Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753234AbZIJSwN (ORCPT ); Thu, 10 Sep 2009 14:52:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753133AbZIJSwM (ORCPT ); Thu, 10 Sep 2009 14:52:12 -0400 Received: from hera.kernel.org ([140.211.167.34]:48104 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753056AbZIJSwL (ORCPT ); Thu, 10 Sep 2009 14:52:11 -0400 Date: Thu, 10 Sep 2009 18:51:37 GMT From: tip-bot for Ingo Molnar Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@redhat.com, a.p.zijlstra@chello.nl, efault@gmx.de, jens.axboe@oracle.com, realnc@arcor.de, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, efault@gmx.de, jens.axboe@oracle.com, realnc@arcor.de, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <4AA93D34.8040500@arcor.de> References: <4AA93D34.8040500@arcor.de> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/core] sched: Disable NEW_FAIR_SLEEPERS for now Message-ID: Git-Commit-ID: 3f2aa307c4d26b4ed6509d0a79e8254c9e07e921 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Thu, 10 Sep 2009 18:51:39 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2823 Lines: 77 Commit-ID: 3f2aa307c4d26b4ed6509d0a79e8254c9e07e921 Gitweb: http://git.kernel.org/tip/3f2aa307c4d26b4ed6509d0a79e8254c9e07e921 Author: Ingo Molnar AuthorDate: Thu, 10 Sep 2009 20:34:48 +0200 Committer: Ingo Molnar CommitDate: Thu, 10 Sep 2009 20:34:48 +0200 sched: Disable NEW_FAIR_SLEEPERS for now Nikos Chantziaras and Jens Axboe reported that turning off NEW_FAIR_SLEEPERS improves desktop interactivity visibly. Nikos described his experiences the following way: " With this setting, I can do "nice -n 19 make -j20" and still have a very smooth desktop and watch a movie at the same time. Various other annoyances (like the "logout/shutdown/restart" dialog of KDE not appearing at all until the background fade-out effect has finished) are also gone. So this seems to be the single most important setting that vastly improves desktop behavior, at least here. " Jens described it the following way, referring to a 10-seconds xmodmap scheduling delay he was trying to debug: " Then I tried switching NO_NEW_FAIR_SLEEPERS on, and then I get: Performance counter stats for 'xmodmap .xmodmap-carl': 9.009137 task-clock-msecs # 0.447 CPUs 18 context-switches # 0.002 M/sec 1 CPU-migrations # 0.000 M/sec 315 page-faults # 0.035 M/sec 0.020167093 seconds time elapsed Woot! " So disable it for now. In perf trace output i can see weird delta timestamps: cc1-9943 [001] 2802.059479616: sched_stat_wait: task: as:9944 wait: 2801938766276 [ns] That nsec field is not supposed to be that large. More digging is needed - but lets turn it off while the real bug is found. Reported-by: Nikos Chantziaras Tested-by: Nikos Chantziaras Reported-by: Jens Axboe Tested-by: Jens Axboe Acked-by: Peter Zijlstra Cc: Mike Galbraith LKML-Reference: <4AA93D34.8040500@arcor.de> Signed-off-by: Ingo Molnar --- kernel/sched_features.h | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/kernel/sched_features.h b/kernel/sched_features.h index 4569bfa..e2dc63a 100644 --- a/kernel/sched_features.h +++ b/kernel/sched_features.h @@ -1,4 +1,4 @@ -SCHED_FEAT(NEW_FAIR_SLEEPERS, 1) +SCHED_FEAT(NEW_FAIR_SLEEPERS, 0) SCHED_FEAT(NORMALIZED_SLEEPER, 0) SCHED_FEAT(ADAPTIVE_GRAN, 1) SCHED_FEAT(WAKEUP_PREEMPT, 1) -- 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/