linux-kernel - Re: Sched_class documentation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Thu, 17 Jun 2010 19:13:08 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	sebastiano spicuglia <spicuglia.sebastiano@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: Sched_class documentation

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().
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/