What is the cache line size on iPhone and iPad?
And does it vary much between the different devices and CPUs? This is not too easy to find with google.
I need to squeeze some extra performance from my app. :)
Well, the Cortex-A8 has 64-byte lines, Cortex-A9 has 32-byte lines, as for Swift and Cyclone I don't know - looking at comparable cores (A15, A57, Scorpion, Krait) 32 or 64 bytes seems likely. Either way there's at least 2 different lengths across iOS7 machines.
As you're performance-focused though, remember that benchmarking is infinitely more valuable than theorising - try as many reasonable combinations of code on every piece of hardware you can lay your hands on, go with what's fastest in practice regardless of what 'should' be best.
来源：https://stackoverflow.com/questions/22132821/what-is-the-cache-line-size-on-iphone-and-ipad