Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755662AbYKJS36 (ORCPT ); Mon, 10 Nov 2008 13:29:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755713AbYKJS3r (ORCPT ); Mon, 10 Nov 2008 13:29:47 -0500 Received: from E23SMTP02.au.ibm.com ([202.81.18.163]:48641 "EHLO e23smtp02.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755666AbYKJS3p (ORCPT ); Mon, 10 Nov 2008 13:29:45 -0500 From: Vaidyanathan Srinivasan Subject: [RFC PATCH v3 3/5] sched: nominate preferred wakeup cpu To: Linux Kernel , Suresh B Siddha , Venkatesh Pallipadi , Peter Zijlstra Cc: Ingo Molnar , Dipankar Sarma , Balbir Singh , Vatsa , Gautham R Shenoy , Andi Kleen , David Collier-Brown , Tim Connors , Max Krasnyansky , Vaidyanathan Srinivasan Date: Tue, 11 Nov 2008 00:03:26 +0530 Message-ID: <20081110183326.562.37718.stgit@drishya.in.ibm.com> In-Reply-To: <20081110181526.562.69941.stgit@drishya.in.ibm.com> References: <20081110181526.562.69941.stgit@drishya.in.ibm.com> User-Agent: StGIT/0.14.2 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3681 Lines: 114 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. For now lets try with a per-cpu variable pointing to a common storage in partition sched domain attribute. Global variable may not work in partitioned sched domain case. Signed-off-by: Vaidyanathan Srinivasan --- include/linux/sched.h | 1 + kernel/sched.c | 34 +++++++++++++++++++++++++++++++++- 2 files changed, 34 insertions(+), 1 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 715028a..8363d02 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -810,6 +810,7 @@ enum sched_domain_level { struct sched_domain_attr { int relax_domain_level; + unsigned int preferred_wakeup_cpu; }; #define SD_ATTR_INIT (struct sched_domain_attr) { \ diff --git a/kernel/sched.c b/kernel/sched.c index d910496..16c5e1f 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -1612,6 +1612,21 @@ static void cfs_rq_set_shares(struct cfs_rq *cfs_rq, unsigned long shares) } #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). + */ + +DEFINE_PER_CPU(unsigned int *, sched_mc_preferred_wakeup_cpu); + +/* Default storage allocation for non-partitioned sched domains */ +unsigned int fallback_preferred_wakeup_cpu; + +#endif + #include "sched_stats.h" #include "sched_idletask.c" #include "sched_fair.c" @@ -3078,6 +3093,7 @@ 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 @@ -3394,6 +3410,10 @@ out_balanced: if (this == group_leader && group_leader != group_min) { *imbalance = min_load_per_task; + if (sched_mc_power_savings >= POWERSAVINGS_BALANCE_WAKEUP) + *per_cpu(sched_mc_preferred_wakeup_cpu, + smp_processor_id()) = + first_cpu(group_leader->cpumask); return group_min; } #endif @@ -7372,7 +7392,7 @@ static void set_domain_attribute(struct sched_domain *sd, static int __build_sched_domains(const cpumask_t *cpu_map, struct sched_domain_attr *attr) { - int i; + int i, cpu; struct root_domain *rd; SCHED_CPUMASK_DECLARE(allmasks); cpumask_t *tmpmask; @@ -7472,6 +7492,18 @@ static int __build_sched_domains(const cpumask_t *cpu_map, sd->parent = p; p->child = sd; cpu_to_core_group(i, cpu_map, &sd->groups, tmpmask); + /* Set the preferred wake up CPU */ + if (attr) { + for_each_cpu_mask_nr(cpu, sd->span) { + per_cpu(sched_mc_preferred_wakeup_cpu, cpu) = + &attr->preferred_wakeup_cpu; + } + } else { + for_each_cpu_mask_nr(cpu, sd->span) { + per_cpu(sched_mc_preferred_wakeup_cpu, cpu) = + &fallback_preferred_wakeup_cpu; + } + } #endif #ifdef CONFIG_SCHED_SMT -- 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/