sched: introduce se->vruntime

introduce se->vruntime as a sum of weighted delta-exec's, and use that
as the key into the tree.

the idea to use absolute virtual time as the basic metric of scheduling
has been first raised by William Lee Irwin, advanced by Tong Li and first
prototyped by Roman Zippel in the "Really Fair Scheduler" (RFS) patchset.

also see:

   http://lkml.org/lkml/2007/9/2/76

for a simpler variant of this patch.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 3c38a5040e8f..5e5c457fba86 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -902,6 +902,7 @@ struct sched_entity {
 
         u64                     exec_start;
         u64                     sum_exec_runtime;
+        u64                     vruntime;
         u64                     prev_sum_exec_runtime;
         u64                     wait_start_fair;
         u64                     sleep_start_fair;