* [PATCH] sched: fix rt-bandwidth hotplug race
@ 2008-08-14 13:49 Peter Zijlstra
2008-08-14 13:51 ` Ingo Molnar
0 siblings, 1 reply; 2+ messages in thread
From: Peter Zijlstra @ 2008-08-14 13:49 UTC (permalink / raw)
To: Ingo Molnar, Alex Nixon; +Cc: linux-kernel
Subject: sched: fix rt-bandwidth hotplug race
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Thu Aug 14 15:42:44 CEST 2008
When we hot-unplug a cpu and rebuild the sched-domain, all cpus will be
detatched. Alex observed the case where a runqueue was stealing bandwidth
from an already disabled runqueue to satisfy its own needs.
Stop this by skipping over already disabled runqueues.
Reported-by: Alex Nixon <alex.nixon@citrix.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Alex Nixon <alex.nixon@citrix.com>
---
kernel/sched_rt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
Index: linux-2.6/kernel/sched_rt.c
===================================================================
--- linux-2.6.orig/kernel/sched_rt.c
+++ linux-2.6/kernel/sched_rt.c
@@ -298,7 +298,7 @@ static void __disable_runtime(struct rq
struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
s64 diff;
- if (iter == rt_rq)
+ if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
continue;
spin_lock(&iter->rt_runtime_lock);
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] sched: fix rt-bandwidth hotplug race
2008-08-14 13:49 [PATCH] sched: fix rt-bandwidth hotplug race Peter Zijlstra
@ 2008-08-14 13:51 ` Ingo Molnar
0 siblings, 0 replies; 2+ messages in thread
From: Ingo Molnar @ 2008-08-14 13:51 UTC (permalink / raw)
To: Peter Zijlstra; +Cc: Alex Nixon, linux-kernel
* Peter Zijlstra <peterz@infradead.org> wrote:
> Subject: sched: fix rt-bandwidth hotplug race
> From: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Date: Thu Aug 14 15:42:44 CEST 2008
>
> When we hot-unplug a cpu and rebuild the sched-domain, all cpus will be
> detatched. Alex observed the case where a runqueue was stealing bandwidth
> from an already disabled runqueue to satisfy its own needs.
>
> Stop this by skipping over already disabled runqueues.
>
> Reported-by: Alex Nixon <alex.nixon@citrix.com>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> Tested-by: Alex Nixon <alex.nixon@citrix.com>
applied to tip/sched/urgent - thanks!
Ingo
^ permalink raw reply [flat|nested] 2+ messages in thread
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2008-08-14 13:49 [PATCH] sched: fix rt-bandwidth hotplug race Peter Zijlstra
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