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Re: [PATCH 3/5] tree-walk: micro-optimization in tree_entry_interesting

From
Junio C Hamano <gitster@pobox.com>
Date
Aug 30, 2011, 20:40 UTC
Message-ID
<7v62le1vlx.fsf@alter.siamese.dyndns.org>
In-Reply-To
<CAEik5nNaDkAa2+63g1z3c1JUB8sLuTLfYP3jLKZJg2=yKqyzDg@mail.gmail.com>
Dan McGee <dpmcgee@gmail.com> writes:
Show 15 quoted lines
>> dmcgee@galway ~/projects/linux-2.6 (master)
>> $ time ../git/git-log -- zzzzz_not_exist > /dev/null
>>
>> real    0m0.945s
>> user    0m0.857s
>> sys     0m0.083s
>>
>>> There is nothing wrong in the patch per-se, but I really wish we didn't
>>> have to do this; it feels like the compiler should be helping us in this
>>> case.
>
> If I resurrect this with an updated commit message reflecting concerns
> raised, can it be merged? Given that it is a noticeable performance
> boost on real-life repositories and I can show it has little (<1%) to
> no impact on most repos, it is a definite win.

I do not see anything wrong in this particular patch per-se, but I really wish we didn't have to do this.

Please include a few lines of benchmarking result in the updated commit log message as well if you are rerolling this patch, perhaps like I did in:

  http://thread.gmane.org/gmane.comp.version-control.git/179926/focus=180361
i.e., before and after comparison.
Thanks.
Previous: Dan McGeeNext: Dan McGee
Message 28 of 30 in “diff_tree_sha1: skip diff_tree if old == new”
  1. 1/5 diff_tree_sha1: skip diff_tree if old == newDan McGee, Mar 31, 2011
  2. 2/5 tree-walk: drop unused parameter from match_dir_prefixDan McGee, Mar 31, 2011
  3. Dan McGeeAug 30, 2011
  4. 3/5 tree-walk: micro-optimization in tree_entry_interestingDan McGee, Mar 31, 2011
  5. Nguyen Thai Ngoc DuyApr 3, 2011
  6. Junio C HamanoApr 3, 2011
  7. Dan McGeeApr 5, 2011
  8. tree_entry_interesting: inline strncmp()Nguyễn Thái Ngọc Duy, Apr 4, 2011
  9. 4/5 tree-walk: unroll get_mode since loop boundaries are well-knownDan McGee, Mar 31, 2011
  10. Nguyen Thai Ngoc DuyApr 2, 2011
  11. Dan McGeeApr 2, 2011
  12. Nguyen Thai Ngoc DuyApr 3, 2011
  13. Erik Faye-LundApr 4, 2011
  14. Andreas EricssonApr 4, 2011
  15. Junio C HamanoApr 4, 2011
  16. Dan McGeeApr 5, 2011
  17. Antriksh PanyApr 5, 2011
  18. Dan McGeeApr 6, 2011
  19. 5/5 tree-walk: match_entry microoptimizationDan McGee, Mar 31, 2011
  20. Nguyen Thai Ngoc DuyApr 2, 2011
  21. Dan McGeeApr 2, 2011
  22. Nguyen Thai Ngoc DuyMar 31, 2011
  23. Dan McGeeMar 31, 2011
  24. Junio C HamanoApr 1, 2011
  25. Nguyen Thai Ngoc DuyMay 3, 2011
  26. Fwd: [PATCH 1/5] diff_tree_sha1: skip diff_tree if old == newDan McGee, Apr 2, 2011
  27. Dan McGeeAug 30, 2011
  28. Junio C HamanoAug 30, 2011
  29. 1/2 tree-walk: drop unused parameter from match_dir_prefixDan McGee, Sep 9, 2011
  30. 2/2 tree-walk: micro-optimization in tree_entry_interestingDan McGee, Sep 9, 2011

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