From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754822Ab2AaPwk (ORCPT ); Tue, 31 Jan 2012 10:52:40 -0500 Received: from e23smtp06.au.ibm.com ([202.81.31.148]:43371 "EHLO e23smtp06.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754510Ab2AaPwi (ORCPT ); Tue, 31 Jan 2012 10:52:38 -0500 Date: Tue, 31 Jan 2012 21:22:28 +0530 From: Kamalesh Babulal To: Diwakar Tundlam Cc: "'Ingo Molnar'" , "'Peter Zijlstra'" , "'linux-kernel@vger.kernel.org'" , Peter De Schrijver , Antti Miettinen , Matthew Longnecker , Kevin Kranzusch Subject: Re: Fix bug: Scheduler's idle-load-balancer not running in first 5 mins after bootup Message-ID: <20120131155228.GB22077@linux.vnet.ibm.com> Reply-To: Kamalesh Babulal References: <1DD7BFEDD3147247B1355BEFEFE466523791832BD5@HQMAIL04.nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1DD7BFEDD3147247B1355BEFEFE466523791832BD5@HQMAIL04.nvidia.com> User-Agent: Mutt/1.5.21 (2010-09-15) x-cbid: 12013105-7014-0000-0000-000000807F71 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Diwakar Tundlam [2012-01-30 10:14:23]: > We ran into this at Nvidia. QA filed a bug saying coremark_4pthreads scores lower (as if running on 3 cores) when run shortly after bootup. But later its score increases to expected values on 4 cores. > > This patch is relevant to linux-2.6.39 but I noticed this fix is not made in linux-3.0, 3.1, 3.2 or 3.3 also. > > Please see commit log for more details of the problem and fix. > > Thanks, > Diwakar. > Tegra Android Kernel SW Engg. > NVIDIA. > Santa Clara, CA > > commit d04d7ef0e3f8c70bd6cd5abb2abc0236aa8d1f7c > Author: Diwakar Tundlam > Date: Wed Jan 18 18:58:57 2012 -0800 > > scheduler: domain: init next_balance in nohz_idle_balancer with jiffies > > The next_balance parameter of nohz_idle_balancer should be initialized > to jiffies since jiffies itself is initialized to 300 seconds shy of > overflow. Otherwise, nohz_idle_balancer does not run for the first 5 > mins after bootup. > > Signed-off-by: Diwakar Tundlam > Reviewed-by: Aleksandr Frid > Reviewed-by: Peter Boonstoppel > Reviewed-by: Satya Popuri > > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/kernel/sched.c b/kernel/sched.c index c5b09f7..506c5da 100644 > --- a/kernel/sched.c > +++ b/kernel/sched.c Can you rebase the patch against tip. kernel/sched* has been moved to kernel/sched/. > @@ -8288,6 +8288,7 @@ void __init sched_init(void) > atomic_set(&nohz.load_balancer, nr_cpu_ids); > atomic_set(&nohz.first_pick_cpu, nr_cpu_ids); > atomic_set(&nohz.second_pick_cpu, nr_cpu_ids); above lines are removed by 0b005cf54eac > + nohz.next_balance = jiffies; > #endif > /* May be allocated at isolcpus cmdline parse time */ > if (cpu_isolated_map == NULL) > -- > 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/ >