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Re: Git and GCC


On 12/7/07, Jeff King <peff@peff.net> wrote:
> On Thu, Dec 06, 2007 at 07:31:21PM -0800, David Miller wrote:
>
> > > 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

64 threads with 64 CPUs, if they are multicore you want even more.
you need to adjust chunk_size as mentioned in the other mail.


> time git repack -a -d -f --window=250 --depth=250
>
> -Peff
>


-- 
Jon Smirl
jonsmirl@gmail.com


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