Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759242AbZCYJQl (ORCPT ); Wed, 25 Mar 2009 05:16:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758549AbZCYJO0 (ORCPT ); Wed, 25 Mar 2009 05:14:26 -0400 Received: from e28smtp09.in.ibm.com ([59.145.155.9]:46817 "EHLO e28smtp09.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758584AbZCYJOY (ORCPT ); Wed, 25 Mar 2009 05:14:24 -0400 From: Gautham R Shenoy Subject: [RFC PATCH 08/11] sched: Create a helper function to calculate imbalance. To: "Ingo Molnar" , Peter Zijlstra , "Vaidyanathan Srinivasan" Cc: linux-kernel@vger.kernel.org, Suresh Siddha , "Balbir Singh" , Nick Piggin , "Dhaval Giani" , Bharata B Rao , Gautham R Shenoy Date: Wed, 25 Mar 2009 14:44:12 +0530 Message-ID: <20090325091411.13992.43293.stgit@sofia.in.ibm.com> In-Reply-To: <20090325091239.13992.96090.stgit@sofia.in.ibm.com> References: <20090325091239.13992.96090.stgit@sofia.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: 4622 Lines: 134 Move all the imbalance calculation out of find_busiest_group() through this helper function. With this change, the structure of find_busiest_group() will be as follows: - update_sched_domain_statistics. - Check if imbalance exits. - Update imbalance and return busiest. Signed-off-by: Gautham R Shenoy --- kernel/sched.c | 78 ++++++++++++++++++++++++++++++++------------------------ 1 files changed, 45 insertions(+), 33 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index 364866f..b1b1b8a 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -3383,8 +3383,8 @@ group_next: /** * fix_small_imbalance - Calculate the minor imbalance that exists - * amongst the groups of a sched_domain, during - * load balancing. + * amongst the groups of a sched_domain, during + * load balancing. * @sds: Statistics of the sched_domain whose imbalance is to be calculated. * @this_cpu: The cpu at whose sched_domain we're performing load-balance. * @imbalance: Variable to store the imbalance. @@ -3445,6 +3445,47 @@ static inline void fix_small_imbalance(struct sd_lb_stats *sds, if (pwr_move > pwr_now) *imbalance = sds->busiest_load_per_task; } + +/** + * calculate_imbalance - Calculate the amount of imbalance present within the + * groups of a given sched_domain during load balance. + * @sds: statistics of the sched_domain whose imbalance is to be calculated. + * @this_cpu: Cpu for which currently load balance is being performed. + * @imbalance: The variable to store the imbalance. + */ +static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu, + unsigned long *imbalance) +{ + unsigned long max_pull; + /* + * In the presence of smp nice balancing, certain scenarios can have + * max load less than avg load(as we skip the groups at or below + * its cpu_power, while calculating max_load..) + */ + if (sds->max_load < sds->avg_load) { + *imbalance = 0; + return fix_small_imbalance(sds, this_cpu, imbalance); + } + + /* Don't want to pull so many tasks that a group would go idle */ + max_pull = min(sds->max_load - sds->avg_load, + sds->max_load - sds->busiest_load_per_task); + + /* How much load to actually move to equalise the imbalance */ + *imbalance = min(max_pull * sds->busiest->__cpu_power, + (sds->avg_load - sds->this_load) * sds->this->__cpu_power) + / SCHED_LOAD_SCALE; + + /* + * if *imbalance is less than the average load per runnable task + * there is no gaurantee that any tasks will be moved so we'll have + * a think about bumping its value to force at least one task to be + * moved + */ + if (*imbalance < sds->busiest_load_per_task) + return fix_small_imbalance(sds, this_cpu, imbalance); + +} /******* find_busiest_group() helpers end here *********************/ /* @@ -3458,7 +3499,6 @@ find_busiest_group(struct sched_domain *sd, int this_cpu, int *sd_idle, const struct cpumask *cpus, int *balance) { struct sd_lb_stats sds; - unsigned long max_pull; memset(&sds, 0, sizeof(sds)); @@ -3501,36 +3541,8 @@ find_busiest_group(struct sched_domain *sd, int this_cpu, if (sds.max_load <= sds.busiest_load_per_task) goto out_balanced; - /* - * In the presence of smp nice balancing, certain scenarios can have - * max load less than avg load(as we skip the groups at or below - * its cpu_power, while calculating max_load..) - */ - if (sds.max_load < sds.avg_load) { - *imbalance = 0; - fix_small_imbalance(&sds, this_cpu, imbalance); - goto ret_busiest; - } - - /* Don't want to pull so many tasks that a group would go idle */ - max_pull = min(sds.max_load - sds.avg_load, - sds.max_load - sds.busiest_load_per_task); - - /* How much load to actually move to equalise the imbalance */ - *imbalance = min(max_pull * sds.busiest->__cpu_power, - (sds.avg_load - sds.this_load) * sds.this->__cpu_power) - / SCHED_LOAD_SCALE; - - /* - * if *imbalance is less than the average load per runnable task - * there is no gaurantee that any tasks will be moved so we'll have - * a think about bumping its value to force at least one task to be - * moved - */ - if (*imbalance < sds.busiest_load_per_task) - fix_small_imbalance(&sds, this_cpu, imbalance); - -ret_busiest: + /* Looks like there is an imbalance. Compute it */ + calculate_imbalance(&sds, this_cpu, imbalance); return sds.busiest; out_balanced: -- 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/