemplateData};
+
+/// Benchmark the storage of a Substrate node with a live chain snapshot.
+#[derive(Debug, Parser)]
+pub struct StorageCmd {
+	#[allow(missing_docs)]
+	#[clap(flatten)]
+	pub shared_params: SharedParams,
+
+	#[allow(missing_docs)]
+	#[clap(flatten)]
+	pub database_params: DatabaseParams,
+
+	#[allow(missing_docs)]
+	#[clap(flatten)]
+	pub pruning_params: PruningParams,
+
+	#[allow(missing_docs)]
+	#[clap(flatten)]
+	pub params: StorageParams,
+}
+
+/// Parameters for modifying the benchmark behaviour and the post processing of the results.
+#[derive(Debug, Default, Serialize, Clone, PartialEq, Args)]
+pub struct StorageParams {
+	/// Path to write the *weight* file to. Can be a file or directory.
+	/// For substrate this should be `frame/support/src/weights`.
+	#[clap(long, default_value = ".")]
+	pub weight_path: String,
+
+	/// Select a specific metric to calculate the final weight output.
+	#[clap(long = "metric", default_value = "average")]
+	pub weight_metric: StatSelect,
+
+	/// Multiply the resulting weight with the given factor. Must be positive.
+	/// Is calculated before `weight_add`.
+	#[clap(long = "mul", default_value = "1")]
+	pub weight_mul: f64,
+
+	/// Add the given offset to the resulting weight.
+	/// Is calculated after `weight_mul`.
+	#[clap(long = "add", default_value = "0")]
+	pub weight_add: u64,
+
+	/// Skip the `read` benchmark.
+	#[clap(long)]
+	pub skip_read: bool,
+
+	/// Skip the `write` benchmark.
+	#[clap(long)]
+	pub skip_write: bool,
+
+	/// Rounds of warmups before measuring.
+	/// Only supported for `read` benchmarks.
+	#[clap(long, default_value = "1")]
+	pub warmups: u32,
+
+	/// The `StateVersion` to use. Substrate `--dev` should use `V1` and Polkadot `V0`.
+	/// Selecting the wrong version can corrupt the DB.
+	#[clap(long, possible_values = ["0", "1"])]
+	pub state_version: u8,
+
+	/// State cache size.
+	#[clap(long, default_value = "0")]
+	pub state_cache_size: usize,
+}
+
+impl StorageCmd {
+	/// Calls into the Read and Write benchmarking functions.
+	/// Processes the output and writes it into files and stdout.
+	pub async fn run<Block, BA, C>(
+		&self,
+		cfg: Configuration,
+		client: Arc<C>,
+		db: (Arc<dyn Database<DbHash>>, ColumnId),
+		storage: Arc<dyn Storage<HashFor<Block>>>,
+	) -> Result<()>
+	where
+		BA: ClientBackend<Block>,
+		Block: BlockT<Hash = DbHash>,
+		C: UsageProvider<Block> + StorageProvider<Block, BA> + HeaderBackend<Block>,
+	{
+		let mut template = TemplateData::new(&cfg, &self.params);
+
+		if !self.params.skip_read {
+			let record = self.bench_read(client.clone())?;
+			record.save_json(&cfg, "read")?;
+			let stats = record.calculate_stats()?;
+			info!("Time summary [ns]:\n{:?}\nValue size summary:\n{:?}", stats.0, stats.1);
+			template.set_stats(Some(stats), None)?;
+		}
+
+		if !self.params.skip_write {
+			let record = self.bench_write(client, db, storage)?;
+			record.save_json(&cfg, "write")?;
+			let stats = record.calculate_stats()?;
+			info!("Time summary [ns]:\n{:?}\nValue size summary:\n{:?}", stats.0, stats.1);
+			template.set_stats(None, Some(stats))?;
+		}
+
+		template.write(&self.params.weight_path)
+	}
+
+	/// Returns the specified state version.
+	pub(crate) fn state_version(&self) -> StateVersion {
+		match self.params.state_version {
+			0 => StateVersion::V0,
+			1 => StateVersion::V1,
+			_ => unreachable!("Clap set to only allow 0 and 1"),
+		}
+	}
+
+	/// Creates an rng from a random seed.
+	pub(crate) fn setup_rng() -> impl rand::Rng {
+		let seed = rand::thread_rng().gen::<u64>();
+		info!("Using seed {}", seed);
+		StdRng::seed_from_u64(seed)
+	}
+}
+
+// Boilerplate
+impl CliConfiguration for StorageCmd {
+	fn shared_params(&self) -> &SharedParams {
+		&self.shared_params
+	}
+
+	fn database_params(&self) -> Option<&DatabaseParams> {
+		Some(&self.database_params)
+	}
+
+	fn pruning_params(&self) -> Option<&PruningParams> {
+		Some(&self.pruning_params)
+	}
+
+	fn state_cache_size(&self) -> Result<usize> {
+		Ok(self.params.state_cache_size)
+	}
+}
@@ -0,0 +1,24 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+pub mod cmd;
+pub mod read;
+pub mod record;
+pub mod template;
+pub mod write;
+
+pub use cmd::StorageCmd;
@@ -0,0 +1,76 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use sc_cli::Result;
+use sc_client_api::{Backend as ClientBackend, StorageProvider, UsageProvider};
+use sp_core::storage::StorageKey;
+use sp_runtime::{
+	generic::BlockId,
+	traits::{Block as BlockT, Header as HeaderT},
+};
+
+use log::info;
+use rand::prelude::*;
+use std::{fmt::Debug, sync::Arc, time::Instant};
+
+use super::{cmd::StorageCmd, record::BenchRecord};
+
+impl StorageCmd {
+	/// Benchmarks the time it takes to read a single Storage item.
+	/// Uses the latest state that is available for the given client.
+	pub(crate) fn bench_read<B, BA, C>(&self, client: Arc<C>) -> Result<BenchRecord>
+	where
+		C: UsageProvider<B> + StorageProvider<B, BA>,
+		B: BlockT + Debug,
+		BA: ClientBackend<B>,
+		<<B as BlockT>::Header as HeaderT>::Number: From<u32>,
+	{
+		let mut record = BenchRecord::default();
+		let block = BlockId::Number(client.usage_info().chain.best_number);
+
+		info!("Preparing keys from block {}", block);
+		// Load all keys and randomly shuffle them.
+		let empty_prefix = StorageKey(Vec::new());
+		let mut keys = client.storage_keys(&block, &empty_prefix)?;
+		let mut rng = Self::setup_rng();
+		keys.shuffle(&mut rng);
+
+		// Run some rounds of the benchmark as warmup.
+		for i in 0..self.params.warmups {
+			info!("Warmup round {}/{}", i + 1, self.params.warmups);
+			for key in keys.clone() {
+				let _ = client
+					.storage(&block, &key)
+					.expect("Checked above to exist")
+					.ok_or("Value unexpectedly empty")?;
+			}
+		}
+
+		// Interesting part here:
+		// Read all the keys in the database and measure the time it takes to access each.
+		info!("Reading {} keys", keys.len());
+		for key in keys.clone() {
+			let start = Instant::now();
+			let v = client
+				.storage(&block, &key)
+				.expect("Checked above to exist")
+				.ok_or("Value unexpectedly empty")?;
+			record.append(v.0.len(), start.elapsed())?;
+		}
+		Ok(record)
+	}
+}
@@ -0,0 +1,191 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Calculates statistics and fills out the `weight.hbs` template.
+
+use sc_cli::Result;
+use sc_service::Configuration;
+
+use log::info;
+use serde::Serialize;
+use std::{fmt, fs, result, str::FromStr, time::Duration};
+
+/// Raw output of a Storage benchmark.
+#[derive(Debug, Default, Clone, Serialize)]
+pub(crate) struct BenchRecord {
+	/// Multi-Map of value sizes and the time that it took to access them.
+	ns_per_size: Vec<(u64, u64)>,
+}
+
+/// Various statistics that help to gauge the quality of the produced weights.
+/// Will be written to the weight file and printed to console.
+#[derive(Serialize, Default, Clone)]
+pub(crate) struct Stats {
+	/// Sum of all values.
+	sum: u64,
+	/// Minimal observed value.
+	min: u64,
+	/// Maximal observed value.
+	max: u64,
+
+	/// Average of all values.
+	avg: u64,
+	/// Median of all values.
+	median: u64,
+	/// Standard derivation of all values.
+	stddev: f64,
+
+	/// 99th percentile. At least 99% of all values are below this threshold.
+	p99: u64,
+	/// 95th percentile. At least 95% of all values are below this threshold.
+	p95: u64,
+	/// 75th percentile. At least 75% of all values are below this threshold.
+	p75: u64,
+}
+
+/// Selects a specific field from a [`Stats`] object.
+/// Not all fields are available.
+#[derive(Debug, Clone, Copy, Serialize, PartialEq)]
+pub enum StatSelect {
+	/// Select the maximum.
+	Maximum,
+	/// Select the average.
+	Average,
+	/// Select the median.
+	Median,
+	/// Select the 99th percentile.
+	P99Percentile,
+	/// Select the 95th percentile.
+	P95Percentile,
+	/// Select the 75th percentile.
+	P75Percentile,
+}
+
+impl BenchRecord {
+	/// Appends a new record. Uses safe casts.
+	pub fn append(&mut self, size: usize, d: Duration) -> Result<()> {
+		let size: u64 = size.try_into().map_err(|e| format!("Size overflow u64: {}", e))?;
+		let ns: u64 = d
+			.as_nanos()
+			.try_into()
+			.map_err(|e| format!("Nanoseconds overflow u64: {}", e))?;
+		self.ns_per_size.push((size, ns));
+		Ok(())
+	}
+
+	/// Returns the statistics for *time* and *value size*.
+	pub(crate) fn calculate_stats(self) -> Result<(Stats, Stats)> {
+		let (size, time): (Vec<_>, Vec<_>) = self.ns_per_size.into_iter().unzip();
+		let size = Stats::new(&size)?;
+		let time = Stats::new(&time)?;
+		Ok((time, size)) // The swap of time/size here is intentional.
+	}
+
+	/// Saves the raw results in a json file in the current directory.
+	/// Prefixes it with the DB name and suffixed with `path_suffix`.
+	pub fn save_json(&self, cfg: &Configuration, path_suffix: &str) -> Result<()> {
+		let path = format!("{}_{}.json", cfg.database, path_suffix).to_lowercase();
+		let json = serde_json::to_string_pretty(&self)
+			.map_err(|e| format!("Serializing as JSON: {:?}", e))?;
+		fs::write(&path, json)?;
+		info!("Raw data written to {:?}", fs::canonicalize(&path)?);
+		Ok(())
+	}
+}
+
+impl Stats {
+	/// Calculates statistics and returns them.
+	pub fn new(xs: &Vec<u64>) -> Result<Self> {
+		if xs.is_empty() {
+			return Err("Empty input is invalid".into())
+		}
+		let (avg, stddev) = Self::avg_and_stddev(&xs);
+
+		Ok(Self {
+			sum: xs.iter().sum(),
+			min: *xs.iter().min().expect("Checked for non-empty above"),
+			max: *xs.iter().max().expect("Checked for non-empty above"),
+
+			avg: avg as u64,
+			median: Self::percentile(xs.clone(), 0.50),
+			stddev: (stddev * 100.0).round() / 100.0, // round to 1/100
+
+			p99: Self::percentile(xs.clone(), 0.99),
+			p95: Self::percentile(xs.clone(), 0.95),
+			p75: Self::percentile(xs.clone(), 0.75),
+		})
+	}
+
+	/// Returns the selected stat.
+	pub(crate) fn select(&self, s: StatSelect) -> u64 {
+		match s {
+			StatSelect::Maximum => self.max,
+			StatSelect::Average => self.avg,
+			StatSelect::Median => self.median,
+			StatSelect::P99Percentile => self.p99,
+			StatSelect::P95Percentile => self.p95,
+			StatSelect::P75Percentile => self.p75,
+		}
+	}
+
+	/// Returns the *average* and the *standard derivation*.
+	fn avg_and_stddev(xs: &Vec<u64>) -> (f64, f64) {
+		let avg = xs.iter().map(|x| *x as f64).sum::<f64>() / xs.len() as f64;
+		let variance = xs.iter().map(|x| (*x as f64 - avg).powi(2)).sum::<f64>() / xs.len() as f64;
+		(avg, variance.sqrt())
+	}
+
+	/// Returns the specified percentile for the given data.
+	/// This is best effort since it ignores the interpolation case.
+	fn percentile(mut xs: Vec<u64>, p: f64) -> u64 {
+		xs.sort();
+		let index = (xs.len() as f64 * p).ceil() as usize;
+		xs[index]
+	}
+}
+
+impl fmt::Debug for Stats {
+	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+		write!(f, "Total: {}\n", self.sum)?;
+		write!(f, "Min: {}, Max: {}\n", self.min, self.max)?;
+		write!(f, "Average: {}, Median: {}, Stddev: {}\n", self.avg, self.median, self.stddev)?;
+		write!(f, "Percentiles 99th, 95th, 75th: {}, {}, {}", self.p99, self.p95, self.p75)
+	}
+}
+
+impl Default for StatSelect {
+	/// Returns the `Average` selector.
+	fn default() -> Self {
+		Self::Average
+	}
+}
+
+impl FromStr for StatSelect {
+	type Err = &'static str;
+
+	fn from_str(day: &str) -> result::Result<Self, Self::Err> {
+		match day.to_lowercase().as_str() {
+			"max" => Ok(Self::Maximum),
+			"average" => Ok(Self::Average),
+			"median" => Ok(Self::Median),
+			"p99" => Ok(Self::P99Percentile),
+			"p95" => Ok(Self::P95Percentile),
+			"p75" => Ok(Self::P75Percentile),
+			_ => Err("String was not a StatSelect"),
+		}
+	}
+}
@@ -0,0 +1,126 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use sc_cli::Result;
+use sc_service::Configuration;
+
+use log::info;
+use serde::Serialize;
+use std::{env, fs, path::PathBuf};
+
+use super::{cmd::StorageParams, record::Stats};
+
+static VERSION: &'static str = env!("CARGO_PKG_VERSION");
+static TEMPLATE: &str = include_str!("./weights.hbs");
+
+/// Data consumed by Handlebar to fill out the `weights.hbs` template.
+#[derive(Serialize, Default, Debug, Clone)]
+pub(crate) struct TemplateData {
+	/// Name of the database used.
+	db_name: String,
+	/// Name of the runtime. Taken from the chain spec.
+	runtime_name: String,
+	/// Version of the benchmarking CLI used.
+	version: String,
+	/// Date that the template was filled out.
+	date: String,
+	/// Command line arguments that were passed to the CLI.
+	args: Vec<String>,
+	/// Storage params of the executed command.
+	params: StorageParams,
+	/// The weight for one `read`.
+	read_weight: u64,
+	/// The weight for one `write`.
+	write_weight: u64,
+	/// Stats about a `read` benchmark. Contains *time* and *value size* stats.
+	/// The *value size* stats are currently not used in the template.
+	read: Option<(Stats, Stats)>,
+	/// Stats about a `write` benchmark. Contains *time* and *value size* stats.
+	/// The *value size* stats are currently not used in the template.
+	write: Option<(Stats, Stats)>,
+}
+
+impl TemplateData {
+	/// Returns a new [`Self`] from the given configuration.
+	pub fn new(cfg: &Configuration, params: &StorageParams) -> Self {
+		TemplateData {
+			db_name: format!("{}", cfg.database),
+			runtime_name: cfg.chain_spec.name().into(),
+			version: VERSION.into(),
+			date: chrono::Utc::now().format("%Y-%m-%d (Y/M/D)").to_string(),
+			args: env::args().collect::<Vec<String>>(),
+			params: params.clone(),
+			..Default::default()
+		}
+	}
+
+	/// Sets the stats and calculates the final weights.
+	pub fn set_stats(
+		&mut self,
+		read: Option<(Stats, Stats)>,
+		write: Option<(Stats, Stats)>,
+	) -> Result<()> {
+		if let Some(read) = read {
+			self.read_weight = calc_weight(&read.0, &self.params)?;
+			self.read = Some(read);
+		}
+		if let Some(write) = write {
+			self.write_weight = calc_weight(&write.0, &self.params)?;
+			self.write = Some(write);
+		}
+		Ok(())
+	}
+
+	/// Filles out the `weights.hbs` HBS template with its own data.
+	/// Writes the result to `path` which can be a directory or file.
+	pub fn write(&self, path: &str) -> Result<()> {
+		let mut handlebars = handlebars::Handlebars::new();
+		// Format large integers with underscore.
+		handlebars.register_helper("underscore", Box::new(crate::writer::UnderscoreHelper));
+		// Don't HTML escape any characters.
+		handlebars.register_escape_fn(|s| -> String { s.to_string() });
+
+		let out_path = self.build_path(path);
+		let mut fd = fs::File::create(&out_path)?;
+		info!("Writing weights to {:?}", fs::canonicalize(&out_path)?);
+		handlebars
+			.render_template_to_write(&TEMPLATE, &self, &mut fd)
+			.map_err(|e| format!("HBS template write: {:?}", e).into())
+	}
+
+	/// Builds a path for the weight file.
+	fn build_path(&self, weight_out: &str) -> PathBuf {
+		let mut path = PathBuf::from(weight_out);
+		if path.is_dir() {
+			path.push(format!("{}_weights.rs", self.db_name.to_lowercase()));
+			path.set_extension("rs");
+		}
+		path
+	}
+}
+
+/// Calculates the final weight by multiplying the selected metric with
+/// `mul` and adding `add`.
+/// Does not use safe casts and can overflow.
+fn calc_weight(stat: &Stats, params: &StorageParams) -> Result<u64> {
+	if params.weight_mul.is_sign_negative() || !params.weight_mul.is_normal() {
+		return Err("invalid floating number for `weight_mul`".into())
+	}
+	let s = stat.select(params.weight_metric) as f64;
+	let w = s.mul_add(params.weight_mul, params.weight_add as f64).ceil();
+	Ok(w as u64) // No safe cast here since there is no `From<f64>` for `u64`.
+}
@@ -0,0 +1,107 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! THIS FILE WAS AUTO-GENERATED USING THE SUBSTRATE BENCHMARK CLI VERSION {{version}}
+//! DATE: {{date}}
+//!
+//! DATABASE: `{{db_name}}`, RUNTIME: `{{runtime_name}}`
+//! SKIP-WRITE: `{{params.skip_write}}`, SKIP-READ: `{{params.skip_read}}`, WARMUPS: `{{params.warmups}}`
+//! STATE-VERSION: `V{{params.state_version}}`, STATE-CACHE-SIZE: `{{params.state_cache_size}}`
+//! WEIGHT-PATH: `{{params.weight_path}}`
+//! METRIC: `{{params.weight_metric}}`, WEIGHT-MUL: `{{params.weight_mul}}`, WEIGHT-ADD: `{{params.weight_add}}`
+
+// Executed Command:
+{{#each args as |arg|}}
+//   {{arg}}
+{{/each}}
+
+/// Storage DB weights for the {{runtime_name}} runtime and {{db_name}}.
+pub mod constants {
+	use frame_support::{parameter_types, weights::{RuntimeDbWeight, constants}};
+
+	parameter_types! {
+		{{#if (eq db_name "ParityDb")}}
+		/// ParityDB can be enabled with a feature flag, but is still experimental. These weights
+		/// are available for brave runtime engineers who may want to try this out as default.
+		{{else}}
+		/// By default, Substrate uses RocksDB, so this will be the weight used throughout
+		/// the runtime.
+		{{/if}}
+		pub const {{db_name}}Weight: RuntimeDbWeight = RuntimeDbWeight {
+			/// Time to read one storage item.
+			/// Calculated by multiplying the *{{params.weight_metric}}* of all values with `{{params.weight_mul}}` and adding `{{params.weight_add}}`.
+			///
+			/// Stats [ns]:
+			///   Min, Max: {{underscore read.0.min}}, {{underscore read.0.max}}
+			///   Average:  {{underscore read.0.avg}}
+			///   Median:   {{underscore read.0.median}}
+			///   StdDev:   {{read.0.stddev}}
+			///
+			/// Percentiles [ns]:
+			///   99th: {{underscore read.0.p99}}
+			///   95th: {{underscore read.0.p95}}
+			///   75th: {{underscore read.0.p75}}
+			read: {{underscore read_weight}} * constants::WEIGHT_PER_NANOS,
+
+			/// Time to write one storage item.
+			/// Calculated by multiplying the *{{params.weight_metric}}* of all values with `{{params.weight_mul}}` and adding `{{params.weight_add}}`.
+			///
+			/// Stats [ns]:
+			///   Min, Max: {{underscore write.0.min}}, {{underscore write.0.max}}
+			///   Average:  {{underscore write.0.avg}}
+			///   Median:   {{underscore write.0.median}}
+			///   StdDev:   {{write.0.stddev}}
+			///
+			/// Percentiles [ns]:
+			///   99th: {{underscore write.0.p99}}
+			///   95th: {{underscore write.0.p95}}
+			///   75th: {{underscore write.0.p75}}
+			write: {{underscore write_weight}} * constants::WEIGHT_PER_NANOS,
+		};
+	}
+
+	#[cfg(test)]
+	mod test_db_weights {
+		use super::constants::{{db_name}}Weight as W;
+		use frame_support::weights::constants;
+
+		/// Checks that all weights exist and have sane values.
+		// NOTE: If this test fails but you are sure that the generated values are fine,
+		// you can delete it.
+		#[test]
+		fn bound() {
+			// At least 1 µs.
+			assert!(
+				W::get().reads(1) >= constants::WEIGHT_PER_MICROS,
+				"Read weight should be at least 1 µs."
+			);
+			assert!(
+				W::get().writes(1) >= constants::WEIGHT_PER_MICROS,
+				"Write weight should be at least 1 µs."
+			);
+			// At most 1 ms.
+			assert!(
+				W::get().reads(1) <= constants::WEIGHT_PER_MILLIS,
+				"Read weight should be at most 1 ms."
+			);
+			assert!(
+				W::get().writes(1) <= constants::WEIGHT_PER_MILLIS,
+				"Write weight should be at most 1 ms."
+			);
+		}
+	}
+}
@@ -0,0 +1,131 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2022 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: Apache-2.0
+
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use sc_cli::Result;
+use sc_client_api::UsageProvider;
+use sc_client_db::{DbHash, DbState, DB_HASH_LEN};
+use sp_api::StateBackend;
+use sp_blockchain::HeaderBackend;
+use sp_database::{ColumnId, Transaction};
+use sp_runtime::{
+	generic::BlockId,
+	traits::{Block as BlockT, HashFor, Header as HeaderT},
+};
+use sp_trie::PrefixedMemoryDB;
+
+use log::info;
+use rand::prelude::*;
+use std::{fmt::Debug, sync::Arc, time::Instant};
+
+use super::{cmd::StorageCmd, record::BenchRecord};
+
+impl StorageCmd {
+	/// Benchmarks the time it takes to write a single Storage item.
+	/// Uses the latest state that is available for the given client.
+	pub(crate) fn bench_write<Block, H, C>(
+		&self,
+		client: Arc<C>,
+		(db, state_col): (Arc<dyn sp_database::Database<DbHash>>, ColumnId),
+		storage: Arc<dyn sp_state_machine::Storage<HashFor<Block>>>,
+	) -> Result<BenchRecord>
+	where
+		Block: BlockT<Header = H, Hash = DbHash> + Debug,
+		H: HeaderT<Hash = DbHash>,
+		C: UsageProvider<Block> + HeaderBackend<Block>,
+	{
+		// Store the time that it took to write each value.
+		let mut record = BenchRecord::default();
+
+		let supports_rc = db.supports_ref_counting();
+		let block = BlockId::Number(client.usage_info().chain.best_number);
+		let header = client.header(block)?.ok_or("Header not found")?;
+		let original_root = *header.state_root();
+		let trie = DbState::<Block>::new(storage.clone(), original_root);
+
+		info!("Preparing keys from block {}", block);
+		// Load all KV pairs and randomly shuffle them.
+		let mut kvs = trie.pairs();
+		let mut rng = Self::setup_rng();
+		kvs.shuffle(&mut rng);
+
+		info!("Writing {} keys", kvs.len());
+		// Write each value in one commit.
+		for (k, original_v) in kvs.iter() {
+			// Create a random value to overwrite with.
+			// NOTE: We use a possibly higher entropy than the original value,
+			// could be improved but acts as an over-estimation which is fine for now.
+			let mut new_v = vec![0; original_v.len()];
+			rng.fill_bytes(&mut new_v[..]);
+
+			// Interesting part here:
+			let start = Instant::now();
+			// Create a TX that will modify the Trie in the DB and
+			// calculate the root hash of the Trie after the modification.
+			let replace = vec![(k.as_ref(), Some(new_v.as_ref()))];
+			let (_, stx) = trie.storage_root(replace.iter().cloned(), self.state_version());
+			// Only the keep the insertions, since we do not want to benchmark pruning.
+			let tx = convert_tx::<Block>(stx.clone(), true, state_col, supports_rc);
+			db.commit(tx).map_err(|e| format!("Writing to the Database: {}", e))?;
+			record.append(new_v.len(), start.elapsed())?;
+
+			// Now undo the changes by removing what was added.
+			let tx = convert_tx::<Block>(stx.clone(), false, state_col, supports_rc);
+			db.commit(tx).map_err(|e| format!("Writing to the Database: {}", e))?;
+		}
+		Ok(record)
+	}
+}
+
+/// Converts a Trie transaction into a DB transaction.
+/// Removals are ignored and will not be included in the final tx.
+/// `invert_inserts` replaces all inserts with removals.
+///
+/// The keys of Trie transactions are prefixed, this is treated differently by each DB.
+/// ParityDB can use an optimization where only the last `DB_HASH_LEN` byte are needed.
+/// The last `DB_HASH_LEN` byte are the hash of the actual stored data, everything
+/// before that is the route in the Patricia Trie.
+/// RocksDB cannot do this and needs the whole route, hence no key truncating for RocksDB.
+///
+/// TODO:
+/// This copies logic from [`sp_client_db::Backend::try_commit_operation`] and should be
+/// refactored to use a canonical `sanitize_key` function from `sp_client_db` which
+/// does not yet exist.
+fn convert_tx<B: BlockT>(
+	mut tx: PrefixedMemoryDB<HashFor<B>>,
+	invert_inserts: bool,
+	col: ColumnId,
+	supports_rc: bool,
+) -> Transaction<DbHash> {
+	let mut ret = Transaction::<DbHash>::default();
+
+	for (mut k, (v, rc)) in tx.drain().into_iter() {
+		if supports_rc {
+			let _prefix = k.drain(0..k.len() - DB_HASH_LEN);
+		}
+
+		if rc > 0 {
+			if invert_inserts {
+				ret.set(col, k.as_ref(), &v);
+			} else {
+				ret.remove(col, &k);
+			}
+		}
+		// < 0 means removal - ignored.
+		// 0 means no modification.
+	}
+	ret
+}
@@ -436,7 +436,7 @@ where
 // A Handlebars helper to add an underscore after every 3rd character,
 // i.e. a separator for large numbers.
 #[derive(Clone, Copy)]
-struct UnderscoreHelper;
+pub(crate) struct UnderscoreHelper;
 impl handlebars::HelperDef for UnderscoreHelper {
 	fn call<'reg: 'rc, 'rc>(
 		&self,