Unhardcode alignas cache line size#15213
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…tive_interference_size This expands to __GCC_DESTRUCTIVE_SIZE, which is also 64 (at least in the x86_64 stdenv). Let the compiler decide what's the appropriate cache line size is. Also, on aarch64-darwin the cache line size 128 bytes, so the previous fix didn't actually get rid of false sharing reliably. Clang does this [1] [2], so it overestimates the sizes somewhat, but that's still enough for avoiding false sharing on darwin. [1]: https://github.com/llvm/llvm-project/blob/a289341dedf4d73955faefbb0b3c13881e13dd06/clang/lib/Frontend/InitPreprocessor.cpp#L1331-L1339 [2]: https://github.com/llvm/llvm-project/blob/6f51f8e0f93e6ff2baf0ed2f60021308920a557f/clang/lib/Basic/Targets/AArch64.h#L262-L264
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Motivation
This expands to __GCC_DESTRUCTIVE_SIZE, which is also 64 (at least in the x86_64 stdenv).
Let the compiler decide what's the appropriate cache line size is. Also, on aarch64-darwin
the cache line size 128 bytes, so the previous fix didn't actually get rid of false sharing
reliably. Clang does this 1 2, so it overestimates the sizes somewhat, but that's still enough
for avoiding false sharing on darwin.
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