Commit-ID: a43455a1d572daf7b730fe12eb747d1e17411365 Gitweb: http://git.kernel.org/tip/a43455a1d572daf7b730fe12eb747d1e17411365 Author: Rik van Riel <[email protected]> AuthorDate: Wed, 4 Jun 2014 16:09:42 -0400 Committer: Ingo Molnar <[email protected]> CommitDate: Wed, 18 Jun 2014 18:29:57 +0200
sched/numa: Ensure task_numa_migrate() checks the preferred node The first thing task_numa_migrate() does is check to see if there is CPU capacity available on the preferred node, in order to move the task there. However, if the preferred node is all busy, we would skip considering that node for tasks swaps in the subsequent loop. This prevents NUMA convergence of tasks on busy systems. However, swapping locations with a task on our preferred nid, when the preferred nid is busy, is perfectly fine. The fix is to also look for a CPU on our preferred nid when it is totally busy. This changes "perf bench numa mem -p 4 -t 20 -m -0 -P 1000" from not converging in 15 minutes on my 4 node system, to converging in 10-20 seconds. Signed-off-by: Rik van Riel <[email protected]> Signed-off-by: Peter Zijlstra <[email protected]> Cc: [email protected] Cc: Linus Torvalds <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- kernel/sched/fair.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index fea7d33..8fbb011 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1302,9 +1302,8 @@ static int task_numa_migrate(struct task_struct *p) groupimp = group_weight(p, env.dst_nid) - groupweight; update_numa_stats(&env.dst_stats, env.dst_nid); - /* If the preferred nid has free capacity, try to use it. */ - if (env.dst_stats.has_free_capacity) - task_numa_find_cpu(&env, taskimp, groupimp); + /* Try to find a spot on the preferred nid. */ + task_numa_find_cpu(&env, taskimp, groupimp); /* No space available on the preferred nid. Look elsewhere. */ if (env.best_cpu == -1) { -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
