From: Peter Zijlstra <peterz@infradead.org>
To: sebastiano spicuglia <spicuglia.sebastiano@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org
Subject: Re: Sched_class documentation
Date: Thu, 17 Jun 2010 19:13:08 +0200 [thread overview]
Message-ID: <1276794788.27822.603.camel@twins> (raw)
In-Reply-To: <AANLkTikuunLAsrtS2GhSkICkYfN_0H0jdZyo7fxjQl9b@mail.gmail.com>
On Thu, 2010-06-17 at 19:02 +0200, sebastiano spicuglia wrote:
> Hi Ingo,
>
> I made many progress. But I have two doubts yet.
> First: what does hrtick_start do?
higher resolution ticks
> I think that: if I call hrtick_start(rq, 500) then, after 500ns, the
> task_tick function will be invocated.
> Is it right?
Yep, instead of waiting for the next system tick is programs a hrtimer
to deliver it -- its disabled by default though, since programming
timers is rather expensive :/
> Second: if my schedule_class decides to preempt the current task, it
> has to call resched_task(rq->curr).
> Is it right?
Either that or resched_cpu(), depending on which is most convenient.
It sets TIF_RESCHED and possibly IPIs the remote CPU. The TIF flag is
then observed (on re-entry to userspace in case of the IPI) and we call
into schedule().
prev parent reply other threads:[~2010-06-17 17:13 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20100523144912.jfmkhsp50kcgk8os@webmail-stud.polimi.it>
[not found] ` <20100525071147.GC5985@elte.hu>
2010-06-17 17:02 ` sebastiano spicuglia
2010-06-17 17:13 ` Peter Zijlstra [this message]
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