Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752277AbbH1LOf (ORCPT ); Fri, 28 Aug 2015 07:14:35 -0400 Received: from mail-lb0-f172.google.com ([209.85.217.172]:32830 "EHLO mail-lb0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751445AbbH1LOe (ORCPT ); Fri, 28 Aug 2015 07:14:34 -0400 MIME-Version: 1.0 In-Reply-To: <1440694201.32300.72.camel@j-VirtualBox> References: <1438595750-20455-1-git-send-email-vincent.guittot@linaro.org> <1440694201.32300.72.camel@j-VirtualBox> From: Vincent Guittot Date: Fri, 28 Aug 2015 13:14:12 +0200 Message-ID: Subject: Re: [PATCH v2] sched: fix nohz.next_balance update To: Jason Low Cc: Peter Zijlstra , Ingo Molnar , linux-kernel , Preeti U Murthy , Linaro Kernel Mailman List Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1529 Lines: 33 On 27 August 2015 at 18:50, Jason Low wrote: > On Thu, 2015-08-27 at 13:21 +0200, Vincent Guittot wrote: >> Hi, >> >> On 3 August 2015 at 11:55, Vincent Guittot wrote: >> > Since commit d4573c3e1c99 ("sched: Improve load balancing in the presence >> > of idle CPUs"), the ILB CPU starts with the idle load balancing of other >> > idle CPUs and finishes with itself in order to speed up the spread of tasks >> > in all idle CPUs. >> > >> > The this_rq->next_balance is still used in nohz_idle_balance as an >> > intermediate step to gather the shortest next balance before updating >> > nohz.next_balance. But the former has not been updated yet and is likely to >> > be set with the current jiffies. As a result, the nohz.next_balance will be >> > set with current jiffies instead of the real next balance date. This >> > generates spurious kicks of nohz ilde balance. >> > >> > nohz_idle_balance must set the nohz.next_balance without taking into >> > account this_rq->next_balance which is not updated yet. Then, this_rq will >> > update nohz.next_update with its next_balance once updated and if necessary. >> > >> > Signed-off-by: Vincent Guittot > > Acked-by: Jason Low Thanks > -- 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/