Add subsystems regression tests to CI (#3527)

Fixes https://github.com/paritytech/polkadot-sdk/issues/3530

polkadot/node/subsystem-bench/src/lib/utils.rs

@@ -0,0 +1,76 @@
+// Copyright (C) Parity Technologies (UK) Ltd.
+// This file is part of Polkadot.
+
+// Polkadot is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Polkadot is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Polkadot.  If not, see <http://www.gnu.org/licenses/>.
+
+//! Test utils
+
+use crate::usage::BenchmarkUsage;
+use std::io::{stdout, Write};
+
+pub struct WarmUpOptions<'a> {
+	/// The maximum number of runs considered for marming up.
+	pub warm_up: usize,
+	/// The number of runs considered for benchmarking.
+	pub bench: usize,
+	/// The difference in CPU usage between runs considered as normal
+	pub precision: f64,
+	/// The subsystems whose CPU usage is checked during warm-up cycles
+	pub subsystems: &'a [&'a str],
+}
+
+impl<'a> WarmUpOptions<'a> {
+	pub fn new(subsystems: &'a [&'a str]) -> Self {
+		Self { warm_up: 100, bench: 3, precision: 0.02, subsystems }
+	}
+}
+
+pub fn warm_up_and_benchmark(
+	options: WarmUpOptions,
+	run: impl Fn() -> BenchmarkUsage,
+) -> Result<BenchmarkUsage, String> {
+	println!("Warming up...");
+	let mut usages = Vec::with_capacity(options.bench);
+
+	for n in 1..=options.warm_up {
+		let curr = run();
+		if let Some(prev) = usages.last() {
+			let diffs = options
+				.subsystems
+				.iter()
+				.map(|&v| {
+					curr.cpu_usage_diff(prev, v)
+						.ok_or(format!("{} not found in benchmark {:?}", v, prev))
+				})
+				.collect::<Result<Vec<f64>, String>>()?;
+			if !diffs.iter().all(|&v| v < options.precision) {
+				usages.clear();
+			}
+		}
+		usages.push(curr);
+		print!("\r{}%", n * 100 / options.warm_up);
+		if usages.len() == options.bench {
+			println!("\rTook {} runs to warm up", n.saturating_sub(options.bench));
+			break;
+		}
+		stdout().flush().unwrap();
+	}
+
+	if usages.len() != options.bench {
+		println!("Didn't warm up after {} runs", options.warm_up);
+		return Err("Can't warm up".to_string())
+	}
+
+	Ok(BenchmarkUsage::average(&usages))
+}