Re: Cygwin can't handle huge packfiles?

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi,

On Mon, 3 Apr 2006, Linus Torvalds wrote:

> On Mon, 3 Apr 2006, Johannes Schindelin wrote:
> > 
> > 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.
> 
> Well, we could actually do a _real_ mmap on pack-files. The pack-files are 
> much better mmap'ed - there we don't _want_ them to be removed while we're 
> using them. It was the index file etc that was problematic.
> 
> Maybe the cygwin fake mmap should be triggered only for the index (and 
> possibly the individual objects - if only because there doing a 
> malloc+read may actually be faster).

I hit the problem *only* with "git-whatchanged -p". Which means that the 
upcoming we-no-longer-write-temp-files-for-diff version should make that 
gitfakemmap() hack obsolete. (I have not checked whether there are other 
places where a file is mmap()ed and then used by a fork()ed process.)

Ciao,
Dscho