From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jon Smirl" Subject: Re: Git and GCC Date: Thu, 6 Dec 2007 17:22:04 -0500 Message-ID: <9e4733910712061422w139273c0gf3cfb04c6ba8c509@mail.gmail.com> References: <4aca3dc20712051947t5fbbb383ua1727c652eb25d7e@mail.gmail.com> <9e4733910712052247x116cabb4q48ebafffb93f7e03@mail.gmail.com> <20071206071503.GA19504@coredump.intra.peff.net> <20071206173946.GA10845@sigill.intra.peff.net> <9e4733910712061055p353775d8wd0321bc9c81297b7@mail.gmail.com> <9e4733910712061339n3aef023r22e5b73aac120c8a@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "Linus Torvalds" , "Jeff King" , "Daniel Berlin" , "Harvey Harrison" , "David Miller" , ismail@pardus.org.tr, gcc@gcc.gnu.org, git@vger.kernel.org To: "Nicolas Pitre" X-From: gcc-return-142775-gcc=m.gmane.org@gcc.gnu.org Thu Dec 06 23:22:32 2007 Return-path: Envelope-to: gcc@gmane.org Received: from sourceware.org ([209.132.176.174]) by lo.gmane.org with smtp (Exim 4.50) id 1J0P71-0002u3-2s for gcc@gmane.org; Thu, 06 Dec 2007 23:22:31 +0100 Received: (qmail 19873 invoked by alias); 6 Dec 2007 22:22:13 -0000 Received: (qmail 19861 invoked by uid 22791); 6 Dec 2007 22:22:12 -0000 X-Spam-Check-By: sourceware.org Received: from wa-out-1112.google.com (HELO wa-out-1112.google.com) (209.85.146.178) by sourceware.org (qpsmtpd/0.31) with ESMTP; Thu, 06 Dec 2007 22:22:06 +0000 Received: by wa-out-1112.google.com with SMTP id m16so872360waf for ; Thu, 06 Dec 2007 14:22:04 -0800 (PST) Received: by 10.114.73.1 with SMTP id v1mr1457271waa.1196979724791; Thu, 06 Dec 2007 14:22:04 -0800 (PST) Received: by 10.114.208.17 with HTTP; Thu, 6 Dec 2007 14:22:04 -0800 (PST) In-Reply-To: Content-Disposition: inline Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Delivered-To: mailing list gcc@gcc.gnu.org Archived-At: On 12/6/07, Nicolas Pitre wrote: > On Thu, 6 Dec 2007, Jon Smirl wrote: > > > On 12/6/07, Nicolas Pitre wrote: > > > > When I lasted looked at the code, the problem was in evenly dividing > > > > the work. I was using a four core machine and most of the time one > > > > core would end up with 3-5x the work of the lightest loaded core. > > > > Setting pack.threads up to 20 fixed the problem. With a high number of > > > > threads I was able to get a 4hr pack to finished in something like > > > > 1:15. > > > > > > But as far as I know you didn't try my latest incarnation which has been > > > available in Git's master branch for a few months already. > > > > I've deleted all my giant packs. Using the kernel pack: > > 4GB Q6600 > > > > Using the current thread pack code I get these results. > > > > The interesting case is the last one. I set it to 15 threads and > > monitored with 'top'. > > For 0-60% compression I was at 300% CPU, 60-74% was 200% CPU and > > 74-100% was 100% CPU. It never used all for cores. The only other > > things running were top and my desktop. This is the same load > > balancing problem I observed earlier. > > Well, that's possible with a window 25 times larger than the default. Why did it never use more than three cores? > > The load balancing is solved with a master thread serving relatively > small object list segments to any work thread that finished with its > previous segment. But the size for those segments is currently fixed to > window * 1000 which is way too large when window == 250. > > I have to find a way to auto-tune that segment size somehow. > > But with the default window size there should not be any such noticeable > load balancing problem. > > Note that threading only happens in the compression phase. The count > and write phase are hardly paralleled. > > > Nicolas > -- Jon Smirl jonsmirl@gmail.com