Re: Cygwin can't handle huge packfiles?

Hi,

On Mon, 3 Apr 2006, Linus Torvalds wrote:

On Mon, 3 Apr 2006, Johannes Schindelin wrote:

quoted

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