From: afzal.mohd.ma@gmail.com (Afzal Mohammed)
To: linux-arm-kernel@lists.infradead.org
Subject: Dropping "depends on SMP" for HAVE_ARM_TWD -- take 2
Date: Mon, 5 Oct 2015 17:19:40 +0530 [thread overview]
Message-ID: <20151005114940.GA4448@afzalpc> (raw)
In-Reply-To: <20151005054652.GI26391@xsjsorenbubuntu>
Hi,
On Sun, Oct 04, 2015 at 10:46:52PM -0700, S?ren Brinkmann wrote:
> On Sat, 2015-10-03 at 11:12AM +0100, Marc Zyngier wrote:
> > Indeed, I cannot see any code that does that in the GT driver. But if
> > you have an A9 MP, you probably want to stick to TWD, which gives you a
> > per-cpu timer instead of a global timer that will require IPIs to other
> > CPUs.
>
> I think the TWD only provides a clock_event device. Clocksource and
> schedclock would have to be provided by something else.
If no clocksource, sched clock is provided, default jiffies based ones
would be sufficient for single core, no ?, though not a preferred one.
Regards
afzal
> I looked at that once. IIRC, the problems are schedclock and clocksource.
> Other than a clockevent device which can be adjusted for frequency
> changes, there is (at least was) no such mechanism for clocksources and
> schedclock. Those are required to run at a stable frequency at all times
next prev parent reply other threads:[~2015-10-05 11:49 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-02 9:52 Dropping "depends on SMP" for HAVE_ARM_TWD -- take 2 Mason
2015-10-02 13:24 ` Mason
2015-10-02 18:02 ` Stephen Boyd
2015-10-02 18:48 ` Felipe Balbi
2015-10-02 18:55 ` Russell King - ARM Linux
2015-10-02 19:18 ` Felipe Balbi
2015-10-02 18:50 ` Mason
2015-10-02 19:41 ` Stephen Boyd
2015-10-02 23:34 ` Måns Rullgård
2015-10-03 9:32 ` Marc Zyngier
2015-10-03 9:49 ` Mason
2015-10-03 10:12 ` Marc Zyngier
2015-10-05 5:46 ` Sören Brinkmann
2015-10-05 7:38 ` Mason
2015-10-05 9:03 ` Linus Walleij
2015-10-05 11:49 ` Afzal Mohammed [this message]
2015-10-05 15:13 ` Sören Brinkmann
2015-10-05 15:25 ` Russell King - ARM Linux
2015-10-06 8:21 ` Mason
2015-10-06 19:38 ` Stephen Boyd
2015-10-06 20:01 ` Felipe Balbi
2015-10-06 20:17 ` Mason
2015-10-06 21:05 ` Felipe Balbi
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