From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rik van Riel Subject: [RFC -v7 PATCH 1/7] sched: check the right ->nr_running in yield_task_fair Date: Wed, 26 Jan 2011 17:19:50 -0500 Message-ID: <20110126171950.5668f082@annuminas.surriel.com> References: <20110126165657.2ddd2ac9@annuminas.surriel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, Avi Kiviti , Srivatsa Vaddagiri , Peter Zijlstra , Mike Galbraith , Chris Wright , ttracy@redhat.com, "Nakajima, Jun" To: kvm@vger.kernel.org Return-path: In-Reply-To: <20110126165657.2ddd2ac9@annuminas.surriel.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org With CONFIG_FAIR_GROUP_SCHED, each task_group has its own cfs_rq. Yielding to a task from another cfs_rq may be worthwhile, since a process calling yield typically cannot use the CPU right now. Therefor, we want to check the per-cpu nr_running, not the cgroup local one. Signed-off-by: Rik van Riel --- kernel/sched_fair.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index c62ebae..7b338ac 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1304,7 +1304,7 @@ static void yield_task_fair(struct rq *rq) /* * Are we the only task in the tree? */ - if (unlikely(cfs_rq->nr_running == 1)) + if (unlikely(rq->nr_running == 1)) return; clear_buddies(cfs_rq, se);