Re: [PATCH] speedup allocation in pack-redundant.c

From: Alex Riesen <raa.lkml@gmail.com>
Date: Nov 22, 2005, 23:46 UTC
Message-ID: <20051122234622.GD2916@steel.home>
In-Reply-To: <4383A053.8020100@etek.chalmers.se>

Lukas Sandström, Tue, Nov 22, 2005 23:48:51 +0100:

Show 13 quoted lines

> >>Subject: [PATCH] speedup allocation in pack-redundant.c
> >>Reuse discarded nodes of llists
> >>Signed-off-by: Alex Riesen <ariesen@harmanbecker.com>
> > 
> > I think making allocation/deallocation to the central place is a
> > good cleanup, but I am not sure about the free-nodes reusing.
> > Does this make difference in real life?  If so, it might be
> > worth doing the slab-like allocation, since free-nodes are very
> > small structure and malloc overhead is not ignorable there.
> > 
> I have done some tests, and unfortunatley I saw approx. zero
> improvement with Alex's patch. (less than 10ms difference when
> total runtime is 1.850s, tested on http://home.arcor.de/fork0/download/idx.tar.gz)

Can I suggest you try it in a really really weird environment? Like Cygwin. And switch some virus scanner on.

> Did someone else notice an improvement?

My test case had over 100k files in it (just don't ask why. Weird environments, weird projects, ...)

> It's a nice idea though. I'll look into doing slab-allocation
> for the fun of it, but I'm not really sure that malloc is the
> bottleneck.

Yes, it usually is not a bottleneck. I think, it just another exception.