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Re: Not going beyond symbolic links

From
Junio C Hamano <gitster@pobox.com>
Date
Aug 8, 2008, 20:55 UTC
Message-ID
<7vod43b519.fsf@gitster.siamese.dyndns.org>
In-Reply-To
<7vk5etjozt.fsf@gitster.siamese.dyndns.org>
Junio C Hamano <gitster@pobox.com> writes:
Show 28 quoted lines
> Linus Torvalds <torvalds@linux-foundation.org> writes:
>
>> On Mon, 4 Aug 2008, Junio C Hamano wrote:
>>> 
>>> I started to revisit this issue and patched "git update-index --add"
>>> and "git add" so far.  Patches follow.
>>
>> Patches look good to me, but did you check the performance impact?
>>
>> The rewritten 'has_symlink_leading_path()' should do ok, but it migth 
>> still be a huge performance downside to check all the paths for things 
>> like "git add -u".
>
> I couldn't quite measure much meaningful performance impact.
>
> My test repository was the kernel tree at v2.6.27-rc2-20-g685d87f, without
> any build products nor editor temporary crufts.
>
> By the way, if anybody wants to reproduce this, be careful with the tests
> that run "rm -f .git/index" before adding everything.  After doing so, if
> you check the result with "git diff --stat HEAD", you will notice many
> missing files --- I almost got a heart attack before inspecting this file:
>
> 	$ cat arch/powerpc/.gitignore
>         include
>
> Yes, it excludes 261 already tracked files.  Is it intended?  I dunno.
> ...

Seeing that you applied my arch/powerpc/.gitignore patch to the kernel (Yaay, I now have a short-log entry in the kernel history ;-), you have seen the message with some benchmarks I am replying to as well?

I actually was expecting to see measurable slowdown by checking leading symbolic link more often, but I couldn't, which means either there is not much downside that the bugfix would hurt real-life usage, or I was too incompetent to come up with an example to show that the bugfix actually hurts the performance.

If the former, I think it is a very good news (If the latter, well, we have a bigger problem :-<), as the affected codepaths are exactly the ones that need to be fixed when somebody tries to add files in a submodule directory by mistake, which is an issue (iirc) Dscho had a separate patch to fix earlier. Tracked symbolic links may be rare, but it seems that many people are using submodules, and that case cannot be hand-waved around by calling it is a feature.

Previous: Junio C HamanoNext: Linus Torvalds
Message 47 of 56 in “Submodule support in git mv, git rm”
  1. Petr BaudisJul 16, 2008
  2. 1/7 git-mv: Remove dead code branchPetr Baudis, Jul 16, 2008
  3. 2/7 t7400: Add short "git submodule add" testsuitePetr Baudis, Jul 16, 2008
  4. 3/7 git submodule add: Fix naming clash handlingPetr Baudis, Jul 16, 2008
  5. 4/7 submodule.*: Introduce simple C interface for submodule lookup by pathPetr Baudis, Jul 16, 2008
  6. 5/7 git mv: Support moving submodulesPetr Baudis, Jul 16, 2008
  7. Junio C HamanoJul 17, 2008
  8. Petr BaudisJul 17, 2008
  9. git-mv: Keep moved index entries inactPetr Baudis, Jul 17, 2008
  10. git mv: Support moving submodulesPetr Baudis, Jul 17, 2008
  11. Junio C HamanoJul 19, 2008
  12. Petr BaudisJul 21, 2008
  13. [PATCHv2] git-mv: Keep moved index entries inactPetr Baudis, Jul 21, 2008
  14. Junio C HamanoJul 21, 2008
  15. Junio C HamanoJul 26, 2008
  16. Petr BaudisJul 27, 2008
  17. t/t7001-mv.sh: Propose ability to use git-mv on conflicting entriesPetr Baudis, Jul 27, 2008
  18. Junio C HamanoJul 28, 2008
  19. Junio C HamanoJul 28, 2008
  20. SZEDER GáborJul 28, 2008
  21. Johannes SchindelinJul 28, 2008
  22. Johannes SchindelinJul 28, 2008
  23. Johannes SchindelinJul 28, 2008
  24. Junio C HamanoJul 28, 2008
  25. Johannes SchindelinJul 28, 2008
  26. Johannes SchindelinJul 28, 2008
  27. Petr BaudisJul 29, 2008
  28. Junio C HamanoJul 29, 2008
  29. Junio C HamanoJul 29, 2008
  30. Not going beyond symbolic linksJunio C Hamano, Aug 4, 2008
  31. 1/2 update-index: refuse to add working tree items beyond symlinksJunio C Hamano, Aug 4, 2008
  32. 2/2 add: refuse to add working tree items beyond symlinksJunio C Hamano, Aug 4, 2008
  33. Linus TorvaldsAug 5, 2008
  34. Junio C HamanoAug 5, 2008
  35. Linus TorvaldsAug 5, 2008
  36. Johannes SchindelinAug 5, 2008
  37. Linus TorvaldsAug 5, 2008
  38. Junio C HamanoAug 5, 2008
  39. Dmitry PotapovAug 5, 2008
  40. Junio C HamanoAug 5, 2008
  41. Linus TorvaldsAug 5, 2008
  42. Junio C HamanoAug 5, 2008
  43. Johannes SchindelinAug 5, 2008
  44. Junio C HamanoAug 5, 2008
  45. david@lang.hmAug 5, 2008
  46. Junio C HamanoAug 7, 2008
  47. Junio C HamanoAug 8, 2008
  48. Linus TorvaldsAug 8, 2008
  49. Johannes SchindelinJul 21, 2008
  50. Petr BaudisJul 21, 2008
  51. Junio C HamanoJul 21, 2008
  52. 6/7 git rm: Support for removing submodulesPetr Baudis, Jul 16, 2008
  53. Johannes SchindelinJul 16, 2008
  54. Petr BaudisJul 17, 2008
  55. Johannes SchindelinJul 17, 2008
  56. 7/7 t7403: Submodule git mv, git rm testsuitePetr Baudis, Jul 16, 2008

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