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.p...@lge.com> --- kernel/sched/deadline.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 0223694..ada264c 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1325,6 +1325,7 @@ static int find_later_rq(struct task_struct *task) struct cpumask *later_mask = this_cpu_cpumask_var_ptr(local_cpu_mask_dl); int this_cpu = smp_processor_id(); int cpu = task_cpu(task); + int fallback_cpu = -1; /* Make sure the mask is initialized first */ if (unlikely(!later_mask)) @@ -1385,6 +1386,15 @@ static int find_later_rq(struct task_struct *task) * already under consideration through later_mask. */ 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; } @@ -1393,6 +1403,13 @@ static int find_later_rq(struct task_struct *task) rcu_read_unlock(); /* + * If fallback_cpu is valid, all our guesses failed *except* for + * SD_PREFER_SIBLING domain. Now, we can return the fallback cpu. + */ + if (fallback_cpu != -1) + return fallback_cpu; + + /* * At this point, all our guesses failed, we just return * 'something', and let the caller sort the things out. */ -- 1.9.1