Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755439AbaBUUqR (ORCPT ); Fri, 21 Feb 2014 15:46:17 -0500 Received: from hqemgate15.nvidia.com ([216.228.121.64]:5880 "EHLO hqemgate15.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753159AbaBUUqQ (ORCPT ); Fri, 21 Feb 2014 15:46:16 -0500 X-PGP-Universal: processed; by hqnvupgp08.nvidia.com on Fri, 21 Feb 2014 12:43:53 -0800 Message-ID: <5307BA97.5080809@nvidia.com> Date: Fri, 21 Feb 2014 12:44:07 -0800 From: Sai User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 MIME-Version: 1.0 To: "linux-kernel@vger.kernel.org" CC: "peterz@infradead.org" , "mingo@redhat.com" , , , Subject: Re: [RFC PATCH] sched: Update cpu_load before nohz ilb References: <53067C82.4080807@nvidia.com> In-Reply-To: <53067C82.4080807@nvidia.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org + More people. On 02/20/2014 02:06 PM, Sai wrote: > Update the cpu_load of the kickee in run_rebalance_domains before > calling rebalance_domains if the kickee is in nohz_idle. This avoids > using stale cpu_load for the subsequent load_balance. > > cpu_load in the nohz path is updated on tick_nohz_idle_exit or if a > kickee performances balancing on the behalf of tickless cpus in > nohz_idle_balance. However, the kickee's cpu_load is never updated if it > doesn't exit nohz_idle. This causes stale cpu_load to be used which > causes incorrect load balancing decisions. > > Tested on k3.10. > > Signed-off-by: Sai Gurrappadi > --- > kernel/sched/fair.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > index 860a152..1d4eb4a 100644 > --- a/kernel/sched/fair.c > +++ b/kernel/sched/fair.c > @@ -7140,6 +7140,13 @@ static void run_rebalance_domains(struct > softirq_action *h) > enum cpu_idle_type idle = this_rq->idle_balance ? > CPU_IDLE : CPU_NOT_IDLE; > > + if (test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_rq->cpu))) { > + raw_spin_lock_irq(&this_rq->lock); > + update_rq_clock(this_rq); > + update_idle_cpu_load(this_rq); > + raw_spin_unlock_irq(&this_rq->lock); > + } > + > rebalance_domains(this_rq, idle); > > /* > -- 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/