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sched,rt: fix isolated CPUs leaving root_task_group indefinitely throttled

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Root task group bandwidth replenishment must service all CPUs, regardless of
where the timer was last started, and regardless of the isolation mechanism,
lest 'Quoth the Raven, "Nevermore"' become rt scheduling policy.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1344326558.6968.25.camel@marge.simpson.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Mike Galbraith 2012-08-07 10:02:38 +02:00 committed by Thomas Gleixner
parent 35cf4e50b1
commit e221d028bb
1 changed files with 13 additions and 0 deletions
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13
kernel/sched/rt.c
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@ -788,6 +788,19 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
const struct cpumask *span;
span = sched_rt_period_mask();
#ifdef CONFIG_RT_GROUP_SCHED
/*
* FIXME: isolated CPUs should really leave the root task group,
* whether they are isolcpus or were isolated via cpusets, lest
* the timer run on a CPU which does not service all runqueues,
* potentially leaving other CPUs indefinitely throttled. If
* isolation is really required, the user will turn the throttle
* off to kill the perturbations it causes anyway. Meanwhile,
* this maintains functionality for boot and/or troubleshooting.
*/
if (rt_b == &root_task_group.rt_bandwidth)
span = cpu_online_mask;
#endif
for_each_cpu(i, span) {
int enqueue = 0;
struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);