On Wed, 2012-02-08 at 05:39 +0400, Anton Vorontsov wrote: > Hi all, > > For some drivers we need to know when scheduler is idling. The most > straightforward way is to gracefully hook into the idle loop. > > On x86 there are "CPU idle" notifiers in the inner idle loop, but > scheduler idle notifiers are different. These notifiers do not run on > every invocation/exit from cpuidle, instead they used to notify about > scheduler state changes, not HW states. > > In other words, CPU idle notifiers work inside while(!need_resched()) > loop (nested into idle loop), while scheduler idle notifier work > outside of the loop. > > The first two patches consolidate scheduler idle entry/exit > points, and converts architectures to this new API. > > The third patch is a new cpufreq governor, the commit message > briefly describes it. Argh, no.. cpufreq so sucks rocks. Can we please just scrap it and write an entirely new infrastructure that is much more connected to the scheduler and do away with this stupid need to set P-states from a schedulable context. We can maybe keep cpufreq around for the broken ass hardware that needs to schedule in order to change its state, but gah. We're going to do per-task avg-load tracking soon (https://lkml.org/lkml/2012/2/1/763) if you can use that (if not, tell why) you can do task based policy and migrate the P-state/freq along with tasks. By keeping per-task avg-runtime and accounting on migration we can compute an avg-runtime per cpu, and select a freq based on that to either minimize idle time (if that's what your platform wants) or boost and run to idle right along with scheduling on wakeup and sleep. Arjan talked about something like that several times.. and I always forgets what policy is best for what chips etc. All I know is that cpufreq sucks because its strictly per-cpu and oblivious to task movement. -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
