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64 bytes, 512 bits.

Cachelines are 64 bytes on all modern hardware.

They will probably never change this value ever.

Everything fits into 64 bytes if you make the effort.

And if it doesn't you have to use two Arrays of 64 byte Structures and pad the last.

This is non negotiable and I'm completely baffled nobody has mentioned this yet.

I call this law: Ao64bS (did I invent my first law?) :D




It may be a language barrier thingy, but then we are talking about different things. Also, that is architecture dependent.


Nope on all modern CPUs (X86 and ARM) this is 64 bytes and has been since a looong time...


Cache lines are 128 bytes on M1.

But since it’s AMP and not SMP, sharing work across cores doesn’t necessarily work how you expect it to.


Can you ask the OS to give you a certain core type?

128 bytes is perfect 2 x 64! So even if the risk of cache invalidation goes up even if two cores are not writing to the exact same structure the alignment still works!

Good job Apple!


There absolutely are modern systems that have e.g. 128 byte cache lines (M1).




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