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Re: [PATCH v2 3/3] grep: disable threading in all but worktree case

From
Nguyen Thai Ngoc Duy <pclouds@gmail.com>
Date
Dec 25, 2011, 03:32 UTC
Message-ID
<CACsJy8AU+a6bHa4qGX0eYgdnP6+PhP7q0pty+bHLBupwr9LCMw@mail.gmail.com>
In-Reply-To
<20111224070715.GA32267@sigill.intra.peff.net>
On Sat, Dec 24, 2011 at 2:07 PM, Jeff King <peff@peff.net> wrote:
Show 19 quoted lines
> The case where we would most expect the setup cost to be drowned out is
> using a more complex regex, grepping tree objects. There we have a
> baseline of:
>
>  $ time git grep 'a.*c' HEAD >/dev/null
>  real    0m5.684s
>  user    0m5.472s
>  sys     0m0.196s
>
>  $ time git ls-tree --name-only -r HEAD |
>      xargs git grep 'a.*c' HEAD -- >/dev/null
>  real    0m10.906s
>  user    0m10.725s
>  sys     0m0.240s
>
> Here, we still almost double our time. It looks like we don't use the
> same pathspec matching code in this case. But we do waste a lot of extra
> time zlib-inflating the trees in "ls-tree", only to do it separately in
> "grep".
Or you could pass blob SHA-1 to git grep to avoid reinflating trees
$ time git ls-tree -r HEAD|cut -c 13-52|xargs git grep 'a.*c' >/dev/null
Doing it in parallel does not seem to save time for me though.
-- 
Duy
Previous: Jeff KingNext: Jeff King
Message 30 of 35 in “grep multithreading and scaling”
  1. 0/3 grep multithreading and scalingThomas Rast, Dec 2, 2011
  2. 1/3 grep: load funcname patterns for -WThomas Rast, Dec 2, 2011
  3. 2/3 grep: enable threading with -p and -W using lazy attribute lookupThomas Rast, Dec 2, 2011
  4. 3/3 grep: disable threading in all but worktree caseThomas Rast, Dec 2, 2011
  5. René ScharfeDec 2, 2011
  6. Thomas RastDec 5, 2011
  7. René ScharfeDec 6, 2011
  8. 4/2 grep: turn off threading for non-worktreeRené Scharfe, Dec 6, 2011
  9. Jeff KingDec 7, 2011
  10. René ScharfeDec 7, 2011
  11. Jeff KingDec 7, 2011
  12. J. Bruce FieldsDec 7, 2011
  13. Jeff KingDec 7, 2011
  14. Thomas RastDec 7, 2011
  15. René ScharfeDec 7, 2011
  16. Pete WyckoffDec 10, 2011
  17. René ScharfeDec 12, 2011
  18. Jeff KingDec 7, 2011
  19. René ScharfeDec 7, 2011
  20. Jeff KingDec 7, 2011
  21. Thomas RastDec 7, 2011
  22. René ScharfeDec 7, 2011
  23. Ævar Arnfjörð BjarmasonDec 23, 2011
  24. Thomas RastDec 23, 2011
  25. Ævar Arnfjörð BjarmasonDec 24, 2011
  26. Jeff KingDec 24, 2011
  27. Nguyen Thai Ngoc DuyDec 24, 2011
  28. Nguyen Thai Ngoc DuyDec 24, 2011
  29. Jeff KingDec 24, 2011
  30. Nguyen Thai Ngoc DuyDec 25, 2011
  31. Jeff KingDec 2, 2011
  32. Thomas RastDec 5, 2011
  33. Thomas RastDec 5, 2011
  34. Jeff KingDec 6, 2011
  35. Eric HermanDec 2, 2011

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