weihanglo
commented
1 month ago Originally posted at https://github.com/rust-lang/cargo/issues/14136#issuecomment-2430876726.
Here is a result of a performance benchmark that mostly tests the rustc part.
- It adds
aws-sdk-ec2@1.80.0as a dependency and runscargo clean && cargo check. rg 'checksum:blake3' target/debug/deps | wc -lshows 8313 matches. It means rustc roughly computes blake3 checksum 8313 times.- Checksum computations on Cargo side are mostly ignored because Cargo assumes registry are immutable and won't do either mtime or checksum check .
Result: On par if you have zero local code.
| Command | Mean [s] | Min [s] | Max [s] | Relative |
|---|---|---|---|---|
cargo +nightly check --frozen |
52.986 ± 0.366 | 52.549 | 53.681 | 1.00 |
cargo +nightly check --frozen -Zchecksum-freshness |
53.020 ± 0.315 | 52.442 | 53.480 | 1.00 ± 0.01 |
Benchmark details
Setup package ```shell cargo new foo --lib cd foo cargo add aws-sdk-ec2 ``` Benchmark script ```shell hyperfine --warmup 1 \ --setup "cargo fetch" \ --min-runs 20 \ --prepare "cargo clean" \ --export-markdown result.md \ "cargo +nightly check --frozen" \ "cargo +nightly check --frozen -Zchecksum-freshness" ``` Platform information ``` cargo 1.82.0 (8f40fc59f 2024-08-21) release: 1.82.0 commit-hash: 8f40fc59fb0c8df91c97405785197f3c630304ea commit-date: 2024-08-21 host: x86_64-unknown-linux-gnu libgit2: 1.8.1 (sys:0.19.0 vendored) libcurl: 8.9.0-DEV (sys:0.4.74+curl-8.9.0 vendored ssl:OpenSSL/1.1.1w) ssl: OpenSSL 1.1.1w 11 Sep 2023 os: Amazon Linux AMI 2.0.0 [64-bit] (r7a.24xlarge) ```
@Xaeroxe
Xaeroxe
bjorn3
scottlamb
This issue is intended for tracking performance related discussion and benchmarks for #14136. #14136 itself is for overall progress reports.
Useful cargo script to summarize number and size of files got checksum'd
```rust #!/usr/bin/env cargo ---cargo [dependencies] walkdir = "2" --- use std::collections::HashMap; use std::ffi::OsStr; use std::fs::File; use std::io::prelude::*; use std::io::BufReader; fn main() -> Result<(), Box> {
let walker = walkdir::WalkDir::new("target/debug/deps")
.into_iter()
.filter_entry(|e| e.file_type().is_dir() || e.path().extension() == Some(OsStr::new("d")));
let mut map = HashMap::with_capacity(8192);
for entry in walker {
let entry = entry?;
if entry.file_type().is_dir() {
continue;
}
for line in BufReader::new(File::open(entry.path())?).lines() {
let line = line?;
let Some(rest) = line.strip_prefix("# checksum:") else {
continue;
};
let mut parts = rest.splitn(3, ' ');
let (_, size, path) = (parts.next(), parts.next().unwrap(), parts.next().unwrap());
let size: u64 = size.strip_prefix("file_len:").unwrap().parse()?;
if let Some(old_size) = map.insert(path.to_string(), size) {
assert_eq!(old_size, size, "size doesn't match for {path}: {old_size} vs {size}");
}
}
}
let mut stdout = std::io::stdout().lock();
writeln!(stdout, "number of files: {}", map.len())?;
writeln!(stdout, "total file size: {}", map.values().sum::())?;
Ok(())
}
```