Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763035AbYBGVNv (ORCPT ); Thu, 7 Feb 2008 16:13:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755277AbYBGUy1 (ORCPT ); Thu, 7 Feb 2008 15:54:27 -0500 Received: from cantor.suse.de ([195.135.220.2]:46077 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933215AbYBGUyY (ORCPT ); Thu, 7 Feb 2008 15:54:24 -0500 Date: Thu, 7 Feb 2008 12:48:17 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , Michael Krufky , Chuck Ebbert , Domenico Andreoli , torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Ingo Molnar Subject: [patch 41/45] sched: fix high wake up latencies with FAIR_USER_SCHED Message-ID: <20080207204817.GP16389@suse.de> References: <20080207204118.202098927@mini.kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline; filename="sched-fix-high-wake-up-latencies-with-fair_user_sched.patch" In-Reply-To: <20080207204549.GA16389@suse.de> User-Agent: Mutt/1.5.16 (2007-06-09) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1694 Lines: 50 2.6.24-stable review patch. If anyone has any objections, please let us know. ------------------ From: Srivatsa Vaddagiri patch 296825cbe14d4c95ee9c41ca5824f7487bfb4d9d in mainline. The reason why we are getting better wakeup latencies for !FAIR_USER_SCHED is because of this snippet of code in place_entity(): if (!initial) { /* sleeps upto a single latency don't count. */ if (sched_feat(NEW_FAIR_SLEEPERS) && entity_is_task(se)) ^^^^^^^^^^^^^^^^^^ vruntime -= sysctl_sched_latency; /* ensure we never gain time by being placed backwards. */ vruntime = max_vruntime(se->vruntime, vruntime); } NEW_FAIR_SLEEPERS feature gives credit for sleeping only to tasks and not group-level entities. With the patch attached, I could see that wakeup latencies with FAIR_USER_SCHED are restored to the same level as !FAIR_USER_SCHED. Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- kernel/sched_fair.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -511,7 +511,7 @@ place_entity(struct cfs_rq *cfs_rq, stru if (!initial) { /* sleeps upto a single latency don't count. */ - if (sched_feat(NEW_FAIR_SLEEPERS) && entity_is_task(se)) + if (sched_feat(NEW_FAIR_SLEEPERS)) vruntime -= sysctl_sched_latency; /* ensure we never gain time by being placed backwards. */ -- -- 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/