From ef9884e6f29bbe1075204f962a00f7533bf7e8f3 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Thu, 31 Jan 2008 22:45:22 +0100
Subject: [PATCH] sched: let +nice tasks have smaller impact
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Michel Dänzr has bisected an interactivity problem with
plus-reniced tasks back to this commit:
810e95ccd58d91369191aa4ecc9e6d4a10d8d0c8 is first bad commit
commit 810e95ccd58d91369191aa4ecc9e6d4a10d8d0c8
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>
---
kernel/sched_fair.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index cf958aefac33c..6c091d6e159d0 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -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)
--
2.30.2