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Re: [PATCH 11/17] Fully activate the sliding window pack access.

From
Linus Torvalds <torvalds@osdl.org>
Date
Dec 23, 2006, 20:10 UTC
Message-ID
<Pine.LNX.4.64.0612231207400.3671@woody.osdl.org>
In-Reply-To
<7vodpuqtuf.fsf@assigned-by-dhcp.cox.net>
On Sat, 23 Dec 2006, Junio C Hamano wrote:
> 
> I have been thinking that we should perhaps change Cygwin
> default to NO_MMAP.  Safer but slower would be better than not
> working correctly for people on FAT32.

The thing is, with a smaller pack access window, it might not even be slower. I don't know just _how_ many hoops cygwin jumps through for mmap, and maybe mmap under cygwin is actually perfectly fine, but at the same time I do suspect that UNIX mmap semantics are a lot harder to emulate than just a regular "pread()", so it's quite possible that by avoiding mmap you could avoid a lot of complex cygwin code.

And yes, making it all work on FAT32 would obviously be a good thing.
Only testing (or somebody who knows cygwin well) can tell.
			Linus
Previous: Junio C HamanoNext: Johannes Schindelin
Message 16 of 25 in “Replace unpack_entry_gently with unpack_entry.”
  1. 1/17 Replace unpack_entry_gently with unpack_entry.Shawn O. Pearce, Dec 23, 2006
  2. 2/17 Introduce new config option for mmap limit.Shawn O. Pearce, Dec 23, 2006
  3. 3/17 Refactor packed_git to prepare for sliding mmap windows.Shawn O. Pearce, Dec 23, 2006
  4. 4/17 Use off_t for index and pack file lengths.Shawn O. Pearce, Dec 23, 2006
  5. 5/17 Create read_or_die utility routine.Shawn O. Pearce, Dec 23, 2006
  6. 6/17 Refactor how we open pack files to prepare for multiple windows.Shawn O. Pearce, Dec 23, 2006
  7. 7/17 Replace use_packed_git with window cursors.Shawn O. Pearce, Dec 23, 2006
  8. 8/17 Loop over pack_windows when inflating/accessing data.Shawn O. Pearce, Dec 23, 2006
  9. 9/17 Document why header parsing won't exceed a window.Shawn O. Pearce, Dec 23, 2006
  10. 10/17 Unmap individual windows rather than entire files.Shawn O. Pearce, Dec 23, 2006
  11. 11/17 Fully activate the sliding window pack access.Shawn O. Pearce, Dec 23, 2006
  12. Linus TorvaldsDec 23, 2006
  13. Eric BlakeDec 23, 2006
  14. Johannes SchindelinDec 24, 2006
  15. Junio C HamanoDec 23, 2006
  16. Linus TorvaldsDec 23, 2006
  17. Johannes SchindelinDec 24, 2006
  18. Shawn PearceDec 24, 2006
  19. Shawn PearceDec 24, 2006
  20. 12/17 Load core configuration in git-verify-pack.Shawn O. Pearce, Dec 23, 2006
  21. 13/17 Ensure core.packedGitWindowSize cannot be less than 2 pages.Shawn O. Pearce, Dec 23, 2006
  22. 14/17 Improve error message when packfile mmap fails.Shawn O. Pearce, Dec 23, 2006
  23. 15/17 Support unmapping windows on 'temporary' packfiles.Shawn O. Pearce, Dec 23, 2006
  24. 16/17 Create pack_report() as a debugging aid.Shawn O. Pearce, Dec 23, 2006
  25. 17/17 Test suite for sliding window mmap implementation.Shawn O. Pearce, Dec 23, 2006

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