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>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index b4a39bb..8af3d24 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1113,6 +1113,8 @@ struct sched_entity {
 	u64			start_runtime;
 	u64			avg_wakeup;
 
+	u64			avg_running;
+
 #ifdef CONFIG_SCHEDSTATS
 	u64			wait_start;
 	u64			wait_max;