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From: "Mitchell Erblich" <erblichs@earthlink.net>
To: "Ingo Molnar" <mingo@elte.hu>
Cc: "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: Question: RT schedular : task_tick_rt(struct rq *rq, struct task_struct *p) : decreases overhead when  rq->nr_running == 1
Date: Tue, 7 Aug 2007 15:54:41 -0700	[thread overview]
Message-ID: <000501c7d945$f30af1a0$6501a8c0@earthlink.net> (raw)

Ingo Molnar and group,

If their is a single RT task on this rq, then why not just reset the
timeslice and return??? Just MAYBE decreasing re-scheduling
overhead..

Thus,,,,

After
    p->time_slice = static_prio_timeslice(p->static_prio);

Why isn't their a check like
    if  (rq->nr_running == 1)
         return;

Which world remove the need for any recheduling
or requeue'ing...

Mitchell Erblich
FYI: below is believed to be a snap of the current/ orig func
-----------------------------


+static void task_tick_rt(struct rq *rq, struct task_struct *p)
+{
+ /*
+  * RR tasks need a special form of timeslice management.
+  * FIFO tasks have no timeslices.
+  */
+ if (p->policy != SCHED_RR)
+  return;
+
+ if (--p->time_slice)
+  return;
+
+ p->time_slice = static_prio_timeslice(p->static_prio);
+ set_tsk_need_resched(p);
+
+ /* put it at the end of the queue: */
+ requeue_task_rt(rq, p);
+}

             reply	other threads:[~2007-08-07 22:56 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-08-07 22:54 Mitchell Erblich [this message]
2007-08-08 12:34 ` Ingo Molnar
2007-08-09  8:11   ` Dmitry Adamushko
2007-08-09  8:26     ` Ingo Molnar
2007-08-09  8:36       ` Ingo Molnar
2007-08-09  8:39         ` Dmitry Adamushko

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