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SubjectRe: [PATCH v2] sched: Have do_idle() call __schedule() without enabling preemption
On Wed, 12 Apr 2017 16:48:59 -0700
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com> wrote:
>
> I don't understand why schedule_idle() needs a loop given that
> schedule_preempt_disabled() doesn't have one, but other than

But it does:

void __sched schedule_preempt_disabled(void)
{
sched_preempt_enable_no_resched();
schedule();
preempt_disable();
}

Where we have:

asmlinkage __visible void __sched schedule(void)
{
struct task_struct *tsk = current;

sched_submit_work(tsk);
do {
preempt_disable();
__schedule(false);
sched_preempt_enable_no_resched();
} while (need_resched());
}

Which makes:

void __sched schedule_preempt_disabled(void)
{
struct task_struct *tsk = current;

scehdule_preempt_enable_no_resched();
sched_submit_work(tsk);
do {
preempt_disable();
__schedule(false);
schedule_preempt_enable_no_resched();
} while (need_resched());
preempt_disable();
}

My schedule_idle() is simply schedule_preempt_disabled() without the
change in preemption and no call to sched_submit_work().


> that, for whatever it is worth, it looks good to me.
>

Does this mean I can change the Cc: to Acked-by: ?

-- Steve


> > +void __sched schedule_idle(void)
> > +{
> > + do {
> > + __schedule(false);
> > + } while (need_resched());
> > +}
> > +

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