sched: let +nice tasks have smaller impact

Michel Dänzr has bisected an interactivity problem with
plus-reniced tasks back to this commit:

 810e95ccd5 is first bad commit
 commit 810e95ccd5
 Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
 Date:   Mon Oct 15 17:00:14 2007 +0200

 sched: another wakeup_granularity fix

      unit mis-match: wakeup_gran was used against a vruntime

fix this by assymetrically scaling the vtime of positive reniced
tasks.

Bisected-by: Michel Dänzer <michel@tungstengraphics.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Peter Zijlstra 2008-01-31 22:45:22 +01:00 committed by Ingo Molnar
parent 296825cbe1
commit ef9884e6f2

View file

@ -1106,7 +1106,11 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p)
}
gran = sysctl_sched_wakeup_granularity;
if (unlikely(se->load.weight != NICE_0_LOAD))
/*
* More easily preempt - nice tasks, while not making
* it harder for + nice tasks.
*/
if (unlikely(se->load.weight > NICE_0_LOAD))
gran = calc_delta_fair(gran, &se->load);
if (pse->vruntime + gran < se->vruntime)