Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751451AbWE0J02 (ORCPT ); Sat, 27 May 2006 05:26:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751452AbWE0J02 (ORCPT ); Sat, 27 May 2006 05:26:28 -0400 Received: from mail.gmx.net ([213.165.64.21]:39329 "HELO mail.gmx.net") by vger.kernel.org with SMTP id S1751451AbWE0J01 (ORCPT ); Sat, 27 May 2006 05:26:27 -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: <44779A61.7070002@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> <1148653398.8321.7.camel@homer> <44779A61.7070002@bigpond.net.au> Content-Type: text/plain Date: Sat, 27 May 2006 11:28:07 +0200 Message-Id: <1148722087.7578.15.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: 1934 Lines: 43 On Sat, 2006-05-27 at 10:16 +1000, Peter Williams wrote: > Mike Galbraith wrote: > > 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? > > > > AFAIK (but I may be wrong) PI is only used by RT tasks and would need to > be extended. It could be argued that extending PI so that it can be > used by non RT tasks is a worthwhile endeavour in its own right. Hm. Looking around a bit, it appears to me that we're one itty bitty redefine away from PI being global. No idea if/when that will happen though. -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/