From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752111AbaALSm6 (ORCPT ); Sun, 12 Jan 2014 13:42:58 -0500 Received: from terminus.zytor.com ([198.137.202.10]:46189 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751548AbaALSmy (ORCPT ); Sun, 12 Jan 2014 13:42:54 -0500 Date: Sun, 12 Jan 2014 10:42:17 -0800 From: tip-bot for Rik van Riel Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, peterz@infradead.org, thellstrom@vmware.com, riel@redhat.com, mgorman@suse.de, tglx@linutronix.de Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, peterz@infradead.org, thellstrom@vmware.com, riel@redhat.com, mgorman@suse.de, tglx@linutronix.de In-Reply-To: <20140106113912.GC6178@suse.de> References: <20140106113912.GC6178@suse.de> To: linux-tip-commits@vger.kernel.org Subject: [tip:sched/urgent] sched: Calculate effective load even if local weight is 0 Git-Commit-ID: 9722c2dac708e9468cc0dc30218ef76946ffbc9d X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.1 (terminus.zytor.com [127.0.0.1]); Sun, 12 Jan 2014 10:42:24 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 9722c2dac708e9468cc0dc30218ef76946ffbc9d Gitweb: http://git.kernel.org/tip/9722c2dac708e9468cc0dc30218ef76946ffbc9d Author: Rik van Riel AuthorDate: Mon, 6 Jan 2014 11:39:12 +0000 Committer: Ingo Molnar CommitDate: Sun, 12 Jan 2014 09:22:15 +0100 sched: Calculate effective load even if local weight is 0 Thomas Hellstrom bisected a regression where erratic 3D performance is experienced on virtual machines as measured by glxgears. It identified commit 58d081b5 ("sched/numa: Avoid overloading CPUs on a preferred NUMA node") as the problem which had modified the behaviour of effective_load. Effective load calculates the difference to the system-wide load if a scheduling entity was moved to another CPU. The task group is not heavier as a result of the move but overall system load can increase/decrease as a result of the change. Commit 58d081b5 ("sched/numa: Avoid overloading CPUs on a preferred NUMA node") changed effective_load to make it suitable for calculating if a particular NUMA node was compute overloaded. To reduce the cost of the function, it assumed that a current sched entity weight of 0 was uninteresting but that is not the case. wake_affine() uses a weight of 0 for sync wakeups on the grounds that it is assuming the waking task will sleep and not contribute to load in the near future. In this case, we still want to calculate the effective load of the sched entity hierarchy. As effective_load is no longer used by task_numa_compare since commit fb13c7ee (sched/numa: Use a system-wide search to find swap/migration candidates), this patch simply restores the historical behaviour. Reported-and-tested-by: Thomas Hellstrom Signed-off-by: Rik van Riel [ Wrote changelog] Signed-off-by: Mel Gorman Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20140106113912.GC6178@suse.de Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index c7395d9..e64b079 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3923,7 +3923,7 @@ static long effective_load(struct task_group *tg, int cpu, long wl, long wg) { struct sched_entity *se = tg->se[cpu]; - if (!tg->parent || !wl) /* the trivial, non-cgroup case */ + if (!tg->parent) /* the trivial, non-cgroup case */ return wl; for_each_sched_entity(se) {