Try to increase priority of processes using runtime benchmarks

Author: Kobzol

Cargo.lock

@@ -13,6 +13,7 @@ serde_json = "1.0.83"
 log = "0.4.17"
 env_logger = "0.9.0"
 clap = { version = "3.2", features = ["derive"] }
+libc = "0.2"
 
 [target.'cfg(unix)'.dependencies]
 perf-event = "0.4.7"

collector/benchlib/Cargo.toml

@@ -1,6 +1,7 @@
 use crate::cli::{parse_cli, Args, BenchmarkArgs};
 use crate::measure::benchmark_function;
 use crate::messages::BenchmarkResult;
+use crate::process::raise_process_priority;
 use log::LevelFilter;
 use std::collections::HashMap;
 
@@ -48,6 +49,8 @@ impl BenchmarkSuite {
     /// Execute the benchmark suite. It will parse CLI arguments and decide what to do based on
     /// them.
     pub fn run(self) -> anyhow::Result<()> {
+        raise_process_priority();
+
         let args = parse_cli()?;
         match args {
             Args::Benchmark(args) => {

collector/benchlib/src/benchmark.rs

@@ -1,5 +1,6 @@
-//! This library defines an API for performing benchmarks of Rust code. It is tailored for the
-//! use-case of `rustc-perf`, that's why we don't use e.g. `criterion` or `iai`.
+//! This library defines an API for performing benchmarks of Rust code and various other utilities
+//! for measuring and benchmarking. It is tailored for the use-case of `rustc-perf`, that's why we
+//! don't use e.g. `criterion` or `iai`.
 //!
 //! We want to be able to define short benchmarks in code, measure specific perf. counters and most
 //! importantly, consume the benchmark results in a programmatic way.
@@ -16,3 +17,4 @@ pub mod benchmark;
 mod cli;
 pub mod measure;
 pub mod messages;
+pub mod process;

collector/benchlib/src/lib.rs

@@ -0,0 +1,16 @@
+#[cfg(unix)]
+pub fn raise_process_priority() {
+    unsafe {
+        // Try to reduce jitter in wall time by increasing our priority to the
+        // maximum
+        for i in (1..21).rev() {
+            let r = libc::setpriority(libc::PRIO_PROCESS as _, libc::getpid() as libc::id_t, -i);
+            if r == 0 {
+                break;
+            }
+        }
+    }
+}
+
+#[cfg(windows)]
+pub fn raise_process_priority() {}

collector/benchlib/src/process.rs

@@ -68,7 +68,7 @@ fn main() {
         let wrapper = args.remove(pos);
         let wrapper = wrapper.to_str().unwrap();
 
-        raise_priority();
+        benchlib::process::raise_process_priority();
 
         // These strings come from `PerfTool::name()`.
         match wrapper {
@@ -490,20 +490,6 @@ fn exec(cmd: &mut Command) -> ! {
     panic!("failed to exec `{}`: {}", cmd_d, error);
 }
 
-#[cfg(unix)]
-fn raise_priority() {
-    unsafe {
-        // Try to reduce jitter in wall time by increasing our priority to the
-        // maximum
-        for i in (1..21).rev() {
-            let r = libc::setpriority(libc::PRIO_PROCESS as _, libc::getpid() as libc::id_t, -i);
-            if r == 0 {
-                break;
-            }
-        }
-    }
-}
-
 #[cfg(unix)]
 fn print_memory() {
     use std::mem;
@@ -555,8 +541,5 @@ fn run_summarize(name: &str, prof_out_dir: &Path, prefix: &str) -> anyhow::Resul
     fs::read_to_string(&json).with_context(|| format!("failed to read {:?}", json))
 }
 
-#[cfg(windows)]
-fn raise_priority() {}
-
 #[cfg(windows)]
 fn print_memory() {}