Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765123AbYBMFtg (ORCPT ); Wed, 13 Feb 2008 00:49:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752397AbYBMFt2 (ORCPT ); Wed, 13 Feb 2008 00:49:28 -0500 Received: from mail.gmx.net ([213.165.64.20]:34628 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751807AbYBMFt1 (ORCPT ); Wed, 13 Feb 2008 00:49:27 -0500 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX18nNYF9E40nVc3nQn4kHRLEgLVmByDEVi5yvhgcC6 QWCMcw7yEmRFpX Subject: Re: Scheduler(?) regression from 2.6.22 to 2.6.24 for short-lived threads From: Mike Galbraith To: Olof Johansson Cc: Willy Tarreau , linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar In-Reply-To: <1202808206.7829.36.camel@homer.simson.net> References: <1202554705.10287.12.camel@homer.simson.net> <20080209114009.GP8953@1wt.eu> <1202564259.4035.18.camel@homer.simson.net> <20080209161957.GA3364@1wt.eu> <20080210052941.GA4731@lixom.net> <20080210061558.GC22137@1wt.eu> <20080210070056.GA6401@lixom.net> <1202717755.21339.65.camel@homer.simson.net> <20080211172648.GA7962@lixom.net> <1202759926.4165.31.camel@homer.simson.net> <20080211203159.GA11161@lixom.net> <1202808206.7829.36.camel@homer.simson.net> Content-Type: text/plain Date: Wed, 13 Feb 2008 06:49:22 +0100 Message-Id: <1202881762.27877.5.camel@homer.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.12.0 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1392 Lines: 50 On Tue, 2008-02-12 at 10:23 +0100, Mike Galbraith wrote: > If you plunk a usleep(1) in prior to calling thread_func() does your > testcase performance change radically? If so, I wonder if the real > application has the same kind of dependency. The answer is yes for 2.6.22, and no for 2.6.24, which surprised me. 2.6.22.17-smp homer:..local/tmp # ./threadtest2 10000000 loops time 16215 ms 10000000 loops time 16268 ms 10000000 loops time 16246 ms homer:..local/tmp # ./threadtest3 (with usleep(1)) 10000000 loops time 13938 ms 10000000 loops time 13921 ms 10000000 loops time 13898 ms 2.6.24.1-smp homer:..local/tmp # ./threadtest2 10000000 loops time 14663 ms 10000000 loops time 14523 ms 10000000 loops time 14466 ms homer:..local/tmp # ./threadtest3 10000000 loops time 14513 ms 10000000 loops time 14500 ms 10000000 loops time 14464 ms echo 0 > /proc/sys/kernel/sched_child_runs_first homer:..local/tmp # ./threadtest2 10000000 loops time 14157 ms 10000000 loops time 14097 ms 10000000 loops time 14153 ms homer:..local/tmp # ./threadtest3 10000000 loops time 14065 ms 10000000 loops time 14075 ms 10000000 loops time 14018 ms -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/