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.
The fourth patch is another user of the notifiers, a trivial one.
Thanks,
p.s. For the reference, the old discussion about CPU/PM idle notifiers: http://lkml.org/lkml/2011/6/27/391