From: Jeff King <peff@peff.net>
To: David Kastrup <dak@gnu.org>
Cc: git@vger.kernel.org
Subject: Re: diffcore-rename performance mode
Date: Tue, 25 Sep 2007 15:52:20 -0400 [thread overview]
Message-ID: <20070925195220.GA19549@segfault.peff.net> (raw)
In-Reply-To: <86641y4k34.fsf@lola.quinscape.zz>
On Tue, Sep 25, 2007 at 09:32:31PM +0200, David Kastrup wrote:
> > | stock | nofree | old somefree | fixed somefree
> > -----------------|-----------------------------------------------
> > user time (s) | 76.78 | 16.96 | 46.26 | 16.99
> > peak memory (Kb) | 52300 | 66796 | 59156 | 57328
> >
> > So now we're at a 4.5x speedup for about 10% extra memory usage. Patch
> > will follow.
>
> Sounds good except when we happen to just hit the "memory working set
> exceeds physical memory" sweet spot. But the odds are much better
> than for "nofree".
Of course, there is the possibility that it is the 10% that pushes you
into swap (or kills your ability to cache the entire pack in RAM).
However, this is probably not a big deal for two reasons:
1. this is a 50M process handling the linux-2.6 repository. Other
operations such as repacking already consume significantly more
memory (git-repack -a allocates 290M on the same repo).
2. I specifically turned off rename limiting (-l0) to do rename
detection on these large-ish diffs. If you have a machine which is
on the cusp of swapping, then don't do that. Jumping from -l100
(the default) to -l0 in my tests is _already_ moving you from 28M
to 52M, a much larger jump.
-Peff
next prev parent reply other threads:[~2007-09-25 19:52 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-18 8:23 diffcore-rename performance mode Jeff King
2007-09-18 8:49 ` Junio C Hamano
2007-09-18 8:54 ` Jeff King
2007-09-18 8:58 ` Junio C Hamano
2007-09-18 9:01 ` Jeff King
2007-09-18 9:17 ` Junio C Hamano
2007-09-18 11:20 ` Johannes Schindelin
2007-09-25 16:38 ` Jeff King
2007-09-25 19:06 ` Jeff King
2007-09-25 19:10 ` Andreas Ericsson
2007-09-25 19:32 ` David Kastrup
2007-09-25 19:52 ` Jeff King [this message]
2007-09-18 22:12 ` Linus Torvalds
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