From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936308AbcLMRYP (ORCPT ); Tue, 13 Dec 2016 12:24:15 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:57068 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936111AbcLMRQ2 (ORCPT ); Tue, 13 Dec 2016 12:16:28 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Michael Kerrisk , Mike Galbraith , Linus Torvalds , Peter Zijlstra , Peter Zijlstra , Thomas Gleixner , linux-man , Ingo Molnar Subject: [PATCH 4.8 13/33] sched/autogroup: Fix 64-bit kernel nice level adjustment Date: Tue, 13 Dec 2016 09:16:14 -0800 Message-Id: <20161213171534.730737756@linuxfoundation.org> X-Mailer: git-send-email 2.10.2 In-Reply-To: <20161213171534.171564506@linuxfoundation.org> References: <20161213171534.171564506@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mike Galbraith commit 83929cce95251cc77e5659bf493bd424ae0e7a67 upstream. Michael Kerrisk reported: > Regarding the previous paragraph... My tests indicate > that writing *any* value to the autogroup [nice priority level] > file causes the task group to get a lower priority. Because autogroup didn't call the then meaningless scale_load()... Autogroup nice level adjustment has been broken ever since load resolution was increased for 64-bit kernels. Use scale_load() to scale group weight. Michael Kerrisk tested this patch to fix the problem: > Applied and tested against 4.9-rc6 on an Intel u7 (4 cores). > Test setup: > > Terminal window 1: running 40 CPU burner jobs > Terminal window 2: running 40 CPU burner jobs > Terminal window 1: running 1 CPU burner job > > Demonstrated that: > * Writing "0" to the autogroup file for TW1 now causes no change > to the rate at which the process on the terminal consume CPU. > * Writing -20 to the autogroup file for TW1 caused those processes > to get the lion's share of CPU while TW2 TW3 get a tiny amount. > * Writing -20 to the autogroup files for TW1 and TW3 allowed the > process on TW3 to get as much CPU as it was getting as when > the autogroup nice values for both terminals were 0. Reported-by: Michael Kerrisk Tested-by: Michael Kerrisk Signed-off-by: Mike Galbraith Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-man Link: http://lkml.kernel.org/r/1479897217.4306.6.camel@gmx.de Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- kernel/sched/auto_group.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/kernel/sched/auto_group.c +++ b/kernel/sched/auto_group.c @@ -192,6 +192,7 @@ int proc_sched_autogroup_set_nice(struct { static unsigned long next = INITIAL_JIFFIES; struct autogroup *ag; + unsigned long shares; int err; if (nice < MIN_NICE || nice > MAX_NICE) @@ -210,9 +211,10 @@ int proc_sched_autogroup_set_nice(struct next = HZ / 10 + jiffies; ag = autogroup_task_get(p); + shares = scale_load(sched_prio_to_weight[nice + 20]); down_write(&ag->lock); - err = sched_group_set_shares(ag->tg, sched_prio_to_weight[nice + 20]); + err = sched_group_set_shares(ag->tg, shares); if (!err) ag->nice = nice; up_write(&ag->lock);