1 #![cfg_attr(not(feature = "sync"), allow(dead_code, unreachable_pub))] 2 use std::ops::{Deref, DerefMut}; 3 4 /// Pads and aligns a value to the length of a cache line. 5 #[derive(Clone, Copy, Default, Hash, PartialEq, Eq)] 6 // Starting from Intel's Sandy Bridge, spatial prefetcher is now pulling pairs of 64-byte cache 7 // lines at a time, so we have to align to 128 bytes rather than 64. 8 // 9 // Sources: 10 // - https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-optimization-manual.pdf 11 // - https://github.com/facebook/folly/blob/1b5288e6eea6df074758f877c849b6e73bbb9fbb/folly/lang/Align.h#L107 12 // 13 // ARM's big.LITTLE architecture has asymmetric cores and "big" cores have 128-byte cache line size. 14 // 15 // Sources: 16 // - https://www.mono-project.com/news/2016/09/12/arm64-icache/ 17 // 18 // powerpc64 has 128-byte cache line size. 19 // 20 // Sources: 21 // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_ppc64x.go#L9 22 #[cfg_attr( 23 any( 24 target_arch = "x86_64", 25 target_arch = "aarch64", 26 target_arch = "powerpc64", 27 ), 28 repr(align(128)) 29 )] 30 // arm, mips, mips64, and riscv64 have 32-byte cache line size. 31 // 32 // Sources: 33 // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_arm.go#L7 34 // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_mips.go#L7 35 // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_mipsle.go#L7 36 // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_mips64x.go#L9 37 // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_riscv64.go#L7 38 #[cfg_attr( 39 any( 40 target_arch = "arm", 41 target_arch = "mips", 42 target_arch = "mips64", 43 target_arch = "riscv64", 44 ), 45 repr(align(32)) 46 )] 47 // s390x has 256-byte cache line size. 48 // 49 // Sources: 50 // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_s390x.go#L7 51 #[cfg_attr(target_arch = "s390x", repr(align(256)))] 52 // x86 and wasm have 64-byte cache line size. 53 // 54 // Sources: 55 // - https://github.com/golang/go/blob/dda2991c2ea0c5914714469c4defc2562a907230/src/internal/cpu/cpu_x86.go#L9 56 // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_wasm.go#L7 57 // 58 // All others are assumed to have 64-byte cache line size. 59 #[cfg_attr( 60 not(any( 61 target_arch = "x86_64", 62 target_arch = "aarch64", 63 target_arch = "powerpc64", 64 target_arch = "arm", 65 target_arch = "mips", 66 target_arch = "mips64", 67 target_arch = "riscv64", 68 target_arch = "s390x", 69 )), 70 repr(align(64)) 71 )] 72 pub(crate) struct CachePadded<T> { 73 value: T, 74 } 75 76 impl<T> CachePadded<T> { 77 /// Pads and aligns a value to the length of a cache line. new(value: T) -> CachePadded<T>78 pub(crate) fn new(value: T) -> CachePadded<T> { 79 CachePadded::<T> { value } 80 } 81 } 82 83 impl<T> Deref for CachePadded<T> { 84 type Target = T; 85 deref(&self) -> &T86 fn deref(&self) -> &T { 87 &self.value 88 } 89 } 90 91 impl<T> DerefMut for CachePadded<T> { deref_mut(&mut self) -> &mut T92 fn deref_mut(&mut self) -> &mut T { 93 &mut self.value 94 } 95 } 96