Dear, On Tue, Apr 26, 2011 at 10:05 PM, Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx> wrote: > Dear Vikram... > > On Tue, Apr 26, 2011 at 20:55, Vikram Narayanan <vikram186@xxxxxxxxx> wrote: >> Hi, >> >> I want to enable the dynamic tick aka tickless kernel feature for the >> BSP which I am developing. What are all the architecture dependent >> changes that needs to be done for implementing it. > > To the best I know: > > essentially, to achieve tickless ( also know as "no hz"), you need to > reprogram your timer chip, so it just "shoot" whenever needed, not > periodically. And sometimes, you need to round them up, i.e there are > timers which expires in the next 10 ms, 11 ms and 15 ms...so > effectively, better to make them expire at 15 ms if possible. > > so, you need a way to detect the timer expiration (possibly by walking > through active timer list) and decide when the timer chip needs to > shoot interrupt. The rest of the change...of course...still needed > further thinking.... > > NB: AFAIK In x86, HPET is a prerequisite to achieve tickless... maybe > because reprogramming HPET is somewhat way faster than regular PIT I have read about the dynamic tick feature in lwn.net. When I see the source, it seems to have implemented only with the HPET timers. and also, these dynamic ticks are achieved with hrtimers nowadays. http://lxr.linux.no/#linux+v2.6.38/Documentation/timers/highres.txt#L204 Also I believe most of the implementation is moved to the arch independent part with the help of clocksource and clockevents. Do I need to enable hrtimers for enabling the dynamic tick feature.? - Thanks Vikram > > -- > regards, > > Mulyadi Santosa > Freelance Linux trainer and consultant > > blog: the-hydra.blogspot.com > training: mulyaditraining.blogspot.com > _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
