From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757462AbYCYQls (ORCPT ); Tue, 25 Mar 2008 12:41:48 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753168AbYCYQlk (ORCPT ); Tue, 25 Mar 2008 12:41:40 -0400 Received: from mu-out-0910.google.com ([209.85.134.185]:43872 "EHLO mu-out-0910.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752790AbYCYQlj (ORCPT ); Tue, 25 Mar 2008 12:41:39 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=message-id:date:from:sender:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references:x-google-sender-auth; b=TtbsBr5Mqk0mvkOW2rIjUdcoCL1OQ6xGdCcDK6TiQYS5MckuptwUJeGe0RX1NeNUNmQgnJBUby6Z4xOTxiwP6r7oMhfgFrTvaDfKg40hsZD2iAoyKiKu6gKe27B61J66t+YyKmljUvU4aq67tFiXlhvkc32K8D+RPV7MyIR/MGo= Message-ID: <2c0942db0803250941j65be093et718bb838a2779e9c@mail.gmail.com> Date: Tue, 25 Mar 2008 09:41:30 -0700 From: "Ray Lee" To: "Sanders, Rob M." Subject: Re: Performance changes between 2.6.13 and 2.6.23 Cc: linux-kernel@vger.kernel.org, bart.vanassche@gmail.com In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: X-Google-Sender-Auth: b4d3a4b436739cd3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 25, 2008 at 5:34 AM, Sanders, Rob M. wrote: > Hello all, > I've been lurking on the digest for some time (don't want to receive full lkml traffic at work) and saw the > posts about Wine performance regressions in 2.6.24. Some of what I saw there, particularly Andi Kleen's > responses, mirror something that I see on my box at home. I had emailed Andi directly since I only read the > digest, and I'm posting this here at his suggestion. Please CC: rms@zai.com with any replies, as I'm only > getting the lkml digest. > I'm running on a dual 2GHZ G5 Powermac w/2GB ram. I recently upgraded from YDL4.0.91 (2.6.13 kernel) to > YDL6 (2.6.23 kernel) and noticed that the overall performance of the box seems more sluggish after the upgrade. > Of more particular concern, the main application that I build has seen a 4-5X slowdown in performance. Under > YDL4.0.91 I could process roughly 1e8 data points in ~2 seconds, and under YDL6.0 I now process 1e8 data points So, two processors, and multiple processes passing data back and forth. Key point seems to be: > in ~8 seconds. Total CPU loading (from top) is about 5%, under both systems. The application spawns multiple > processes and uses semaphores and shared memory to move data between the processes. When I use 'vmstat 3' the > single biggest difference I see between YDL4.0.91 and YDL6 is that the YDL4.0.91 system is the YDL4.0.91 system is > context switching about 7000 per interval, whereas the YDl6 system is context switching about 1200 times per interval. Many more context switches per second, so a lot less work is getting done each time. > I've been talking somewhat with Owen Stampflee (works for the distro maker, TSS) and have rebuilt the kernel on > the 2.6 box removing some of the things that I don't need on my box (cell support, etc). There did seem (subjectively) > to be a slight improvement after that. When I get some more time to play at home I'm going to take the 2.6.13 .config > I use and build a 2.6.23 kernal using 'make oldconfig' and try to figure if it is a config issues. > I realize that going from 2.6.13 to 2.6.23 is a *huge* change, and that the problems may not be tied to the kernel > but to other things, but are there any other suggestions folks have for finding the cause of the performance slowdow A lot has changed between 2.6.23 and current mainline as well. Particularly in the scheduler, which I suspect is the issue for your test. If possible, could you try a 2.6.25-rc-latest kernel, both before and after an "echo 5 > /proc/sys/kernel/sched_features" and see if that makes any difference?