Architecture specific implementations for tickless kernel and deferrable timers

[vikram186@gmail.com (Vikram Narayanan)]

On Fri, Apr 22, 2011 at 8:43 AM, Jeff Ohlstein <johlstei@codeaurora.org> wrote:
> Vikram Narayanan wrote:
>> And also, are clocksoure and clockevents dependent on each other? I
>> see in some platforms, that they have used 2 different timers for the
>> above. Can a same clock be used for both clocksource and clockevents?
>> Please throw some light on this. If it can be used so, what ties up
>> the clocksource and clockevent?
>
> You can look at msm for an example of a single timer being used both as
> a clocksource and a clockevent. We end up shutting off the clocksource
> whenever we shut down the clockevent. This does cause some issues.
> Switching clocksources at runtime does not work. It will also cause
> problems if you implement your own sched_clock function, as it will have
> little choice but to return a stale cached value whenever the clockevent
> is disabled, such as in the suspend path.
Thanks for the example. I will refer to that. And I have another
question, If dynamic ticks are implemented, say if I am using the same
clocksource and clockevent, the wall time will only be updated at that
dyn_tick interval. Will that create any issue? or should I use a
constant source for the clocksource? or how to handle this in an
effective way.
* Clocksource and clockevents with the same timer.
* Also I want to make use of the tickless kernel functionality.

Vikram

>
> Jeff
>
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>