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sched: Add new wakeup preemption mode: WAKEUP_RUNNING

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Create a new wakeup preemption mode, preempt towards tasks that run
shorter on avg. It sets next buddy to be sure we actually run the task
we preempted for.

Test results:

 root@twins:~# while :; do :; done &
 [1] 6537
 root@twins:~# while :; do :; done &
 [2] 6538
 root@twins:~# while :; do :; done &
 [3] 6539
 root@twins:~# while :; do :; done &
 [4] 6540

 root@twins:/home/peter# ./latt -c4 sleep 4
 Entries: 48 (clients=4)

 Averages:
 ------------------------------
        Max          4750 usec
        Avg           497 usec
        Stdev         737 usec

 root@twins:/home/peter# echo WAKEUP_RUNNING > /debug/sched_features

 root@twins:/home/peter# ./latt -c4 sleep 4
 Entries: 48 (clients=4)

 Averages:
 ------------------------------
        Max            14 usec
        Avg             5 usec
        Stdev           3 usec

Disabled by default - needs more testing.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <new-submission>
This commit is contained in:
Peter Zijlstra
2009-09-16 12:31:31 +02:00
committed by Ingo Molnar
parent eb24073bc1
commit ad4b78bbcb
5 changed files with 29 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
kernel/sched_fair.c
View File

@@ -1605,9 +1605,6 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
return;
}
if (!sched_feat(WAKEUP_PREEMPT))
return;
if ((sched_feat(WAKEUP_SYNC) && sync) ||
(sched_feat(WAKEUP_OVERLAP) &&
(se->avg_overlap < sysctl_sched_migration_cost &&
@@ -1616,6 +1613,17 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
return;
}
if (sched_feat(WAKEUP_RUNNING)) {
if (pse->avg_running < se->avg_running) {
set_next_buddy(pse);
resched_task(curr);
return;
}
}
if (!sched_feat(WAKEUP_PREEMPT))
return;
find_matching_se(&se, &pse);
BUG_ON(!pse);