Jeff King <peff@xxxxxxxx> 于2021年9月5日周日 下午8:49写道： > > On Sun, Sep 05, 2021 at 04:19:53PM +0800, ZheNing Hu wrote: > > > > In this version there are 2 patches, tested against 'git for-each-ref > > > --format="%(objectname) %(refname)"' on a fully packed repo with 500k > > > refs: > > > > > > > Regarding this 500k refs, is there any way I can reproduce it? > > Try this in a clone of linux.git (or any other repo): > > git rev-list HEAD | > head -500000 | > perl -lne 'print "create refs/foo/$. $_"' | > git update-ref --stdin > > git pack-refs --all --prune > Sorry, It seems that the above command is difficult to complete on my machine (it took more than ten minutes). It may be stuck on git update-ref. So I tried to reproduce it in a repo which containing 76K refs: Benchmark #1: jk-for-each-ref-speedup~2: git for-each-ref --format='%(refname) %(objectname)' Time (mean ± σ): 108.0 ms ± 1.9 ms [User: 55.2 ms, System: 52.1 ms] Range (min … max): 105.7 ms … 112.4 ms 26 runs Benchmark #2: jk-for-each-ref-speedup~1: git for-each-ref --format='%(refname) %(objectname)' Time (mean ± σ): 88.2 ms ± 1.7 ms [User: 44.8 ms, System: 43.1 ms] Range (min … max): 85.8 ms … 93.2 ms 32 runs Benchmark #3:jk-for-each-ref-speedup: git for-each-ref --format='%(refname) %(objectname)' Time (mean ± σ): 69.0 ms ± 2.0 ms [User: 22.7 ms, System: 46.1 ms] Range (min … max): 66.2 ms … 74.1 ms 41 runs For %(refname) and %(objectname), this performance optimization is indeed amazing. > Though I actually think for these tests that it is not important that > each ref point to a unique commit (we are not opening up the objects at > all, and just treating the oids as strings). > > -Peff Thanks. -- ZheNing Hu
