diff options
| author | Mel Gorman <mgorman@suse.de> | 2013-10-07 11:29:29 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2013-10-09 14:48:02 +0200 |
| commit | 7dbd13ed06513b047216a7ffc718bad9df0660f1 (patch) | |
| tree | 6f752254b51954b129fa3a35f44968342060afdb /kernel/sched | |
| parent | 82727018b0d33d188e9916bcf76f18387484cb04 (diff) | |
sched/numa: Prevent parallel updates to group stats during placement
Having multiple tasks in a group go through task_numa_placement
simultaneously can lead to a task picking a wrong node to run on, because
the group stats may be in the middle of an update. This patch avoids
parallel updates by holding the numa_group lock during placement
decisions.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1381141781-10992-52-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
| -rw-r--r-- | kernel/sched/fair.c | 35 |
1 files changed, 23 insertions, 12 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index c4df2de6ca4a..147349987bfe 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1233,6 +1233,7 @@ static void task_numa_placement(struct task_struct *p) { int seq, nid, max_nid = -1, max_group_nid = -1; unsigned long max_faults = 0, max_group_faults = 0; + spinlock_t *group_lock = NULL; seq = ACCESS_ONCE(p->mm->numa_scan_seq); if (p->numa_scan_seq == seq) @@ -1241,6 +1242,12 @@ static void task_numa_placement(struct task_struct *p) p->numa_migrate_seq++; p->numa_scan_period_max = task_scan_max(p); + /* If the task is part of a group prevent parallel updates to group stats */ + if (p->numa_group) { + group_lock = &p->numa_group->lock; + spin_lock(group_lock); + } + /* Find the node with the highest number of faults */ for_each_online_node(nid) { unsigned long faults = 0, group_faults = 0; @@ -1279,20 +1286,24 @@ static void task_numa_placement(struct task_struct *p) } } - /* - * If the preferred task and group nids are different, - * iterate over the nodes again to find the best place. - */ - if (p->numa_group && max_nid != max_group_nid) { - unsigned long weight, max_weight = 0; - - for_each_online_node(nid) { - weight = task_weight(p, nid) + group_weight(p, nid); - if (weight > max_weight) { - max_weight = weight; - max_nid = nid; + if (p->numa_group) { + /* + * If the preferred task and group nids are different, + * iterate over the nodes again to find the best place. + */ + if (max_nid != max_group_nid) { + unsigned long weight, max_weight = 0; + + for_each_online_node(nid) { + weight = task_weight(p, nid) + group_weight(p, nid); + if (weight > max_weight) { + max_weight = weight; + max_nid = nid; + } } } + + spin_unlock(group_lock); } /* Preferred node as the node with the most faults */ |