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On an android device I worked on some 5 years ago (so might be out of date) it used a simple cpu mask. Background tasks always used only the little cores, fore
by kimixa 4y ago
On an android device I worked on some 5 years ago (so might be out of date) it used a simple cpu mask.
Background tasks always used only the little cores, foreground apps always always used only the big cores. I do not believe it was possible for a single app to run threads on both big and little cores.
And my understanding is that every arm big.LITTLE combination supported exactly the same ISA and were intentionally 100% binary compatible. For example, you couldn't pair arm A53 little cores (that support only armv8-a) with A75 big cores (which support armv8.2-a)
- londons_explore 4y agoWith some software work, you could pair differing cores. You'd just deliver a signal to a process saying 'youre about to be moved to a different core type, please recheck the capabilities'. Then, you'd have a compatibility shim that emulates unimplemented instructions using traps for software that hadn't yet been rewritten to understand the above signal.
- justincormack 4y agoThere were s small number of phones shipped with differing cores but it did not work well.