Re: Something is broken in repack

> On 12/10/07, Nicolas Pitre <nico@cam.org> wrote:
> > On Mon, 10 Dec 2007, Jon Smirl wrote:
> >
> > > New run using same configuration. With the addition of the more
> > > efficient load balancing patches and delta cache accounting.
> > >
> > > Seconds are wall clock time. They are lower since the patch made
> > > threading better at using all four cores. I am stuck at 380-390% CPU
> > > utilization for the git process.
> > >
> > > complete seconds RAM
> > > 10%   60    900M (includes counting)
> > > 20%   15    900M
> > > 30%   15    900M
> > > 40%   50    1.2G
> > > 50%   80    1.3G
> > > 60%   70    1.7G
> > > 70%   140  1.8G
> > > 80%   180  2.0G
> > > 90%   280  2.2G
> > > 95%   530  2.8G - 1,420 total to here, previous was 1,983
> > > 100% 1390 2.85G
> > > During the writing phase RAM fell to 1.6G
> > > What is being freed in the writing phase??
> >
> > The cached delta results, but you put a cap of 256MB for them.
> >
> > Could you try again with that cache disabled entirely, with
> > pack.deltacachesize = 1 (don't use 0 as that means unbounded).
> >
> > And then, while still keeping the delta cache disabled, could you try
> > with pack.threads = 2, and pack.threads = 1 ?
> >
> > I'm sorry to ask you to do this but I don't have enough ram to even
> > complete a repack with threads=2 so I'm reattempting single threaded at
> > the moment.  But I really wonder if the threading has such an effect on
> > memory usage.
>
> I already have a threads = 1 running with this config. Binary and
> config were same from threads=4 run.
>
> 10% 28min 950M
> 40% 135min 950M
> 50% 157min 900M
> 60% 160min 830M
> 100% 170min 830M
>
> Something is hurting bad with threads. 170 CPU minutes with one
> thread, versus 195 CPU minutes with four threads.
>
> Is there a different memory allocator that can be used when
> multithreaded on gcc? This whole problem may be coming from the memory
> allocation function. git is hardly interacting at all on the thread
> level so it's likely a problem in the C run-time.
>
> [core]
>         repositoryformatversion = 0
>         filemode = true
>         bare = false
>         logallrefupdates = true
> [pack]
>         threads = 1
>         deltacachesize = 256M
>         windowmemory = 256M
>         deltacachelimit = 0
> [remote "origin"]
>         url = git://git.infradead.org/gcc.git
>         fetch = +refs/heads/*:refs/remotes/origin/*
> [branch "trunk"]
>         remote = origin
>         merge = refs/heads/trunk
>
>
>
>
> >
> >
> >
> > >
> > > I have no explanation for the change in RAM usage. Two guesses come to
> > > mind. Memory fragmentation. Or the change in the way the work was
> > > split up altered RAM usage.
> > >
> > > Total CPU time was 195 minutes in 70 minutes clock time. About 70%
> > > efficient. During the compress phase all four cores were active until
> > > the last 90 seconds. Writing the objects took over 23 minutes CPU
> > > bound on one core.
> > >
> > > New pack file is: 270,594,853
> > > Old one was: 344,543,752
> > > It still has 828,660 objects
> >
> > You mean the pack for the gcc repo is now less than 300MB?  Wow.
> >
> >
> > Nicolas
> >
>
>
> --
> Jon Smirl
> jonsmirl@gmail.com
>