From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764531AbZAQQMu (ORCPT ); Sat, 17 Jan 2009 11:12:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761813AbZAQQMi (ORCPT ); Sat, 17 Jan 2009 11:12:38 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:59150 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762361AbZAQQMe (ORCPT ); Sat, 17 Jan 2009 11:12:34 -0500 Date: Sat, 17 Jan 2009 17:12:22 +0100 From: Ingo Molnar To: Mike Galbraith Cc: Andrew Morton , Peter Zijlstra , Linus Torvalds , LKML Subject: Re: [git pull] scheduler fixes Message-ID: <20090117161222.GC31601@elte.hu> References: <20090111144305.GA7154@elte.hu> <20090114121521.197dfc5e.akpm@linux-foundation.org> <1231964647.14825.59.camel@laptop> <20090116204049.f4d6ef1c.akpm@linux-foundation.org> <1232173776.7073.21.camel@marge.simson.net> <1232186054.6813.48.camel@marge.simson.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1232186054.6813.48.camel@marge.simson.net> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Mike Galbraith wrote: > Dunno about the IO bits, but.. > > The problem with the C++ testcases seems to be wake_up_all() plunking a > genuine thundering herd onto runqueues. The sleeper fairness logic > places the entire herd left of min_vruntime, meaning N*sched_latency > pain for the poor sods who are setting the runqueue pace. 100 wakeup pairs that all run and ping-pong between each other? That creates 200 tasks with an average system load of 100.0, on a dual-core system. Is that a fair representation of some real workload, or just an unrealistic "gee, look, given enough tasks running I can overload the system _this bad_" example? Ingo