Messages in this thread Patch in this message | | | From | Byungchul Park <> | Subject | [PATCH v3 3/3] sched/rt: Add support for SD_PREFER_SIBLING on find_lowest_rq() | Date | Thu, 23 Mar 2017 11:12:49 +0900 |
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It would be better to avoid pushing tasks to other cpu within a SD_PREFER_SIBLING domain, instead, get more chances to check other siblings.
Signed-off-by: Byungchul Park <byungchul.park@lge.com> --- kernel/sched/rt.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 979b734..6332b2ad 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1624,6 +1624,7 @@ static int find_lowest_rq(struct task_struct *task) struct cpumask *lowest_mask = this_cpu_cpumask_var_ptr(local_cpu_mask); int this_cpu = smp_processor_id(); int cpu = task_cpu(task); + int fallback_cpu = -1; /* Make sure the mask is initialized first */ if (unlikely(!lowest_mask)) @@ -1671,6 +1672,15 @@ static int find_lowest_rq(struct task_struct *task) best_cpu = cpumask_first_and(lowest_mask, sched_domain_span(sd)); if (best_cpu < nr_cpu_ids) { + /* + * If current domain is SD_PREFER_SIBLING + * flaged, we have to get more chances to + * check other siblings. + */ + if (sd->flags & SD_PREFER_SIBLING) { + fallback_cpu = best_cpu; + continue; + } rcu_read_unlock(); return best_cpu; } @@ -1679,6 +1689,13 @@ static int find_lowest_rq(struct task_struct *task) rcu_read_unlock(); /* + * If fallback_cpu is valid, all our quesses failed *except* for + * SD_PREFER_SIBLING domain. Now, we can return the fallback cpu. + */ + if (fallback_cpu != -1) + return fallback_cpu; + + /* * And finally, if there were no matches within the domains * just give the caller *something* to work with from the compatible * locations. -- 1.9.1
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