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Subject[PATCH v4 6/7] sched/deadline: Optimize find_later_rq() to select a cache hot cpu
Date
Add the case for iteration of sched_domains without SD_WAKE_AFFINE
flags to select a cpu, this flag may be unset through proc by users.

Signed-off-by: pang.xunlei <pang.xunlei@linaro.org>
---
kernel/sched/deadline.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index e0e8013..01d3aaab 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -1177,6 +1177,7 @@ 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 cachehot_cpu = nr_cpu_ids;

/* Make sure the mask is initialized first */
if (unlikely(!later_mask))
@@ -1219,7 +1220,7 @@ static int find_later_rq(struct task_struct *task)

rcu_read_lock();
for_each_domain(cpu, sd) {
- int best_cpu;
+ int wakeaffine_cpu;
if (sd->flags & SD_WAKE_AFFINE) {

/*
@@ -1232,16 +1233,24 @@ static int find_later_rq(struct task_struct *task)
return this_cpu;
}

- best_cpu = cpumask_first_and(later_mask,
- sched_domain_span(sd));
- if (best_cpu < nr_cpu_ids) {
+ wakeaffine_cpu = cpumask_first_and(later_mask,
+ sched_domain_span(sd));
+ if (wakeaffine_cpu < nr_cpu_ids) {
rcu_read_unlock();
- return best_cpu;
+ return wakeaffine_cpu;
}
+ } else {
+ if (cachehot_cpu >= nr_cpu_ids)
+ cachehot_cpu = cpumask_first_and(later_mask,
+ sched_domain_span(sd));
}
}
rcu_read_unlock();

+ /* Most likely cache-hot */
+ if (cachehot_cpu < nr_cpu_ids)
+ return cachehot_cpu;
+
/*
* At this point, all our guesses failed, we just return
* 'something', and let the caller sort the things out.
--
1.7.9.5


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