Unrolled build for rust-lang#121781

rust-timer · web-flow · commit aa2d68b5bdb7 · 2024-02-29T11:05:41.000-05:00
Rollup merge of rust-lang#121781 - RalfJung:bootstrap-fmt, r=clubby789 bootstrap/format: send larger batches to rustfmt This helps on systems with low core counts. To benchmark this I made a lot of files be modified: ``` for FILE in $(find compiler/ -name "*.rs"); do echo "// end of the file" >>$FILE; done ``` Then I ran ``` hyperfine "./x.py fmt -j1" -w 1 -r 4 ``` Before this patch: ``` Benchmark 1: ./x.py fmt -j1 Time (mean ± σ): 3.426 s ± 0.032 s [User: 4.681 s, System: 1.376 s] Range (min … max): 3.389 s … 3.462 s 4 runs ``` With this patch: ``` Benchmark 1: ./x.py fmt -j1 Time (mean ± σ): 2.530 s ± 0.054 s [User: 4.042 s, System: 0.467 s] Range (min … max): 2.452 s … 2.576 s 4 runs ```
diff --git a/src/bootstrap/src/core/build_steps/format.rs b/src/bootstrap/src/core/build_steps/format.rs
@@ -279,8 +279,8 @@ pub fn format(build: &Builder<'_>, check: bool, paths: &[PathBuf]) {
     let thread = std::thread::spawn(move || {
         let mut children = VecDeque::new();
         while let Ok(path) = rx.recv() {
-            // try getting a few more paths from the channel to amortize the overhead of spawning processes
-            let paths: Vec<_> = rx.try_iter().take(7).chain(std::iter::once(path)).collect();
+            // try getting more paths from the channel to amortize the overhead of spawning processes
+            let paths: Vec<_> = rx.try_iter().take(63).chain(std::iter::once(path)).collect();
 
             let child = rustfmt(&src, &rustfmt_path, paths.as_slice(), check);
             children.push_back(child);
