Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755959Ab3DWI2j (ORCPT ); Tue, 23 Apr 2013 04:28:39 -0400 Received: from LGEMRELSE1Q.lge.com ([156.147.1.111]:53936 "EHLO LGEMRELSE1Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755352Ab3DWI1t (ORCPT ); Tue, 23 Apr 2013 04:27:49 -0400 X-AuditID: 9c93016f-b7c5fae00000791a-90-517646008ff1 From: Joonsoo Kim To: Ingo Molnar , Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Srivatsa Vaddagiri , Davidlohr Bueso , Jason Low , Joonsoo Kim Subject: [PATCH v3 4/6] sched: move up affinity check to mitigate useless redoing overhead Date: Tue, 23 Apr 2013 17:27:40 +0900 Message-Id: <1366705662-3587-5-git-send-email-iamjoonsoo.kim@lge.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1366705662-3587-1-git-send-email-iamjoonsoo.kim@lge.com> References: <1366705662-3587-1-git-send-email-iamjoonsoo.kim@lge.com> X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2477 Lines: 75 Currently, LBF_ALL_PINNED is cleared after affinity check is passed. So, if task migration is skipped by small load value or small imbalance value in move_tasks(), we don't clear LBF_ALL_PINNED. At last, we trigger 'redo' in load_balance(). Imbalance value is often so small that any tasks cannot be moved to other cpus and, of course, this situation may be continued after we change the target cpu. So this patch move up affinity check code and clear LBF_ALL_PINNED before evaluating load value in order to mitigate useless redoing overhead. In addition, re-order some comments correctly. Acked-by: Peter Zijlstra Tested-by: Jason Low Signed-off-by: Joonsoo Kim diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index dfa92b7..b8ef321 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3896,10 +3896,14 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env) int tsk_cache_hot = 0; /* * We do not migrate tasks that are: - * 1) running (obviously), or + * 1) throttled_lb_pair, or * 2) cannot be migrated to this CPU due to cpus_allowed, or - * 3) are cache-hot on their current CPU. + * 3) running (obviously), or + * 4) are cache-hot on their current CPU. */ + if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu)) + return 0; + if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) { int new_dst_cpu; @@ -3967,9 +3971,6 @@ static int move_one_task(struct lb_env *env) struct task_struct *p, *n; list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) { - if (throttled_lb_pair(task_group(p), env->src_rq->cpu, env->dst_cpu)) - continue; - if (!can_migrate_task(p, env)) continue; @@ -4021,7 +4022,7 @@ static int move_tasks(struct lb_env *env) break; } - if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu)) + if (!can_migrate_task(p, env)) goto next; load = task_h_load(p); @@ -4032,9 +4033,6 @@ static int move_tasks(struct lb_env *env) if ((load / 2) > env->imbalance) goto next; - if (!can_migrate_task(p, env)) - goto next; - move_task(p, env); pulled++; env->imbalance -= load; -- 1.7.9.5 -- 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/