From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752050AbaAQG1y (ORCPT ); Fri, 17 Jan 2014 01:27:54 -0500 Received: from shelob.surriel.com ([74.92.59.67]:44861 "EHLO shelob.surriel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751537AbaAQG1w (ORCPT ); Fri, 17 Jan 2014 01:27:52 -0500 From: riel@redhat.com To: linux-kernel@vger.kernel.org Cc: linux-mm@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, chegu_vinod@hp.com, mgorman@suse.de, Rik van Riel , Rik van Riel Subject: [PATCH 3/6] numa,sched: build per numa_group active node mask from faults_from statistics Date: Fri, 17 Jan 2014 01:17:33 -0500 Message-Id: <1389939456-9541-4-git-send-email-riel@redhat.com> X-Mailer: git-send-email 1.8.4.2 In-Reply-To: <1389939456-9541-1-git-send-email-riel@redhat.com> References: <1389939456-9541-1-git-send-email-riel@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Rik van Riel The faults_from statistics are used to maintain an active_nodes nodemask per numa_group. This allows us to be smarter about when to do numa migrations. Cc: Peter Zijlstra Cc: Mel Gorman Cc: Ingo Molnar Cc: Chegu Vinod Signed-off-by: Rik van Riel Signed-off-by: Rik van Riel --- kernel/sched/fair.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 1945ddc..aa680e2 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -885,6 +885,7 @@ struct numa_group { struct list_head task_list; struct rcu_head rcu; + nodemask_t active_nodes; unsigned long total_faults; unsigned long *faults_from; unsigned long faults[0]; @@ -1275,6 +1276,38 @@ static void numa_migrate_preferred(struct task_struct *p) } /* + * Iterate over the nodes from which NUMA hinting faults were triggered, in + * other words where the CPUs that incurred NUMA hinting faults are. The + * bitmask is used to limit NUMA page migrations, and spread out memory + * between the actively used nodes. To prevent flip-flopping, and excessive + * page migrations, nodes are added when they cause over 40% of the maximum + * number of faults, but only removed when they drop below 20%. + */ +static void update_numa_active_node_mask(struct task_struct *p) +{ + unsigned long faults, max_faults = 0; + struct numa_group *numa_group = p->numa_group; + int nid; + + for_each_online_node(nid) { + faults = numa_group->faults_from[task_faults_idx(nid, 0)] + + numa_group->faults_from[task_faults_idx(nid, 1)]; + if (faults > max_faults) + max_faults = faults; + } + + for_each_online_node(nid) { + faults = numa_group->faults_from[task_faults_idx(nid, 0)] + + numa_group->faults_from[task_faults_idx(nid, 1)]; + if (!node_isset(nid, numa_group->active_nodes)) { + if (faults > max_faults * 4 / 10) + node_set(nid, numa_group->active_nodes); + } else if (faults < max_faults * 2 / 10) + node_clear(nid, numa_group->active_nodes); + } +} + +/* * When adapting the scan rate, the period is divided into NUMA_PERIOD_SLOTS * increments. The more local the fault statistics are, the higher the scan * period will be for the next scan window. If local/remote ratio is below @@ -1416,6 +1449,7 @@ static void task_numa_placement(struct task_struct *p) update_task_scan_period(p, fault_types[0], fault_types[1]); if (p->numa_group) { + update_numa_active_node_mask(p); /* * If the preferred task and group nids are different, * iterate over the nodes again to find the best place. @@ -1478,6 +1512,8 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags, /* Second half of the array tracks where faults come from */ grp->faults_from = grp->faults + 2 * nr_node_ids; + node_set(task_node(current), grp->active_nodes); + for (i = 0; i < 4*nr_node_ids; i++) grp->faults[i] = p->numa_faults[i]; @@ -1547,6 +1583,8 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags, my_grp->nr_tasks--; grp->nr_tasks++; + update_numa_active_node_mask(p); + spin_unlock(&my_grp->lock); spin_unlock(&grp->lock); -- 1.8.4.2