* santosh shilimkar <santosh.shilim...@oracle.com> [150121 13:31]: > On 1/21/2015 12:43 PM, Tony Lindgren wrote: > >* santosh shilimkar <santosh.shilim...@oracle.com> [150121 12:16]: > >> > >>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 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
