From 150b728675c64addd24d79ad3bb68fec4c137940 Mon Sep 17 00:00:00 2001 From: Cherry Zhang Date: Wed, 14 Feb 2018 14:51:39 -0500 Subject: runtime: use native CAS and memory barrier on ARMv7 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This gets us around the kernel helpers on ARMv7. It is slightly faster than using the kernel helper. name old time/op new time/op delta AtomicLoad-4 72.5ns ± 0% 69.5ns ± 0% -4.08% (p=0.000 n=9+9) AtomicStore-4 57.6ns ± 1% 54.4ns ± 0% -5.58% (p=0.000 n=10+9) [Geo mean] 64.6ns 61.5ns -4.83% If performance is really critical, we can even do compiler intrinsics on GOARM=7. Fixes #23792. Change-Id: I36497d880890b26bdf01e048b542bd5fd7b17d23 Reviewed-on: https://go-review.googlesource.com/94076 Run-TryBot: Cherry Zhang TryBot-Result: Gobot Gobot Reviewed-by: Austin Clements --- src/runtime/internal/atomic/sys_linux_arm.s | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'src/runtime/internal/atomic/sys_linux_arm.s') diff --git a/src/runtime/internal/atomic/sys_linux_arm.s b/src/runtime/internal/atomic/sys_linux_arm.s index 60f28e7216..7e234d8f26 100644 --- a/src/runtime/internal/atomic/sys_linux_arm.s +++ b/src/runtime/internal/atomic/sys_linux_arm.s @@ -24,7 +24,14 @@ TEXT cas<>(SB),NOSPLIT,$0 MOVW $0xffff0fc0, R15 // R15 is hardware PC. -TEXT runtime∕internal∕atomic·Cas(SB),NOSPLIT,$0 +TEXT runtime∕internal∕atomic·Cas(SB),NOSPLIT|NOFRAME,$0 + MOVB runtime·goarm(SB), R11 + CMP $7, R11 + BLT 2(PC) + JMP ·armcas(SB) + JMP ·kernelcas<>(SB) + +TEXT runtime∕internal∕atomic·kernelcas<>(SB),NOSPLIT,$0 MOVW ptr+0(FP), R2 // trigger potential paging fault here, // because we don't know how to traceback through __kuser_cmpxchg -- cgit v1.3-5-g45d5