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    SubjectRe: [PATCH 2/6] sched: rt-bandwidth accounting fix
    Peter Zijlstra wrote:
    > It fixes an accounting bug where we would continue accumulating runtime
    > even though the bandwidth control is disabled. This would lead to very long
    > throttle periods once bandwidth control gets turned on again.
    >
    > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    > ---
    > kernel/sched_rt.c | 11 +++++------
    > 1 file changed, 5 insertions(+), 6 deletions(-)
    >
    > Index: linux-2.6/kernel/sched_rt.c
    > ===================================================================
    > --- linux-2.6.orig/kernel/sched_rt.c
    > +++ linux-2.6/kernel/sched_rt.c
    > @@ -438,9 +438,6 @@ static int sched_rt_runtime_exceeded(str
    > {
    > u64 runtime = sched_rt_runtime(rt_rq);
    >
    > - if (runtime == RUNTIME_INF)
    > - return 0;
    > -
    > if (rt_rq->rt_throttled)
    > return rt_rq_throttled(rt_rq);
    >
    > @@ -491,9 +488,11 @@ static void update_curr_rt(struct rq *rq
    > rt_rq = rt_rq_of_se(rt_se);
    >
    > spin_lock(&rt_rq->rt_runtime_lock);
    > - rt_rq->rt_time += delta_exec;
    > - if (sched_rt_runtime_exceeded(rt_rq))
    > - resched_task(curr);
    > + if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
    > + rt_rq->rt_time += delta_exec;
    > + if (sched_rt_runtime_exceeded(rt_rq))
    > + resched_task(curr);
    > + }
    > spin_unlock(&rt_rq->rt_runtime_lock);
    > }
    > }

    This will make 'disabled' case more expensive, will it not ?
    I mean now we'll have to run balance_runtime() even if throttling is
    disabled.

    Do you guys mind if I make this stuff configurable ? ie Just like
    CONFIG_RT_GROUP_SCHED we could add CONFIG_RT_BANDWIDTH_THROTTLE.

    Max


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