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Re: [PATCH v5 02/15] read-cache: allow to keep mmap'd memory after reading

From
Duy Nguyen <pclouds@gmail.com>
Date
Apr 20, 2016, 09:26 UTC
Message-ID
<CACsJy8D229ARqEjH29Gqd=u8KijGA_Fzk0cbUNRXB9GA0ittMg@mail.gmail.com>
In-Reply-To
<1461108489-29376-3-git-send-email-dturner@twopensource.com>
On Wed, Apr 20, 2016 at 6:27 AM, David Turner <dturner@twopensource.com> wrote:
Show 7 quoted lines
> From: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
>
> Later, we will introduce git index-helper to share this memory with
> other git processes.
>
> Since the memory will be shared, it will never be unmapped (although
> the kernel may of course choose to page it out).

This is not entirely true. We do need to keep the mmap'd memory for longer, even after read_index_from() finishes. But we do not share the exact same address space to other processes (memcpy is used in index-helper.c:share_index()). We could even discard_index() at the end of share_index(), but I think we keep it anyway just in case another process asks, or when index is not updated.

-- 
Duy
Previous: David TurnerNext: David Turner
Message 6 of 35 in “index-helper/watchman”
  1. 00/15 index-helper/watchmanDavid Turner, Apr 19, 2016
  2. 01/15 read-cache.c: fix constness of verify_hdr()David Turner, Apr 19, 2016
  3. 02/15 read-cache: allow to keep mmap'd memory after readingDavid Turner, Apr 19, 2016
  4. Johannes SchindelinApr 20, 2016
  5. David TurnerApr 20, 2016
  6. Duy NguyenApr 20, 2016
  7. David TurnerApr 20, 2016
  8. 03/15 index-helper: new daemon for caching index and related stuffDavid Turner, Apr 19, 2016
  9. Johannes SchindelinApr 20, 2016
  10. Duy NguyenApr 20, 2016
  11. David TurnerApr 20, 2016
  12. 04/15 index-helper: add --strictDavid Turner, Apr 19, 2016
  13. 05/15 daemonize(): set a flag before exiting the main processDavid Turner, Apr 19, 2016
  14. 06/15 index-helper: add --detachDavid Turner, Apr 19, 2016
  15. Duy NguyenApr 19, 2016
  16. David TurnerApr 20, 2016
  17. Duy NguyenApr 20, 2016
  18. David TurnerApr 25, 2016
  19. 07/15 read-cache: add watchman 'WAMA' extensionDavid Turner, Apr 19, 2016
  20. 08/15 Add watchman support to reduce index refresh costDavid Turner, Apr 19, 2016
  21. 09/15 index-helper: use watchman to avoid refreshing index with lstat()David Turner, Apr 19, 2016
  22. Duy NguyenApr 20, 2016
  23. David TurnerApr 20, 2016
  24. Duy NguyenApr 20, 2016
  25. 10/15 update-index: enable/disable watchman supportDavid Turner, Apr 19, 2016
  26. Duy NguyenApr 19, 2016
  27. David TurnerApr 20, 2016
  28. 11/15 unpack-trees: preserve index extensionsDavid Turner, Apr 19, 2016
  29. 12/15 index-helper: kill modeDavid Turner, Apr 19, 2016
  30. 13/15 index-helper: don't run if already runningDavid Turner, Apr 19, 2016
  31. 14/15 index-helper: autorun modeDavid Turner, Apr 19, 2016
  32. 15/15 index-helper: optionally automatically runDavid Turner, Apr 19, 2016
  33. 16/15 Add tracing to measure where most of the time is spentNguyễn Thái Ngọc Duy, Apr 20, 2016
  34. Johannes SchindelinApr 20, 2016
  35. Duy NguyenApr 20, 2016

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