From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756582Ab0CKJ6u (ORCPT ); Thu, 11 Mar 2010 04:58:50 -0500 Received: from mail.gmx.net ([213.165.64.20]:57541 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1755746Ab0CKJ6s (ORCPT ); Thu, 11 Mar 2010 04:58:48 -0500 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX1+m7C4bLT2mdOSW1OJFV0ZAnXwDsSFTH9ysiHTXv9 mG2BXmFMcZtpp6 Subject: Re: [patch 8/12] sched: remove FAIR_SLEEPERS feature From: Mike Galbraith To: Peter Zijlstra Cc: Ingo Molnar , LKML In-Reply-To: <1268300950.6785.27.camel@marge.simson.net> References: <1268300950.6785.27.camel@marge.simson.net> Content-Type: text/plain Date: Thu, 11 Mar 2010 10:58:40 +0100 Message-Id: <1268301520.6785.40.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1.1 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 X-FuHaFi: 0.52000000000000002 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org sched: remove FAIR_SLEEPERS feature Our preemption model relies too heavily on sleeper fairness to disable it without dire consequences. Remove the feature, and save a branch or two. Signed-off-by: Mike Galbraith Cc: Ingo Molnar Cc: Peter Zijlstra LKML-Reference: --- kernel/sched_fair.c | 2 +- kernel/sched_features.h | 7 ------- 2 files changed, 1 insertion(+), 8 deletions(-) Index: linux-2.6/kernel/sched_fair.c =================================================================== --- linux-2.6.orig/kernel/sched_fair.c +++ linux-2.6/kernel/sched_fair.c @@ -737,7 +737,7 @@ place_entity(struct cfs_rq *cfs_rq, stru vruntime += sched_vslice(cfs_rq, se); /* sleeps up to a single latency don't count. */ - if (!initial && sched_feat(FAIR_SLEEPERS)) { + if (!initial) { unsigned long thresh = sysctl_sched_latency; /* Index: linux-2.6/kernel/sched_features.h =================================================================== --- linux-2.6.orig/kernel/sched_features.h +++ linux-2.6/kernel/sched_features.h @@ -1,11 +1,4 @@ /* - * 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, 1) - -/* * Only give sleepers 50% of their service deficit. This allows * them to run sooner, but does not allow tons of sleepers to * rip the spread apart.