Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757011Ab2EVJGR (ORCPT ); Tue, 22 May 2012 05:06:17 -0400 Received: from mailout-de.gmx.net ([213.165.64.22]:41100 "HELO mailout-de.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1755965Ab2EVJGO (ORCPT ); Tue, 22 May 2012 05:06:14 -0400 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX19TT/oFs51TF+oQqOvpXzLkXyuRG23ByAjbTmAI6C Wmxx7dv4zBsZ1i Message-ID: <1337677564.5446.11.camel@marge.simpson.net> Subject: Re: [PATCH 1/2] sched: readd FAIR_SLEEPERS feature From: Mike Galbraith To: Christian Ehrhardt Cc: Martin Schwidefsky , Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, Heiko Carstens Date: Tue, 22 May 2012 11:06:04 +0200 In-Reply-To: <4FBB3C3B.3090202@linux.vnet.ibm.com> References: <1337615137-55111-1-git-send-email-schwidefsky@de.ibm.com> <1337615137-55111-2-git-send-email-schwidefsky@de.ibm.com> <4FBB3C3B.3090202@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1507 Lines: 43 On Tue, 2012-05-22 at 09:11 +0200, Christian Ehrhardt wrote: > > On 05/21/2012 05:45 PM, Martin Schwidefsky wrote: > [...] > > --- a/kernel/sched/features.h > > +++ b/kernel/sched/features.h > > @@ -1,3 +1,12 @@ > > +#ifdef CONFIG_SCHED_FAIR_SLEEPERS > > +/* > > + * Disregards a certain amount of sleep time (sched_latency_ns) and > > + * considers the task to be running during that period. This gives it > > + * a service deficit on wakeup, allowing it to run sooner. > > + */ > > +SCHED_FEAT(FAIR_SLEEPERS, false) > > +#endif > > + > > /* > > * Only give sleepers 50% of their service deficit. This allows > > * them to run sooner, but does not allow tons of sleepers to > > This would be right for s390, but a change to every other architecture. > As far as I know s390 had custom patches in any distribution supported > on s390 to set the default to false (like in your patch), but the > upstream default for every other architecture was true. > > I think the patch could look like this to make all happy: > ... > +#ifndef CONFIG_S390 > + SCHED_FEAT(FAIR_SLEEPERS, true) > +#else > +SCHED_FEAT(FAIR_SLEEPERS, false) > ... Um, yeah, default off is a non-starter.. until someone comes up with a less annoying preemption model that is. -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/