From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757995Ab3G3Ht5 (ORCPT ); Tue, 30 Jul 2013 03:49:57 -0400 Received: from e38.co.us.ibm.com ([32.97.110.159]:40729 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754575Ab3G3Hty (ORCPT ); Tue, 30 Jul 2013 03:49:54 -0400 From: Srikar Dronamraju To: Mel Gorman , Peter Zijlstra , Ingo Molnar Cc: Andrea Arcangeli , Johannes Weiner , Linux-MM , LKML , Preeti U Murthy , Linus Torvalds , Srikar Dronamraju Subject: [RFC PATCH 08/10] sched: Prevent a task from migrating immediately after an active balance Date: Tue, 30 Jul 2013 13:18:23 +0530 Message-Id: <1375170505-5967-9-git-send-email-srikar@linux.vnet.ibm.com> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1375170505-5967-1-git-send-email-srikar@linux.vnet.ibm.com> References: <1375170505-5967-1-git-send-email-srikar@linux.vnet.ibm.com> X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13073007-5518-0000-0000-000010B92492 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Once a task has been carefully chosen to be migrated to a destination node from a source node, try to avoid some other cpus moving this task away from the destinagtion node. If not, tasks might end up being in a ping-pong; one cpu pulling it because of numa affinity, the other cpu pulling it for the slight imbalance created because of previous migration (instead of actually trying to pull a task that might lead to more consolidation) Signed-off-by: Srikar Dronamraju --- include/linux/sched.h | 1 + kernel/sched/core.c | 1 + kernel/sched/fair.c | 9 +++++++++ 3 files changed, 11 insertions(+), 0 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index a77c3cd..ba188f1 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1506,6 +1506,7 @@ struct task_struct { unsigned int numa_scan_period; u64 node_stamp; /* migration stamp */ struct callback_head numa_work; + int migrate_seq; #endif /* CONFIG_NUMA_BALANCING */ struct rcu_head rcu; diff --git a/kernel/sched/core.c b/kernel/sched/core.c index e792312..453d989 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1594,6 +1594,7 @@ static void __sched_fork(struct task_struct *p) p->numa_migrate_seq = p->mm ? p->mm->numa_scan_seq - 1 : 0; p->numa_scan_period = sysctl_numa_balancing_scan_delay; p->numa_work.next = &p->numa_work; + p->migrate_seq = 0; #endif /* CONFIG_NUMA_BALANCING */ } diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index e04703e..a99aebc 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1014,6 +1014,7 @@ static void account_numa_dequeue(struct cfs_rq *cfs_rq, struct task_struct *p) struct rq *rq = rq_of(cfs_rq); int curnode = cpu_to_node(cpu_of(rq)); + p->migrate_seq = 0; if (mm && mm->numa_weights) { atomic_dec(&mm->numa_weights[curnode]); atomic_dec(&mm->numa_weights[nr_node_ids]); @@ -4037,6 +4038,13 @@ static bool preferred_node(struct task_struct *p, struct lb_env *env) if (!(env->sd->flags & SD_NUMA)) return false; + if (env->iterations) { + if (!p->migrate_seq) + return true; + + p->migrate_seq--; + return false; + } return (can_numa_migrate_task(p, env->dst_rq, env->src_rq) == 1); } #else @@ -4063,6 +4071,7 @@ static int move_one_task(struct lb_env *env) if (p->on_rq && task_cpu(p) == env->src_rq->cpu) { move_task(p, env); schedstat_inc(env->sd, lb_gained[env->idle]); + p->migrate_seq = 3; return 1; } return 0; -- 1.7.1