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SubjectRe: [PATCH] add requeue task
Nick Piggin writes:
> Con Kolivas wrote:
> > add requeue task
> >
> >
> >
> > ------------------------------------------------------------------------
> >
> > We can requeue tasks for cheaper then doing a complete dequeue followed by
> > an enqueue. Add the requeue_task function and perform it where possible.
> >
> > Change the granularity code to requeue tasks at their best priority
> > instead of changing priority while they're running. This keeps tasks at
> > their top interactive level during their whole timeslice.
> >
>
> I wonder... these things are all in sufficiently rarely used places,
> that the icache miss might be more costly than the operations saved.
>
> But....
>
> > Signed-off-by: Con Kolivas <kernel@kolivas.org>
> >
> > Index: linux-2.6.10-rc1-mm2/kernel/sched.c
> > ===================================================================
> > --- linux-2.6.10-rc1-mm2.orig/kernel/sched.c 2004-11-02 14:48:54.686316718 +1100
> > +++ linux-2.6.10-rc1-mm2/kernel/sched.c 2004-11-02 14:52:51.805763544 +1100
> > @@ -579,6 +579,16 @@ static void enqueue_task(struct task_str
> > }
> >
> > /*
> > + * Put task to the end of the run list without the overhead of dequeue
> > + * followed by enqueue.
> > + */
> > +static void requeue_task(struct task_struct *p, prio_array_t *array)
> > +{
> > + list_del(&p->run_list);
> > + list_add_tail(&p->run_list, array->queue + p->prio);
> > +}

Shouldn't this be

list_move_tail(&p->run_list, array->queue + p->prio);

?

Nikita.
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