commit ad4b78bbcbab66998b05d422ac6106b645796e54
author Peter Zijlstra <peterz@infradead.org> Wed Sep 16 12:31:31 2009 +0200
committer Ingo Molnar <mingo@elte.hu> Thu Sep 17 10:17:25 2009 +0200
tree 45f3561f4bd6b886948a3b0eea64edab9bab9eda
parent eb24073bc1fe3e569a855cf38d529fb650c35524

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>

kernel/sched_debug.c

diff --git a/kernel/sched_debug.c b/kernel/sched_debug.c
index 5ddbd08..efb8440 100644
--- a/kernel/sched_debug.c
+++ b/kernel/sched_debug.c
@@ -395,6 +395,7 @@
 	PN(se.sum_exec_runtime);
 	PN(se.avg_overlap);
 	PN(se.avg_wakeup);
+	PN(se.avg_running);
 
 	nr_switches = p->nvcsw + p->nivcsw;