On Wed, Oct 15, 2014 at 10:25 AM, Ran Shalit <ranshalit@xxxxxxxxx> wrote: > Hello, > > Is there anyone who can please explain the relation between SW sleep > (such as udelay), to change of C-state as done by cpuidle ? These are two different things, Ran. udelay is a way to put simple delay between two functions. The cpu will continue to perform other operations in a multithreded platform. CPUIdle sleep states are mainly to achieve power saving by programming cpus to difference states depending on how much time (estimated) a cpu is going to be idle with algorithm. So each state will have latency associated with it - enter, exit latency. If the cpu idle time falls within any of C-state's latency that will be programmed. In different state cpu will be programmed with different modes to achieve diff power saving. > How is wakeup done ? As far as I understand udelay is sw delay not HW. System Wake up can be achieved by programming a wakeup source such as keypad. > > Thanks for you comments, > Ran > -- > To unsubscribe from this list: send the line "unsubscribe linux-pm" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Thanks and Regards Pramod -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
