From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760467Ab2J2UjQ (ORCPT ); Mon, 29 Oct 2012 16:39:16 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:9739 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758282Ab2J2Uiz (ORCPT ); Mon, 29 Oct 2012 16:38:55 -0400 X-Authority-Analysis: v=2.0 cv=KcBQQHkD c=1 sm=0 a=rXTBtCOcEpjy1lPqhTCpEQ==:17 a=mNMOxpOpBa8A:10 a=Ciwy3NGCPMMA:10 a=NwVulMYDqiUA:10 a=5SG0PmZfjMsA:10 a=bbbx4UPp9XUA:10 a=meVymXHHAAAA:8 a=D-9iOUBoPy4A:10 a=pGLkceISAAAA:8 a=VwQbUJbxAAAA:8 a=Z4Rwk6OoAAAA:8 a=20KFwNOVAAAA:8 a=9AzMRrQhAAAA:8 a=NufY4J3AAAAA:8 a=KKAkSRfTAAAA:8 a=JfrnYn6hAAAA:8 a=ftUzEednAAAA:8 a=sozttTNsAAAA:8 a=EUspDBNiAAAA:8 a=VnNF1IyMAAAA:8 a=fh4mg5NFAAAA:8 a=t6nRzRaj4nB9lmydYAEA:9 a=MSl-tDqOz04A:10 a=LI9Vle30uBYA:10 a=jbrJJM5MRmoA:10 a=jEp0ucaQiEUA:10 a=SxxB86fLhQ4A:10 a=re9sYKne76oA:10 a=WwgC8nHKvroA:10 a=3Rfx1nUSh_UA:10 a=QwxQZocgbLcA:10 a=x2szoZtqnggA:10 a=IG2fH9E8heMA:10 a=Im-eZXwrtqoA:10 a=jeBq3FmKZ4MA:10 a=Zh68SRI7RUMA:10 a=rXTBtCOcEpjy1lPqhTCpEQ==:117 X-Cloudmark-Score: 0 X-Originating-IP: 74.67.115.198 Message-Id: <20121029203850.897192220@goodmis.org> User-Agent: quilt/0.60-1 Date: Mon, 29 Oct 2012 16:27:40 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Andrew Morton , Thomas Gleixner , Peter Zijlstra , Clark Williams , Frederic Weisbecker , Li Zefan , Ingo Molnar , "Paul E. McKenney" , Mike Galbraith , Alessio Igor Bogani , Avi Kivity , Chris Metcalf , Christoph Lameter , Daniel Lezcano , Geoff Levand , Gilad Ben Yossef , Hakan Akkan , Kevin Hilman , Max Krasnyansky , Stephen Hemminger , Sven-Thorsten Dietrich Subject: [PATCH 29/32] sched: Update nohz rq clock before searching busiest group on load balancing References: <20121029202711.062749374@goodmis.org> Content-Disposition: inline; filename=0029-sched-Update-nohz-rq-clock-before-searching-busiest-.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Frederic Weisbecker While load balancing an rq target, we look for the busiest group. This operation may require an uptodate rq clock if we end up calling scale_rt_power(). To this end, update it manually if the target is running tickless. DOUBT: don't we actually also need this in vanilla kernel, in case this_cpu is in dyntick-idle mode? Signed-off-by: Frederic Weisbecker Cc: Alessio Igor Bogani Cc: Andrew Morton Cc: Avi Kivity Cc: Chris Metcalf Cc: Christoph Lameter Cc: Daniel Lezcano Cc: Geoff Levand Cc: Gilad Ben Yossef Cc: Hakan Akkan Cc: Ingo Molnar Cc: Kevin Hilman Cc: Max Krasnyansky Cc: Paul E. McKenney Cc: Peter Zijlstra Cc: Stephen Hemminger Cc: Steven Rostedt Cc: Sven-Thorsten Dietrich Cc: Thomas Gleixner --- kernel/sched/fair.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 89e816e..b1b9a20 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4252,6 +4252,19 @@ static int load_balance(int this_cpu, struct rq *this_rq, schedstat_inc(sd, lb_count[idle]); + /* + * find_busiest_group() may need an uptodate cpu clock + * for find_busiest_group() (see scale_rt_power()). If + * the CPU is nohz, it's clock may be stale. + */ + if (cpuset_cpu_adaptive_nohz(this_cpu)) { + local_irq_save(flags); + raw_spin_lock(&this_rq->lock); + update_rq_clock(this_rq); + raw_spin_unlock(&this_rq->lock); + local_irq_restore(flags); + } + redo: group = find_busiest_group(&env, balance); -- 1.7.10.4