| Date | Wed, 9 Oct 2013 10:30:43 -0700 | From | tip-bot for Rik van Riel <> | Subject | [tip:sched/core] sched/numa: Fix placement of workloads spread across multiple nodes |
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Commit-ID: e1dda8a797b59d7ec4b17e393152ec3273a552d5 Gitweb: http://git.kernel.org/tip/e1dda8a797b59d7ec4b17e393152ec3273a552d5 Author: Rik van Riel <riel@redhat.com> AuthorDate: Mon, 7 Oct 2013 11:29:19 +0100 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Wed, 9 Oct 2013 14:47:43 +0200
sched/numa: Fix placement of workloads spread across multiple nodes
The load balancer will spread workloads across multiple NUMA nodes, in order to balance the load on the system. This means that sometimes a task's preferred node has available capacity, but moving the task there will not succeed, because that would create too large an imbalance.
In that case, other NUMA nodes need to be considered.
Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Mel Gorman <mgorman@suse.de> 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/1381141781-10992-42-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org> --- kernel/sched/fair.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 09aac90..aa561c8 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1104,13 +1104,12 @@ static int task_numa_migrate(struct task_struct *p) imp = task_faults(env.p, env.dst_nid) - faults; update_numa_stats(&env.dst_stats, env.dst_nid); - /* - * If the preferred nid has capacity then use it. Otherwise find an - * alternative node with relatively better statistics. - */ - if (env.dst_stats.has_capacity) { + /* If the preferred nid has capacity, try to use it. */ + if (env.dst_stats.has_capacity) task_numa_find_cpu(&env, imp); - } else { + + /* No space available on the preferred nid. Look elsewhere. */ + if (env.best_cpu == -1) { for_each_online_node(nid) { if (nid == env.src_nid || nid == p->numa_preferred_nid) continue;
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