* santosh shilimkar [off-list ref] [150121 13:31]:

On 1/21/2015 12:43 PM, Tony Lindgren wrote:

quoted

* santosh shilimkar [off-list ref] [150121 12:16]:

quoted

TWD is useless on this machine since single core and TWD
as know die in low power states. All the broadcast stuff
is for SMP machines.

Hmm it seems we should still use TWD during runtime and
swich over to the gptimer for idle states for wake-up
events.

Well timer wheel code don't support it so if you are serious,
some one needs to do that. For me, it is not worth at all.
You will have more to loose than gain with these time switching
schemes since you have to keep 2 times alive, do switching, loose
the idle time.

All of that is to save few CPU cycles since TWD is closer
compared to other SOC timer.

Anyways I will let you fight it out but IIRC, I had a
discussion a while back with tglx in one of the conference
and the conclusion was it not worth doing.
Rather TWD hardware on SOC should be made wakeup capable
and then everything is good.

Till you have support, using TWD on AM43XX will break CPUIDLE.
Not sure if it is supported or some one cares about it. Just
keep that aspect in mind.

Yes sure I'm aware of this. It should be easy to profile the
speed gain to see if it would make much of a difference
before starting to tinker with that.

The way I think it's possible to do would be to copy the TWD
timer value to a wake-up capable gptimer before hitting any
deeper idle state. Of course some aux timer support might be
still needed :)

Regards,

Tony