sched: Add new wakeup preemption mode: WAKEUP_RUNNING
commitad4b78bbcbab66998b05d422ac6106b645796e54
authorPeter Zijlstra <peterz@infradead.org>
Wed, 16 Sep 2009 10:31:31 +0000 (16 12:31 +0200)
committerIngo Molnar <mingo@elte.hu>
Thu, 17 Sep 2009 08:17:25 +0000 (17 10:17 +0200)
tree45f3561f4bd6b886948a3b0eea64edab9bab9eda
parenteb24073bc1fe3e569a855cf38d529fb650c35524
sched: Add new wakeup preemption mode: WAKEUP_RUNNING

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>
include/linux/sched.h
kernel/sched.c
kernel/sched_debug.c
kernel/sched_fair.c
kernel/sched_features.h