On Mon, Nov 11, 2013 at 11:33:45AM +0000, Catalin Marinas wrote: > My understanding from the recent discussions is that the scheduler > should decide directly on the C-state (or rather the deepest C-state > possible since we don't want to duplicate the backend logic for > synchronising CPUs going up or down). This means that the scheduler > needs to know about C-state target residency, wake-up latency (I think > we can leave coupled C-states to the backend, there is some complex > synchronisation which I wouldn't duplicate). > > Alternatively (my preferred approach), we get the scheduler to predict > and pass the expected residency and latency requirements down to a > power driver and read back the actual C-states for making task > placement decisions. Some of the menu governor prediction logic could > be turned into a library and used by the scheduler. Basically what > this tries to achieve is better scheduler awareness of the current > C-states decided by a cpuidle/power driver based on the scheduler > constraints.
Ah yes.. so I _think_ the scheduler wants to eventually know about idle topology constraints. But we can get there in a gradual fashion I hope. Like the package C states on x86 -- for those to be effective the scheduler needs to pack tasks and keep entire packages idle for as long as possible. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
