lkml.org 
[lkml]   [2012]   [Apr]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
SubjectRe: [PATCH] DLS: cleanup pulling task
From
First add check for CPU online.
Second initialize dmin to be as min as possible.
Third, the preempt check is not available yet=(

Due to re-init of dmin, a couple of preempt checks are removed.

With runqueue lock, a couple of caution checks are also removed.

Finally the jumple lable, skip, is replaced with unlock.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
---
--- a/kernel/sched_dl.c Sat Apr 7 15:00:28 2012
+++ b/kernel/sched_dl.c Sat Apr 7 17:33:44 2012
@@ -1287,71 +1287,53 @@ static void push_dl_tasks(struct rq *rq)

static int pull_dl_task(struct rq *this_rq)
{
- int this_cpu = this_rq->cpu, ret = 0, cpu;
- struct task_struct *p;
- struct rq *src_rq;
- u64 dmin = LONG_MAX;
+ int this_cpu = this_rq->cpu;
+ int cpu;
+ u64 dmin;
+ int ret = 0;

if (likely(!dl_overloaded(this_rq)))
return 0;

- for_each_cpu(cpu, this_rq->rd->dlo_mask) {
+ if (this_rq->dl.dl_nr_running)
+ dmin = this_rq->dl.earliest_dl.curr;
+ else
+ dmin = -1ULL;
+
+ for_each_cpu_and(cpu, this_rq->rd->dlo_mask, cpu_online_mask) {
+ struct task_struct *p;
+ struct rq *src_rq;
+
if (this_cpu == cpu)
continue;

src_rq = cpu_rq(cpu);

- /*
- * It looks racy, abd it is! However, as in sched_rt.c,
- * we are fine with this.
- */
- if (this_rq->dl.dl_nr_running &&
- dl_time_before(this_rq->dl.earliest_dl.curr,
- src_rq->dl.earliest_dl.next))
+ /* Racy without runqueue lock, but we are fine now */
+ if (!dl_time_before(src_rq->dl.earliest_dl.next, dmin))
continue;

- /* Might drop this_rq->lock */
double_lock_balance(this_rq, src_rq);

- /*
- * If there are no more pullable tasks on the
- * rq, we're done with it.
- */
if (src_rq->dl.dl_nr_running <= 1)
- goto skip;
+ goto unlock;

p = pick_next_earliest_dl_task(src_rq, this_cpu);

- /*
- * We found a task to be pulled if:
- * - it preempts our current (if there's one),
- * - it will preempt the last one we pulled (if any).
- */
- if (p && dl_time_before(p->dl.deadline, dmin) &&
- (!this_rq->dl.dl_nr_running ||
- dl_time_before(p->dl.deadline,
- this_rq->dl.earliest_dl.curr))) {
- WARN_ON(p == src_rq->curr);
- WARN_ON(!p->on_rq);
-
- /*
- * Then we pull iff p has actually an earlier
- * deadline than the current task of its runqueue.
- */
- if (dl_time_before(p->dl.deadline,
- src_rq->curr->dl.deadline))
- goto skip;
+ /* With runqueue lock, recheck preempty */
+ if (p && dl_time_before(p->dl.deadline, dmin)) {

- ret = 1;
+ /* We dont pull running task */
+ if (p == src_rq->curr)
+ goto unlock;

deactivate_task(src_rq, p, 0);
set_task_cpu(p, this_cpu);
activate_task(this_rq, p, 0);
+ ret++;
dmin = p->dl.deadline;
-
- /* Is there any other task even earlier? */
}
-skip:
+unlock:
double_unlock_balance(this_rq, src_rq);
}

--

\
 
 \ /
  Last update: 2012-04-07 12:17    [from the cache]
©2003-2011 Jasper Spaans