diff options
| author | Rik van Riel <riel@redhat.com> | 2014-08-04 13:23:28 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2014-08-12 12:48:23 +0200 |
| commit | 83d7f2424741c9dc76c21377c9d00d47abaf88df (patch) | |
| tree | eddb9a5732788c00247c3bb430b14bea4bc6c953 /kernel/sched/fair.c | |
| parent | b932c03c34f3b03c7364c06aa8cae5b74609fc41 (diff) | |
sched/numa: Fix numa capacity computation
Commit c61037e9 fixes the phenomenon of 'fantom' cores due to
N*frac(smt_power) >= 1 by limiting the capacity to the actual
number of cores in the load balancing code.
This patch applies the same correction to the NUMA balancing
code.
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: mgorman@suse.de
Cc: vincent.guittot@linaro.org
Cc: Morten.Rasmussen@arm.com
Cc: nicolas.pitre@linaro.org
Cc: efault@gmx.de
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1407173008-9334-3-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/fair.c')
| -rw-r--r-- | kernel/sched/fair.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index e1cf419c3c7..1413c44ce8a 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1038,7 +1038,8 @@ struct numa_stats { */ static void update_numa_stats(struct numa_stats *ns, int nid) { - int cpu, cpus = 0; + int smt, cpu, cpus = 0; + unsigned long capacity; memset(ns, 0, sizeof(*ns)); for_each_cpu(cpu, cpumask_of_node(nid)) { @@ -1062,8 +1063,12 @@ static void update_numa_stats(struct numa_stats *ns, int nid) if (!cpus) return; - ns->task_capacity = - DIV_ROUND_CLOSEST(ns->compute_capacity, SCHED_CAPACITY_SCALE); + /* smt := ceil(cpus / capacity), assumes: 1 < smt_power < 2 */ + smt = DIV_ROUND_UP(SCHED_CAPACITY_SCALE * cpus, ns->compute_capacity); + capacity = cpus / smt; /* cores */ + + ns->task_capacity = min_t(unsigned, capacity, + DIV_ROUND_CLOSEST(ns->compute_capacity, SCHED_CAPACITY_SCALE)); ns->has_free_capacity = (ns->nr_running < ns->task_capacity); } |