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    SubjectRe: [PATCH 1/7] sched/core: uclamp: add CPU clamp groups accounting
    On 13-Apr 12:22, Peter Zijlstra wrote:
    > On Fri, Apr 13, 2018 at 10:26:48AM +0200, Peter Zijlstra wrote:
    > > On Mon, Apr 09, 2018 at 05:56:09PM +0100, Patrick Bellasi wrote:
    > > > +static inline void uclamp_cpu_get(struct task_struct *p, int cpu, int clamp_id)
    > > > +{
    > > > + struct uclamp_cpu *uc_cpu = &cpu_rq(cpu)->uclamp[clamp_id];
    > >
    > > > +static inline void uclamp_cpu_put(struct task_struct *p, int cpu, int clamp_id)
    > > > +{
    > > > + struct uclamp_cpu *uc_cpu = &cpu_rq(cpu)->uclamp[clamp_id];
    > >
    > > That all seems daft, since you already have rq at the call site.
    > >
    > > > +static inline void uclamp_task_update(struct rq *rq, struct task_struct *p)
    > > > +{
    > > > + int cpu = cpu_of(rq);
    > > > + int clamp_id;
    > > > +
    > > > + /* The idle task does not affect CPU's clamps */
    > > > + if (unlikely(p->sched_class == &idle_sched_class))
    > > > + return;
    > > > + /* DEADLINE tasks do not affect CPU's clamps */
    > > > + if (unlikely(p->sched_class == &dl_sched_class))
    > > > + return;
    > >
    > > This is wrong; it misses the stop_sched_class.
    > >
    > > And since you're looking at sched_class anyway, maybe put a marker in
    > > there:
    > >
    > > if (!p->sched_class->has_clamping)
    > > return;
    >
    > Alternatively, we could simply add uclamp_task_{en,de}queue() into
    > {en,de}queue_task_{fair,rt}().

    I like better your first proposal, I think it makes sense to factor
    out in core code used by both RT and FAIR the same way.

    Do you have a strong preference?

    > > > + for (clamp_id = 0; clamp_id < UCLAMP_CNT; ++clamp_id) {
    > > > + if (uclamp_task_affects(p, clamp_id))
    > > > + uclamp_cpu_put(p, cpu, clamp_id);
    > > > + else
    > > > + uclamp_cpu_get(p, cpu, clamp_id);
    > > > + }
    > > > +}

    --
    #include <best/regards.h>

    Patrick Bellasi

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