Re: Partitioned packs

From: David Lang <david.lang@digitalinsight.com>
Date: Apr 4, 2007, 01:16 UTC
Message-ID: <Pine.LNX.4.63.0704031813100.21680@qynat.qvtvafvgr.pbz>
In-Reply-To: <db69205d0704031836u3b3dfc2pb9825dd649aca58@mail.gmail.com>

On Tue, 3 Apr 2007, Chris Lee wrote:

Show 15 quoted lines

> Date: Tue, 3 Apr 2007 18:36:44 -0700
> From: Chris Lee <clee@kde.org>
> To: git@vger.kernel.org
> Subject: Partitioned packs
> 
> I've been running some experiments, as hinted earlier by the
> discussion about just how much git-index-pack sucks (which, really,
> isn't much since the gaping memleak is gone now).
>
> These experiments include trying to see if there's a noticeable
> performance improvement by splitting out objects of different types
> into different packs. So far, it definitely seems to make a
> difference, though not the one I was initially expecting. For all of
> these tests, I did 'sysctl -w vm.drop_caches=3' before running, to
> effectively simulate a cold-cache run.

I wonder what order the packs ended up in. if git had to go through the wrong pack completely first before finding the pack that it needed, that coudl account for extra time.

is it worth makeing up single packs that order the three different types of object differently within the one pack to see what difference it makes to have to walk past all the blobs to get to the commits and trees?

David Lang