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Interesting, enjoyable read. The conclusions seem a bit off though -Low QoS tasks are limited to certain cores. This doesn't necessitate efficiency cores (tho
by defaultname 5y ago
Interesting, enjoyable read.
The conclusions seem a bit off though
-Low QoS tasks are limited to certain cores. This doesn't necessitate efficiency cores (though it makes sense if you want power efficiency in a mobile configuration) and they could as easily be performance cores. The core facet is that the OS has core affinity for low priority tasks and quarantines them to a subset of cores. And it has properly configured low priority tasks as such.
-It also has nothing to do with ARM (as the original title surmised). It's all in the operating system and, again, core affinity. Windows can do this on Intel. macOS/iOS has heavily pushed priorities as meaningful and important, so now with the inclusion of efficiency cores they have established their ecosystem to be able to use it widely.
- lupire 5y agoIf it has nothing to do with ARM, why doesn't Mac do it at similar speed on Intel?
- defaultname 5y agoThe focus of the linked article is responsiveness/user interaction, attributing that to efficiency cores. Apple can achieve exactly the same responsiveness benefit on their Intel devices by, as mentioned, limiting low priority tasks to a subset of cores. Say 2 of 6 real cores on a MBP with an i7. Apple actually pushes low priority tasks to the efficiency cores for power efficiency reasons (per the name), not user responsiveness. So that MBP runs for longer, cooler on a battery because things that can take longer run on more efficient, slower cores. They do the same with the efficiency cores on modern iOS devices. The "feeling faster" is a side effect. I am talking about that side effect which isn't ARM specific. And FWIW, Intel is adding efficiency/"little" cores to their upcoming architectures. Again for efficiency reasons.
- bombcar 5y agoThere's no point in shuffling background processes to a subset of cores if it doesn't provide power-savings. It sounds like upcoming Intel chips will have the ability to run efficiency-mode on some cores, at which case OS-level code to do shuffling makes sense.
- fomine3 5y agoBecause there are no Intel Mac with heterogeneous cores. Lakefield is first CPU with LITTLE cores, but not available for mac.