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Re: Poor performance of git describe in big repos

From
Duy Nguyen <pclouds@gmail.com>
Date
May 30, 2013, 13:20 UTC
Message-ID
<CACsJy8A1oEezNeFjXTrQ=+gJ6nxDheFYTU0xtiSRt0aOOvE=Vw@mail.gmail.com>
In-Reply-To
<CAJ-05NM9EhikDBP0izqWrnLbZW6RcHq_cH-20YTE08SZw5fjqA@mail.gmail.com>
On Thu, May 30, 2013 at 7:29 PM, Alex Bennée <kernel-hacker@bennee.com> wrote:
Show 9 quoted lines
> I ran perf on it and the top items in the report where:
>
>  41.58%   git  libcrypto.so.1.0.0  [.] 0x6ae73
>  33.96%   git  libz.so.1.2.3.4     [.] 0xe0ec
>  10.39%   git  libz.so.1.2.3.4     [.] adler32
>   2.03%   git  [kernel.kallsyms]   [k] clear_page_c
>
> So I'm guessing it's spending a lot of non-cache efficient time
> un-packing and processing the deltas?

If I'm not mistaken, commits are never deltified. They are usually small and packed close together for better I/O patterns. If you really just read hundreds of commits, it can't take that long. Maybe some code paths accidentally open a tree, a blob or something..

Can you try setting core.logpackaccess to a path on and rerun describe? Jugding from the code (I never actually tried it), it'll create a file at the given path with the accessed pack offsets. You can check what offset corresponds to what object with verify-pack -v. -- Duy

Previous: Alex BennéeNext: Alex Bennée
Message 30 of 33 in “Poor performance of git describe in big repos”
  1. Alex BennéeMay 30, 2013
  2. Ramkumar RamachandraMay 30, 2013
  3. Alex BennéeMay 30, 2013
  4. Ramkumar RamachandraMay 30, 2013
  5. Alex BennéeMay 30, 2013
  6. Ramkumar RamachandraMay 30, 2013
  7. Thomas RastMay 30, 2013
  8. Alex BennéeMay 30, 2013
  9. Thomas RastMay 30, 2013
  10. Thomas RastMay 30, 2013
  11. Antoine PelisseMay 30, 2013
  12. John KeepingMay 30, 2013
  13. Alex BennéeMay 31, 2013
  14. Thomas RastMay 31, 2013
  15. Alex BennéeMay 31, 2013
  16. Thomas RastMay 31, 2013
  17. Alex BennéeMay 31, 2013
  18. Alex BennéeJun 3, 2013
  19. Junio C HamanoJun 3, 2013
  20. Junio C HamanoJun 3, 2013
  21. Thomas RastMay 31, 2013
  22. Jeff KingMay 31, 2013
  23. Alex BennéeJun 3, 2013
  24. Jeff KingJun 3, 2013
  25. John KeepingMay 31, 2013
  26. Alex BennéeMay 31, 2013
  27. John KeepingMay 31, 2013
  28. John KeepingMay 30, 2013
  29. Alex BennéeMay 30, 2013
  30. Duy NguyenMay 30, 2013
  31. Alex BennéeMay 30, 2013
  32. Duy NguyenMay 30, 2013
  33. Alex BennéeMay 30, 2013

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