Re: [RFC PATCH 0/3] Parallel submodule status

[Benjamin <ben.knoble@gmail.com>]

> This set tries to speed up git status (and other commands which examine the tree state) for repositories with many submodules.

I built these patches on top of master from d6fd04375f (The twelfth batch, 2024-03-28), and that went smoothly. However, I used hyperfine to benchmark the changes in a repo of mine with many submodules (which I have used as a case study for the performance before [1]), and I don’t notice any change:

λ hyperfine 'git status' ~c/git/git-status 'git status --ignore-submodules=all' '~/code/git/git-status --ignore-submodules=all'
Benchmark 1: git status
  Time (mean ± σ):     977.8 ms ±   3.4 ms    [User: 415.4 ms, System: 460.2 ms]
  Range (min … max):   971.5 ms … 983.4 ms    10 runs

Benchmark 2: /Users/Knoble/code/git/git-status
  Time (mean ± σ):     987.0 ms ±   6.0 ms    [User: 419.5 ms, System: 461.5 ms]
  Range (min … max):   980.5 ms … 1000.1 ms    10 runs

Benchmark 3: git status --ignore-submodules=all
  Time (mean ± σ):      29.2 ms ±   0.5 ms    [User: 8.5 ms, System: 19.1 ms]
  Range (min … max):    27.8 ms …  30.4 ms    90 runs

Benchmark 4: ~/code/git/git-status --ignore-submodules=all
  Time (mean ± σ):      32.3 ms ±   0.6 ms    [User: 10.5 ms, System: 19.1 ms]
  Range (min … max):    31.0 ms …  35.0 ms    81 runs

Summary
  git status --ignore-submodules=all ran
    1.11 ± 0.03 times faster than ~/code/git/git-status --ignore-submodules=all
   33.47 ± 0.63 times faster than git status
   33.78 ± 0.66 times faster than /Users/Knoble/code/git/git-status


Is there something I needed to enable to see the speedup (am I « holding it wrong »)? Or is this series not actually implementing the parallelization yet—perhaps it is a series of preparatory commits?

I look forward to an implementation of this feature; searching the mailing list reveals some candidates which don’t appear to have ever made it to master [2].

[1]: https://lore.kernel.org/git/CALnO6CCoXOZTsfag6yN_Ffn+H7KE-KTzm+P-GqLKnDMg8j_Qmg@mail.gmail.com/
[2]: https://lore.kernel.org/git/20220922232947.631309-1-calvinwan@google.com/