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Re: Cygwin can't handle huge packfiles?

From
Johannes Schindelin <johannes.schindelin@gmx.de>
Date
Apr 3, 2006, 13:23 UTC
Message-ID
<Pine.LNX.4.63.0604031521170.4011@wbgn013.biozentrum.uni-wuerzburg.de>
In-Reply-To
<fa0b6e200604030246q21fccb9ar93004ac67d8b28b3@mail.gmail.com>
Hi,
On Mon, 3 Apr 2006, Kees-Jan Dijkzeul wrote:
Show 16 quoted lines
> I'm trying to get Git to manage a 5Gb source tree. Under linux, this
> works like a charm. Under cygwin, however, I run in to difficulties.
> For example:
> 
> $ git-clone sgp-wa/ sgp-wa.clone
> fatal: packfile
> ./objects/pack/pack-56aa013a0234e198467ed37ae5db925764a6ee98.pack
> cannot be mapped.
> fatal: unexpected EOF
> fetch-pack from '/cygdrive/e/Projects/sgp-wa/.git' failed.
> 
> To figure out what is happening, I printed the value of errno, which
> turns out to be 12 (Cannot allocate memory). I'm not sure how mmap is
> implemented in cygwin, but if they allocate memory and load the file
> into it, then this error is not surprising, as the pack file in
> question is 1.5Gb in size.

The problem is not mmap() on cygwin, but that a fork() has to jump through loops to reinstall the open file descriptors on cygwin. If the corresponding file was deleted, that fails. Therefore, we work around that on cygwin by actually reading the file into memory, *not* mmap()ing it.

Hth, Dscho

Previous: Kees-Jan DijkzeulNext: Morten Welinder
Message 2 of 18 in “Cygwin can't handle huge packfiles?”
  1. Kees-Jan DijkzeulApr 3, 2006
  2. Johannes SchindelinApr 3, 2006
  3. Morten WelinderApr 3, 2006
  4. Linus TorvaldsApr 3, 2006
  5. Linus TorvaldsApr 3, 2006
  6. Kees-Jan DijkzeulApr 5, 2006
  7. Johannes SchindelinApr 5, 2006
  8. Christopher FaylorApr 5, 2006
  9. Rutger NijlunsingApr 5, 2006
  10. Christopher FaylorApr 6, 2006
  11. Junio C HamanoApr 6, 2006
  12. Junio C HamanoApr 7, 2006
  13. Jakub NarebskiApr 7, 2006
  14. Nicolas PitreApr 7, 2006
  15. Junio C HamanoApr 7, 2006
  16. Nicolas PitreApr 7, 2006
  17. Johannes SchindelinApr 3, 2006
  18. Alex RiesenApr 3, 2006

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