Messages in this thread Patch in this message | | | Subject | Re: RFC [patch] sched,cgroup_sched: convince RT_GROUP_SCHED throttle to work | From | Peter Zijlstra <> | Date | Sat, 14 Apr 2012 13:10:47 +0200 |
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On Tue, 2012-04-10 at 11:08 +0200, Mike Galbraith wrote:
> sched,rt: fix isolated CPUs leaving root_task_group indefinitely throttled > > Root task group bandwidth replenishment must service all CPUs regardless of > where it was last started. > > Signed-off-by: Mike Galbraith <efault@gmx.de> > --- > kernel/sched/rt.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > --- a/kernel/sched/rt.c > +++ b/kernel/sched/rt.c > @@ -782,6 +782,19 @@ static int do_sched_rt_period_timer(stru > const struct cpumask *span; > > span = sched_rt_period_mask(); > +#ifdef CONFIG_RT_GROUP_SCHED > + /* > + * FIXME: isolated CPUs should really leave the root task group,
No no, that's the wrong fix, the right fix is to remove isolcpus :-)
> + * 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);
I guess the alternative 'fix' is to not account the rt_runtime on isolated cpus.. does something like the below actually work?
--- kernel/sched/rt.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 44af55e..dc2b5b6 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -922,6 +922,9 @@ static void update_curr_rt(struct rq *rq) if (!rt_bandwidth_enabled()) return; + if (cpumask_test_cpu(cpu_of(rq), cpu_isolated_map)) + return; + for_each_sched_rt_entity(rt_se) { rt_rq = rt_rq_of_se(rt_se);
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