From: Linus Torvalds Date: Mon, 27 Jun 2005 05:20:30 GMT Subject: Re: git-local-pull Message-ID: In-Reply-To: <20050626.200555.39157645.davem@davemloft.net> On Sun, 26 Jun 2005, David S. Miller wrote: > > I tried to start using git-clone-script to clone repositories > locally. It crunches on the disk for a couple of seconds, > that's fine, but then I notice the disk activity stop and > git-local-pull becomes cpu bound and grows to 80MB in size > over the course of 5 minutes. Try adding "-l" to the git-local-pull command line, to make it do hardlinks by default (and fall back to a copy if that fails). > Is this a side effect of the new pack/unpack stuff? Nope, nothing uses that yet. I think the 80MB is just because it built up the object relationship for the whole kernel db there. I don't know what the 5 minutes of CPU are, though, it should just be copying stuff (and at 250MB in and 250MB out, that's a lot of stuff to copy, but it shouldn't be five minutes worth, especially if it's all cached and you see a pegged CPU). That copy is stupid, btw. Doing a "mmap + write" is a lot slower than doing a "while (data) { read(8kB) + write(8kB) }" loop. The read() will generally do better read-ahead and the small read/write will be better for the caches. But that still doesn't explain 5 minutes worth. > Compared to what this thing is doing, manually symlinking > the object database, copying over the HEAD, and building > the index file is significantly faster. Well, with "-l" that is what git-local-pull will do too. And if you want symlinks, use "-s". Or use both, in which case it will try a hardlink first, and then a symlink if it gets an EXDEV. Linus