From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751234AbXCKHcu (ORCPT ); Sun, 11 Mar 2007 03:32:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751255AbXCKHcu (ORCPT ); Sun, 11 Mar 2007 03:32:50 -0400 Received: from 1wt.eu ([62.212.114.60]:1118 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751234AbXCKHct (ORCPT ); Sun, 11 Mar 2007 03:32:49 -0400 Date: Sun, 11 Mar 2007 08:32:28 +0100 From: Willy Tarreau To: Matt Mackall Cc: Con Kolivas , linux-kernel , akpm@osdl.org Subject: Re: RSDL-mm 0.28 Message-ID: <20070311073228.GM943@1wt.eu> References: <20070311013506.GD10459@waste.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070311013506.GD10459@waste.org> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Mar 10, 2007 at 07:35:06PM -0600, Matt Mackall wrote: > I've tested -mm2 against -mm2+noyield and -mm2+rsdl+noyield. The > noyield patch simply makes the sched_yield syscall return immediately. > Xorg and all tests are run at nice 0. [skipped long and precise test report] > Also note I could occassionally trigger nasty multi-second pauses with > -mm2+noyield under exectest that didn't show up elsewhere. That's > probably a bug in the mainline scheduler. This is not a bug per se, but more a design problem. This is caused by the interactivity booster which is unfair. Mike Galbraith and others spent a lot of time trying to get rid of those problems a few versions ago. In early kernels (around 2.6.11), I could trivially cause pauses more than 30 seconds long by running a few tasks simulating an interactive workload. It is much more difficult to achieve this with recent kernels, and it has absolutely no effect on RSDL, which is one of the reasons I have to find it great ! Regards, Willy