Commit-ID: 83d7f2424741c9dc76c21377c9d00d47abaf88df Gitweb: http://git.kernel.org/tip/83d7f2424741c9dc76c21377c9d00d47abaf88df Author: Rik van Riel <r...@redhat.com> AuthorDate: Mon, 4 Aug 2014 13:23:28 -0400 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Tue, 12 Aug 2014 12:48:23 +0200
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 <r...@redhat.com> Signed-off-by: Peter Zijlstra <pet...@infradead.org> Cc: mgor...@suse.de Cc: vincent.guit...@linaro.org Cc: morten.rasmus...@arm.com Cc: nicolas.pi...@linaro.org Cc: efa...@gmx.de Cc: Linus Torvalds <torva...@linux-foundation.org> Link: http://lkml.kernel.org/r/1407173008-9334-3-git-send-email-r...@redhat.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- kernel/sched/fair.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index e1cf419..1413c44 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); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
