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Date: Wed, 29 Oct 2014 07:22:35 +0800
From: "Li, Aubrey" <aubrey.li@linux.intel.com>
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To: Peter Zijlstra <peterz@infradead.org>
CC: "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        "Brown, Len" <len.brown@intel.com>,
        "alan@linux.intel.com" <alan@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>, "H. Peter Anvin" <hpa@zytor.com>,
        linux-kernel@vger.kernel.org,
        "linux-pm@vger.kernel.org >> Linux PM list" 
	<linux-pm@vger.kernel.org>
Subject: Re: [RFC/PATCH] PM / Sleep: Timer quiesce in freeze state
References: <5446787E.60202@linux.intel.com> <20141024153656.GM12706@worktop.programming.kicks-ass.net> <544DE5CF.9040501@linux.intel.com> <20141027074419.GE10501@worktop.programming.kicks-ass.net> <544F4B31.7050308@linux.intel.com> <20141028082503.GN3337@twins.programming.kicks-ass.net>
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On 2014/10/28 16:25, Peter Zijlstra wrote:
> On Tue, Oct 28, 2014 at 03:52:17PM +0800, Li, Aubrey wrote:
> 
>> Both clocksource and clockevents are not per-cpu device, why do we need
>> to run their suspend callback on *each* cpu?
> 
> Uhm, you mean to say we don't use per-cpu timer lists and per-cpu timer
> hardware for clockevents then?
> 

>>From OS level, currently tick device is per-cpu implementation while
clocksource and clockevent devices are global device.

We already stop tick by clockevents_notify(suspend) on each cpu, that
addresses per-cpu timer list.

And, we already call clocksource_suspend() and clockevents_suspend() in
timekeeping_suspend() on the tick timer CPU. Yes, we didn't suspend
per-cpu timer hardware on x86 because x86 does not have lapic timer
suspend implementation. If we need to implement this, I think we can do
the cross-CPU calls in clocksource/clockevents suspend(), but I didn't
see any necessary we need to do this now.

so, I think we are okay now, :)

Thanks,
-Aubrey