Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750773AbWEZOVk (ORCPT ); Fri, 26 May 2006 10:21:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750780AbWEZOVk (ORCPT ); Fri, 26 May 2006 10:21:40 -0400 Received: from mail.gmx.de ([213.165.64.20]:63423 "HELO mail.gmx.net") by vger.kernel.org with SMTP id S1750773AbWEZOVj (ORCPT ); Fri, 26 May 2006 10:21:39 -0400 X-Authenticated: #14349625 Subject: Re: [RFC 3/5] sched: Add CPU rate hard caps From: Mike Galbraith To: Peter Williams Cc: Con Kolivas , Linux Kernel , Kingsley Cheung , Ingo Molnar , Rene Herman In-Reply-To: <447709B3.80309@bigpond.net.au> References: <20060526042021.2886.4957.sendpatchset@heathwren.pw.nest> <20060526042051.2886.70594.sendpatchset@heathwren.pw.nest> <200605262100.22071.kernel@kolivas.org> <447709B3.80309@bigpond.net.au> Content-Type: text/plain Date: Fri, 26 May 2006 16:23:18 +0200 Message-Id: <1148653398.8321.7.camel@homer> Mime-Version: 1.0 X-Mailer: Evolution 2.4.0 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1434 Lines: 34 On Fri, 2006-05-26 at 23:59 +1000, Peter Williams wrote: > Con Kolivas wrote: > > On Friday 26 May 2006 14:20, Peter Williams wrote: > >> This patch implements hard CPU rate caps per task as a proportion of a > >> single CPU's capacity expressed in parts per thousand. > > > > A hard cap of 1/1000 could lead to interesting starvation scenarios where a > > mutex or semaphore was held by a task that hardly ever got cpu. Same goes to > > a lesser extent to a 0 soft cap. > > > > Here is how I handle idleprio tasks in current -ck: > > > > http://ck.kolivas.org/patches/2.6/pre-releases/2.6.17-rc5/2.6.17-rc5-ck1/patches/track_mutexes-1.patch > > tags tasks that are holding a mutex > > > > http://ck.kolivas.org/patches/2.6/pre-releases/2.6.17-rc5/2.6.17-rc5-ck1/patches/sched-idleprio-1.7.patch > > is the idleprio policy for staircase. > > > > What it does is runs idleprio tasks as normal tasks when they hold a mutex or > > are waking up after calling down() (ie holding a semaphore). > > I wasn't aware that you could detect those conditions. They could be > very useful. Isn't this exactly what the PI code is there to handle? Is something more than PI needed? -Mike - 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/