Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752505AbYKXGK6 (ORCPT ); Mon, 24 Nov 2008 01:10:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750890AbYKXGKu (ORCPT ); Mon, 24 Nov 2008 01:10:50 -0500 Received: from e28smtp07.in.ibm.com ([59.145.155.7]:48842 "EHLO e28smtp07.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750733AbYKXGKt (ORCPT ); Mon, 24 Nov 2008 01:10:49 -0500 Date: Mon, 24 Nov 2008 11:44:31 +0530 From: Vaidyanathan Srinivasan To: Peter Zijlstra Cc: Linux Kernel , Suresh B Siddha , Venkatesh Pallipadi , Ingo Molnar , Dipankar Sarma , Balbir Singh , Vatsa , Gautham R Shenoy , Andi Kleen , David Collier-Brown , Tim Connors , Max Krasnyansky , Gregory Haskins Subject: Re: [RFC PATCH v4 3/7] sched: nominate preferred wakeup cpu Message-ID: <20081124061431.GB4457@dirshya.in.ibm.com> Reply-To: svaidy@linux.vnet.ibm.com Mail-Followup-To: Peter Zijlstra , Linux Kernel , Suresh B Siddha , Venkatesh Pallipadi , Ingo Molnar , Dipankar Sarma , Balbir Singh , Vatsa , Gautham R Shenoy , Andi Kleen , David Collier-Brown , Tim Connors , Max Krasnyansky , Gregory Haskins References: <20081121082533.27075.12056.stgit@drishya.in.ibm.com> <20081121083114.27075.2113.stgit@drishya.in.ibm.com> <1227405838.7685.20000.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1227405838.7685.20000.camel@twins> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2852 Lines: 83 * Peter Zijlstra [2008-11-23 03:03:58]: > On Fri, 2008-11-21 at 14:01 +0530, Vaidyanathan Srinivasan wrote: > > When the system utilisation is low and more cpus are idle, > > then the process waking up from sleep should prefer to > > wakeup an idle cpu from semi-idle cpu package (multi core > > package) rather than a completely idle cpu package which > > would waste power. > > > > Use the sched_mc balance logic in find_busiest_group() to > > nominate a preferred wakeup cpu. > > > > This info can be sored in appropriate sched_domain, but > > updating this info in all copies of sched_domain is not > > practical. Hence this information is stored in root_domain > > struct which is one copy per partitioned sched domain. > > The root_domain can be accessed from each cpu's runqueue > > and there is one copy per partitioned sched domain. > > > > Signed-off-by: Vaidyanathan Srinivasan > > --- > > > > kernel/sched.c | 15 +++++++++++++++ > > 1 files changed, 15 insertions(+), 0 deletions(-) > > > > diff --git a/kernel/sched.c b/kernel/sched.c > > index 79b71f3..d28cd98 100644 > > --- a/kernel/sched.c > > +++ b/kernel/sched.c > > @@ -493,6 +493,17 @@ struct root_domain { > > #ifdef CONFIG_SMP > > struct cpupri cpupri; > > #endif > > +#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) > > + > > + /* > > + * Preferred wake up cpu nominated by sched_mc balance that will be > > + * used when most cpus are idle in the system indicating overall very > > + * low system utilisation. Triggered at POWERSAVINGS_BALANCE_WAKEUP(2) > > + */ > > + unsigned int sched_mc_preferred_wakeup_cpu; > > + > > +#endif > > + > > }; > > > > /* > > Do we really need that extra whitespace? > > > @@ -3090,6 +3101,7 @@ static int move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest, > > return 0; > > } > > > > + > > /* > > * find_busiest_group finds and returns the busiest CPU group within the > > * domain. It calculates and returns the amount of weighted load which > > Ditto? > > > @@ -3406,6 +3418,9 @@ out_balanced: > > > > if (this == group_leader && group_leader != group_min) { > > *imbalance = min_load_per_task; > > + if (sched_mc_power_savings >= POWERSAVINGS_BALANCE_WAKEUP) > > + cpu_rq(this_cpu)->rd->sched_mc_preferred_wakeup_cpu = > > + first_cpu(group_leader->cpumask); > > While not strictly needed, I prefer braces around multi-line statments. > It's easier on the eyes. Hi Peter, Thanks for the detailed review. I will fix these issues in the next iteration. --Vaidy -- 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/