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    SubjectRe: [CFS Bandwidth Control v4 6/7] sched: hierarchical task accounting for SCHED_OTHER
    (2011/02/16 12:18), Paul Turner wrote:
    > @@ -1428,6 +1464,7 @@ enqueue_task_fair(struct rq *rq, struct
    > update_cfs_shares(cfs_rq);
    > }
    >
    > + account_hier_tasks(&p->se, 1);
    > hrtick_update(rq);
    > }
    >
    > @@ -1461,6 +1498,7 @@ static void dequeue_task_fair(struct rq
    > update_cfs_shares(cfs_rq);
    > }
    >
    > + account_hier_tasks(&p->se, -1);
    > hrtick_update(rq);
    > }
    >

    Why hrtick_update() is need to be delayed after modifying nr_running?
    You should not impact current hrtick logic without once mentioning.

    > Index: tip/kernel/sched_rt.c
    > ===================================================================
    > --- tip.orig/kernel/sched_rt.c
    > +++ tip/kernel/sched_rt.c
    > @@ -906,6 +906,8 @@ enqueue_task_rt(struct rq *rq, struct ta
    >
    > if (!task_current(rq, p) && p->rt.nr_cpus_allowed > 1)
    > enqueue_pushable_task(rq, p);
    > +
    > + inc_nr_running(rq);
    > }
    >
    > static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
    > @@ -916,6 +918,8 @@ static void dequeue_task_rt(struct rq *r
    > dequeue_rt_entity(rt_se);
    >
    > dequeue_pushable_task(rq, p);
    > +
    > + dec_nr_running(rq);
    > }
    >
    > /*

    I think similar change for sched_stoptask.c is required.

    In fact I could not boot tip/master with this v4 patchset.
    It reports rcu stall warns without applying following tweak:

    --- a/kernel/sched_stoptask.c
    +++ b/kernel/sched_stoptask.c
    @@ -35,11 +35,13 @@ static struct task_struct *pick_next_task_stop(struct rq *rq
    static void
    enqueue_task_stop(struct rq *rq, struct task_struct *p, int flags)
    {
    + inc_nr_running(rq);
    }

    static void
    dequeue_task_stop(struct rq *rq, struct task_struct *p, int flags)
    {
    + dec_nr_running(rq);
    }


    Thanks,
    H.Seto


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