On Fri, 5 Jan 2007, Junio C Hamano wrote: > > The problem Linus pointed out was that your SHA1_Update() > implementations may not be prepared to hash the whole 2.3GB in > one go. The one in "master" (and "maint", although I haven't > done a v1.4.4.4 maintenance release yet) calls SHA1_Update() > in chunks to work around that potential issue. Well, I think Chris is worried about having it all mapped at the same time. It does actually end up forcing the kernel to do more work (it's harder to re-use a mapped page than it is to reuse one that isn't), and in that sense, if you have less than <n> GB of RAM and can't just keep it all in memory at the same time, doing one large mmap is possibly more expensive than chunking things up. That said, I doubt it's a huge problem. If you can't fit the whole file in memory, your real performance issue is going to be the IO, not the fact that the kernel has to work a bit harder at unmapping pages ;) Linus - To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html