Re: Git and GCC

From: Jeff King <peff@peff.net>
Date: Dec 7, 2007, 06:38 UTC
Message-ID: <20071207063848.GA13101@coredump.intra.peff.net>
In-Reply-To: <20071206.193121.40404287.davem@davemloft.net>

On Thu, Dec 06, 2007 at 07:31:21PM -0800, David Miller wrote:

Show 8 quoted lines

> > So it is about 5% bigger. What is really disappointing is that we saved
> > only about 20% of the time. I didn't sit around watching the stages, but
> > my guess is that we spent a long time in the single threaded "writing
> > objects" stage with a thrashing delta cache.
> 
> If someone can give me a good way to run this test case I can
> have my 64-cpu Niagara-2 box crunch on this and see how fast
> it goes and how much larger the resulting pack file is.

That would be fun to see. The procedure I am using is this:

# compile recent git master with threaded delta cd git echo THREADED_DELTA_SEARCH = 1 >>config.mak make install

# get the gcc pack
mkdir gcc && cd gcc
git --bare init
git config remote.gcc.url git://git.infradead.org/gcc.git
git config remote.gcc.fetch \
  '+refs/remotes/gcc.gnu.org/*:refs/remotes/gcc.gnu.org/*'
git remote update

# make a copy, so we can run further tests from a known point cd .. cp -a gcc test

# and test multithreaded large depth/window repacking cd test git config pack.threads 4 time git repack -a -d -f --window=250 --depth=250

-Peff