Messages in this thread | | | Date | Tue, 8 Mar 2022 20:21:41 +1100 | From | Paul Bone <> | Subject | Scheduling for heterogeneous computers |
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Are there plans for power-aware scheduling on heterogeneous computers that processes & threads can opt-in to?
Several mainstream devices now offer power-aware heterogeneous scheduling:
* Lots of ARM (and therefore android) devices offer big.LITTLE cores. * Apple's M1 CPU has "gold" and "silver" cores. The gold cores are faster and have more cache. I think there are other microarchitectual differences. * Intel's Alder Lake CPUs have P and E cores. I'm told that the E cores don't save power though since each core type still gets the same work done per Watt, it's just that the P cores are bigger and faster. * Multicore CPUs that offer frequency scaling could get some power savings by switching off turbo boost and similar features. They wonThe work/watt improves at the cost of throughput & responsiveness.
I'm aware that Linux does some Energy Aware Scheduling https://docs.kernel.org/scheduler/sched-energy.html, however what I'm looking for is an API that processes (but ideally threads) can opt in-to (and out-of (unlike nice)) to say that the work they're currently doing is bulk work. It needs to get done but it doesn't have a deadline and therefore can be done on a smaller / more power efficient core. The idea is that the same work gets done eventually, but for a background task (eg Garbage Collection) it can be done in a greener or more battery-charge-extending way.
MacOS has added an API for this as: pthread_set_qos_class_self_np() https://developer.apple.com/documentation/apple-silicon/tuning-your-code-s-performance-for-apple-silicon?preferredLanguage=occ
Windows has: ThreadPowerThrottling https://docs.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-setthreadinformation
I'm not aware of anything for Linux and I've been unable to find anything. Are there any plans to implement this?
Cheers.
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