diff --git a/lib/std/atomic.zig b/lib/std/atomic.zig index e1a6767590..5630bf6bf5 100644 --- a/lib/std/atomic.zig +++ b/lib/std/atomic.zig @@ -408,79 +408,87 @@ test spinLoopHint { } } +pub fn cacheLineForCpu(cpu: std.Target.Cpu) u16 { + return switch (cpu.arch) { + // x86_64: Starting from Intel's Sandy Bridge, the spatial prefetcher pulls in pairs of 64-byte cache lines at a time. + // - https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-optimization-manual.pdf + // - https://github.com/facebook/folly/blob/1b5288e6eea6df074758f877c849b6e73bbb9fbb/folly/lang/Align.h#L107 + // + // aarch64: Some big.LITTLE ARM archs have "big" cores with 128-byte cache lines: + // - https://www.mono-project.com/news/2016/09/12/arm64-icache/ + // - https://cpufun.substack.com/p/more-m1-fun-hardware-information + // + // - https://github.com/torvalds/linux/blob/3a7e02c040b130b5545e4b115aada7bacd80a2b6/arch/arc/Kconfig#L212 + // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_ppc64x.go#L9 + .x86_64, + .aarch64, + .aarch64_be, + .arc, + .powerpc64, + .powerpc64le, + => 128, + + // https://github.com/llvm/llvm-project/blob/e379094328e49731a606304f7e3559d4f1fa96f9/clang/lib/Basic/Targets/Hexagon.h#L145-L151 + .hexagon, + => if (std.Target.hexagon.featureSetHas(cpu.features, .v73)) 64 else 32, + + // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_arm.go#L7 + // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_mips.go#L7 + // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_mipsle.go#L7 + // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_mips64x.go#L9 + // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_riscv64.go#L7 + // - https://github.com/torvalds/linux/blob/3a7e02c040b130b5545e4b115aada7bacd80a2b6/arch/sparc/include/asm/cache.h#L14 + .arm, + .armeb, + .thumb, + .thumbeb, + .mips, + .mipsel, + .mips64, + .mips64el, + .riscv32, + .riscv64, + .sparc, + .sparc64, + => 32, + + // - https://github.com/torvalds/linux/blob/3a7e02c040b130b5545e4b115aada7bacd80a2b6/arch/m68k/include/asm/cache.h#L10 + .m68k, + => 16, + + // - https://www.ti.com/lit/pdf/slaa498 + .msp430, + => 8, + + // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_s390x.go#L7 + // - https://sxauroratsubasa.sakura.ne.jp/documents/guide/pdfs/Aurora_ISA_guide.pdf + .s390x, + .ve, + => 256, + + // Other x86 and WASM platforms have 64-byte cache lines. + // The rest of the architectures are assumed to be similar. + // - https://github.com/golang/go/blob/dda2991c2ea0c5914714469c4defc2562a907230/src/internal/cpu/cpu_x86.go#L9 + // - https://github.com/golang/go/blob/0a9321ad7f8c91e1b0c7184731257df923977eb9/src/internal/cpu/cpu_loong64.go#L11 + // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_wasm.go#L7 + // - https://github.com/torvalds/linux/blob/3a7e02c040b130b5545e4b115aada7bacd80a2b6/arch/xtensa/variants/csp/include/variant/core.h#L209 + // - https://github.com/torvalds/linux/blob/3a7e02c040b130b5545e4b115aada7bacd80a2b6/arch/csky/Kconfig#L183 + // - https://www.xmos.com/download/The-XMOS-XS3-Architecture.pdf + else => 64, + }; +} + /// The estimated size of the CPU's cache line when atomically updating memory. /// Add this much padding or align to this boundary to avoid atomically-updated /// memory from forcing cache invalidations on near, but non-atomic, memory. /// /// https://en.wikipedia.org/wiki/False_sharing /// https://github.com/golang/go/search?q=CacheLinePadSize -pub const cache_line = switch (builtin.cpu.arch) { - // x86_64: Starting from Intel's Sandy Bridge, the spatial prefetcher pulls in pairs of 64-byte cache lines at a time. - // - https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-optimization-manual.pdf - // - https://github.com/facebook/folly/blob/1b5288e6eea6df074758f877c849b6e73bbb9fbb/folly/lang/Align.h#L107 - // - // aarch64: Some big.LITTLE ARM archs have "big" cores with 128-byte cache lines: - // - https://www.mono-project.com/news/2016/09/12/arm64-icache/ - // - https://cpufun.substack.com/p/more-m1-fun-hardware-information - // - // - https://github.com/torvalds/linux/blob/3a7e02c040b130b5545e4b115aada7bacd80a2b6/arch/arc/Kconfig#L212 - // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_ppc64x.go#L9 - .x86_64, - .aarch64, - .aarch64_be, - .arc, - .powerpc64, - .powerpc64le, - => 128, +pub const cache_line = cacheLineForCpu(builtin.cpu); - // https://github.com/llvm/llvm-project/blob/e379094328e49731a606304f7e3559d4f1fa96f9/clang/lib/Basic/Targets/Hexagon.h#L145-L151 - .hexagon, - => if (std.Target.hexagon.featureSetHas(builtin.target.cpu.features, .v73)) 64 else 32, - - // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_arm.go#L7 - // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_mips.go#L7 - // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_mipsle.go#L7 - // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_mips64x.go#L9 - // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_riscv64.go#L7 - // - https://github.com/torvalds/linux/blob/3a7e02c040b130b5545e4b115aada7bacd80a2b6/arch/sparc/include/asm/cache.h#L14 - .arm, - .armeb, - .thumb, - .thumbeb, - .mips, - .mipsel, - .mips64, - .mips64el, - .riscv32, - .riscv64, - .sparc, - .sparc64, - => 32, - - // - https://github.com/torvalds/linux/blob/3a7e02c040b130b5545e4b115aada7bacd80a2b6/arch/m68k/include/asm/cache.h#L10 - .m68k, - => 16, - - // - https://www.ti.com/lit/pdf/slaa498 - .msp430, - => 8, - - // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_s390x.go#L7 - // - https://sxauroratsubasa.sakura.ne.jp/documents/guide/pdfs/Aurora_ISA_guide.pdf - .s390x, - .ve, - => 256, - - // Other x86 and WASM platforms have 64-byte cache lines. - // The rest of the architectures are assumed to be similar. - // - https://github.com/golang/go/blob/dda2991c2ea0c5914714469c4defc2562a907230/src/internal/cpu/cpu_x86.go#L9 - // - https://github.com/golang/go/blob/0a9321ad7f8c91e1b0c7184731257df923977eb9/src/internal/cpu/cpu_loong64.go#L11 - // - https://github.com/golang/go/blob/3dd58676054223962cd915bb0934d1f9f489d4d2/src/internal/cpu/cpu_wasm.go#L7 - // - https://github.com/torvalds/linux/blob/3a7e02c040b130b5545e4b115aada7bacd80a2b6/arch/xtensa/variants/csp/include/variant/core.h#L209 - // - https://github.com/torvalds/linux/blob/3a7e02c040b130b5545e4b115aada7bacd80a2b6/arch/csky/Kconfig#L183 - // - https://www.xmos.com/download/The-XMOS-XS3-Architecture.pdf - else => 64, -}; +test "current CPU has a cache line size" { + _ = cache_line; +} const std = @import("std.zig"); const builtin = @import("builtin");