Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161769AbbBDScO (ORCPT ); Wed, 4 Feb 2015 13:32:14 -0500 Received: from foss-mx-na.foss.arm.com ([217.140.108.86]:41772 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S967095AbbBDScG (ORCPT ); Wed, 4 Feb 2015 13:32:06 -0500 From: Morten Rasmussen To: peterz@infradead.org, mingo@redhat.com Cc: vincent.guittot@linaro.org, dietmar.eggemann@arm.com, yuyang.du@intel.com, preeti@linux.vnet.ibm.com, mturquette@linaro.org, nico@linaro.org, rjw@rjwysocki.net, juri.lelli@arm.com, linux-kernel@vger.kernel.org Subject: [RFCv3 PATCH 48/48] sched: Disable energy-unfriendly nohz kicks Date: Wed, 4 Feb 2015 18:31:25 +0000 Message-Id: <1423074685-6336-49-git-send-email-morten.rasmussen@arm.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1423074685-6336-1-git-send-email-morten.rasmussen@arm.com> References: <1423074685-6336-1-git-send-email-morten.rasmussen@arm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1770 Lines: 51 With energy-aware scheduling enabled nohz_kick_needed() generates many nohz idle-balance kicks which lead to nothing when multiple tasks get packed on a single cpu to save energy. This causes unnecessary wake-ups and hence wastes energy. Make these conditions depend on !energy_aware() for now until the energy-aware nohz story gets sorted out. cc: Ingo Molnar cc: Peter Zijlstra Signed-off-by: Morten Rasmussen --- kernel/sched/fair.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 1c248f8..cfe65ae 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8195,6 +8195,8 @@ static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) clear_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)); } +static int cpu_overutilized(int cpu, struct sched_domain *sd); + /* * Current heuristic for kicking the idle load balancer in the presence * of an idle cpu in the system. @@ -8234,12 +8236,13 @@ static inline bool nohz_kick_needed(struct rq *rq) if (time_before(now, nohz.next_balance)) return false; - if (rq->nr_running >= 2) + sd = rcu_dereference(rq->sd); + if (rq->nr_running >= 2 && (!energy_aware() || cpu_overutilized(cpu, sd))) return true; rcu_read_lock(); sd = rcu_dereference(per_cpu(sd_busy, cpu)); - if (sd) { + if (sd && !energy_aware()) { sgc = sd->groups->sgc; nr_busy = atomic_read(&sgc->nr_busy_cpus); -- 1.9.1 -- 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/