forked from mirrors/jj
84f807d222
This improves `jj status` time by a factor of ~2x on my machine (M1 Macbook Pro 2021 16-inch, uses an SSD):
```sh
$ hyperfine --parameter-list hash before,after --parameter-list repo nixpkgs,gecko-dev --setup 'git checkout {hash} && cargo build --profile release-with-debug' --warmup 3 './target/release-with-debug/jj -R ../{repo} st'
Benchmark 1: ./target/release-with-debug/jj -R ../nixpkgs st (hash = before)
Time (mean ± σ): 1.640 s ± 0.019 s [User: 0.580 s, System: 1.044 s]
Range (min … max): 1.621 s … 1.673 s 10 runs
Benchmark 2: ./target/release-with-debug/jj -R ../nixpkgs st (hash = after)
Time (mean ± σ): 760.0 ms ± 5.4 ms [User: 812.9 ms, System: 2214.6 ms]
Range (min … max): 751.4 ms … 768.7 ms 10 runs
Benchmark 3: ./target/release-with-debug/jj -R ../gecko-dev st (hash = before)
Time (mean ± σ): 11.403 s ± 0.648 s [User: 4.546 s, System: 5.932 s]
Range (min … max): 10.553 s … 12.718 s 10 runs
Benchmark 4: ./target/release-with-debug/jj -R ../gecko-dev st (hash = after)
Time (mean ± σ): 5.974 s ± 0.028 s [User: 5.387 s, System: 11.959 s]
Range (min … max): 5.937 s … 6.024 s 10 runs
$ hyperfine --parameter-list repo nixpkgs,gecko-dev --warmup 3 'git -C ../{repo} status'
Benchmark 1: git -C ../nixpkgs status
Time (mean ± σ): 865.4 ms ± 8.4 ms [User: 119.4 ms, System: 1401.2 ms]
Range (min … max): 852.8 ms … 879.1 ms 10 runs
Benchmark 2: git -C ../gecko-dev status
Time (mean ± σ): 2.892 s ± 0.029 s [User: 0.458 s, System: 14.244 s]
Range (min … max): 2.837 s … 2.934 s 10 runs
```
Conclusions:
- ~2x improvement from previous `jj status` time.
- Slightly faster than Git on nixpkgs.
- Still 2x slower than Git on gecko-dev, not sure why.
For reference, Git's default number of threads is defined in the `online_cpus` function:
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