Re:

From: Linus Torvalds <torvalds@linux-foundation.org>
Date: May 8, 2009, 17:44 UTC
Message-ID: <alpine.LFD.2.01.0905081038160.4983@localhost.localdomain>
In-Reply-To: <Ah7lj3UWxgwxNiQs6kqiiVurulv4F00ssWrb3OzfTrXYlK8ZBCSBOQ@cipher.nrlssc.navy.mil>

On Fri, 8 May 2009, Brandon Casey wrote:

Show 12 quoted lines

> 
> Something is definitely up.
> 
> I provided timing results for your original preload_cache implementation
> which affected status and diff, which was part of the justification for
> merging it in.
> 
>    http://article.gmane.org/gmane.comp.version-control.git/100998
> 
> You can see that cold cache system time for 'git status' went from 0.36 to
> 0.52 seconds.  Fine.  I just ran it again, and now I'm getting system time
> of 10 seconds!  This is the same machine.

Grr.

> OS: Centos4.7
> 
> $ cat /proc/version
> Linux version 2.6.9-78.0.17.ELsmp (mockbuild@builder16.centos.org) (gcc version 3.4.6 20060404 (Red Hat 3.4.6-9)) #1 SMP Thu Mar 12 20:05:15 EDT 2009

Ok, if that's really the true kernel version (2.6.9), then that's some ancient kernel there. At the same time it's obviously been recompiled recently, so it got updated. At a guess, something got screwed up. But I have absolutely _no_ way to even guess what kernel patches centos puts in their ancient kernel builds.

Perhaps a centos bugzilla entry might be appropriate? Somebody there might know what changed.

Of course, it _could_ be an external change too, where the NFS server or timing changed just enough to trigger a pre-existing issue. But that would be pretty unlikely.

			Linus