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runtime: use vDSO clock_gettime on linux/riscv64

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Speed up nanotime1 and walltime on riscv64 with vDSO, just like the
other vDSO-enabled targets.

name          old time/op  new time/op  delta
Now           1.53µs ± 1%  1.05µs ± 3%  -31.74%  (p=0.000 n=10+10)
NowUnixNano   1.54µs ± 0%  1.05µs ± 2%  -31.91%  (p=0.000 n=9+10)
NowUnixMilli  1.56µs ± 1%  1.06µs ± 1%  -31.73%  (p=0.000 n=10+10)
NowUnixMicro  1.56µs ± 1%  1.05µs ± 1%  -32.80%  (p=0.000 n=9+10)

Change-Id: I69b3fe3cc57685a826c53b366c0992e8048399bb
Reviewed-on: https://go-review.googlesource.com/c/go/+/328509
Trust: Meng Zhuo <mzh@golangcn.org>
Run-TryBot: Meng Zhuo <mzh@golangcn.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This commit is contained in:
Meng Zhuo 2021-08-26 09:32:38 +08:00
parent df4c625d88
commit 1bd35fab05
7 changed files with 159 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
src/runtime/os_linux_novdso.go
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@ -2,8 +2,8 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build linux && !386 && !amd64 && !arm && !arm64 && !mips64 && !mips64le && !ppc64 && !ppc64le
// +build linux,!386,!amd64,!arm,!arm64,!mips64,!mips64le,!ppc64,!ppc64le
//go:build linux && !386 && !amd64 && !arm && !arm64 && !mips64 && !mips64le && !ppc64 && !ppc64le && !riscv64
// +build linux,!386,!amd64,!arm,!arm64,!mips64,!mips64le,!ppc64,!ppc64le,!riscv64
package runtime

2
src/runtime/signal_unix.go
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@ -383,7 +383,7 @@ func preemptM(mp *m) {
//go:nosplit
func sigFetchG(c *sigctxt) *g {
switch GOARCH {
case "arm", "arm64", "ppc64", "ppc64le":
case "arm", "arm64", "ppc64", "ppc64le", "riscv64":
if !iscgo && inVDSOPage(c.sigpc()) {
// When using cgo, we save the g on TLS and load it from there
// in sigtramp. Just use that.

135
src/runtime/sys_linux_riscv64.s
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@ -10,6 +10,8 @@
#include "go_asm.h"
#define AT_FDCWD -100
#define CLOCK_REALTIME 0
#define CLOCK_MONOTONIC 1
#define SYS_brk 214
#define SYS_clock_gettime 113
@ -210,8 +212,68 @@ TEXT runtime·mincore(SB),NOSPLIT|NOFRAME,$0-28
RET
// func walltime() (sec int64, nsec int32)
TEXT runtime·walltime(SB),NOSPLIT,$24-12
MOV $0, A0 // CLOCK_REALTIME
TEXT runtime·walltime(SB),NOSPLIT,$40-12
MOV $CLOCK_REALTIME, A0
MOV runtime·vdsoClockgettimeSym(SB), A7
BEQZ A7, fallback
MOV X2, S2 // S2,S3,S4 is unchanged by C code
MOV g_m(g), S3 // S3 = m
// Save the old values on stack for reentrant
MOV m_vdsoPC(S3), T0
MOV T0, 24(X2)
MOV m_vdsoSP(S3), T0
MOV T0, 32(X2)
MOV RA, m_vdsoPC(S3)
MOV $ret-8(FP), T1 // caller's SP
MOV T1, m_vdsoSP(S3)
MOV m_curg(S3), T1
BNE g, T1, noswitch
MOV m_g0(S3), T1
MOV (g_sched+gobuf_sp)(T1), X2
noswitch:
ADDI $-24, X2 // Space for result
ANDI $~7, X2 // Align for C code
MOV $8(X2), A1
// Store g on gsignal's stack, see sys_linux_arm64.s for detail
MOVBU runtime·iscgo(SB), S4
BNEZ S4, nosaveg
MOV m_gsignal(S3), S4 // g.m.gsignal
BEQZ S4, nosaveg
BEQ g, S4, nosaveg
MOV (g_stack+stack_lo)(S4), S4 // g.m.gsignal.stack.lo
MOV g, (S4)
JALR RA, A7
MOV ZERO, (S4)
JMP finish
nosaveg:
JALR RA, A7
finish:
MOV 8(X2), T0 // sec
MOV 16(X2), T1 // nsec
MOV S2, X2 // restore stack
MOV 24(X2), A2
MOV A2, m_vdsoPC(S3)
MOV 32(X2), A3
MOV A3, m_vdsoSP(S3)
MOV T0, sec+0(FP)
MOVW T1, nsec+8(FP)
RET
fallback:
MOV $8(X2), A1
MOV $SYS_clock_gettime, A7
ECALL
@ -222,15 +284,76 @@ TEXT runtime·walltime(SB),NOSPLIT,$24-12
RET
// func nanotime1() int64
TEXT runtime·nanotime1(SB),NOSPLIT,$24-8
MOV $1, A0 // CLOCK_MONOTONIC
TEXT runtime·nanotime1(SB),NOSPLIT,$40-8
MOV $CLOCK_MONOTONIC, A0
MOV runtime·vdsoClockgettimeSym(SB), A7
BEQZ A7, fallback
MOV X2, S2 // S2 = RSP, S2 is unchanged by C code
MOV g_m(g), S3 // S3 = m
// Save the old values on stack for reentrant
MOV m_vdsoPC(S3), T0
MOV T0, 24(X2)
MOV m_vdsoSP(S3), T0
MOV T0, 32(X2)
MOV RA, m_vdsoPC(S3)
MOV $ret-8(FP), T0 // caller's SP
MOV T0, m_vdsoSP(S3)
MOV m_curg(S3), T1
BNE g, T1, noswitch
MOV m_g0(S3), T1
MOV (g_sched+gobuf_sp)(T1), X2
noswitch:
ADDI $-24, X2 // Space for result
ANDI $~7, X2 // Align for C code
MOV $8(X2), A1
// Store g on gsignal's stack, see sys_linux_arm64.s for detail
MOVBU runtime·iscgo(SB), S4
BNEZ S4, nosaveg
MOV m_gsignal(S3), S4 // g.m.gsignal
BEQZ S4, nosaveg
BEQ g, S4, nosaveg
MOV (g_stack+stack_lo)(S4), S4 // g.m.gsignal.stack.lo
MOV g, (S4)
JALR RA, A7
MOV ZERO, (S4)
JMP finish
nosaveg:
JALR RA, A7
finish:
MOV 8(X2), T0 // sec
MOV 16(X2), T1 // nsec
// restore stack
MOV S2, X2
MOV 24(X2), T2
MOV T2, m_vdsoPC(S3)
MOV 32(X2), T2
MOV T2, m_vdsoSP(S3)
// sec is in T0, nsec in T1
// return nsec in T0
MOV $1000000000, T2
MUL T2, T0
ADD T1, T0
MOV T0, ret+0(FP)
RET
fallback:
MOV $8(X2), A1
MOV $SYS_clock_gettime, A7
ECALL
MOV 8(X2), T0 // sec
MOV 16(X2), T1 // nsec
// sec is in T0, nsec in T1
// return nsec in T0
MOV $1000000000, T2
MUL T2, T0
ADD T1, T0

4
src/runtime/vdso_elf64.go
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@ -2,9 +2,9 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build linux && (amd64 || arm64 || mips64 || mips64le || ppc64 || ppc64le)
//go:build linux && (amd64 || arm64 || mips64 || mips64le || ppc64 || ppc64le || riscv64)
// +build linux
// +build amd64 arm64 mips64 mips64le ppc64 ppc64le
// +build amd64 arm64 mips64 mips64le ppc64 ppc64le riscv64
package runtime

4
src/runtime/vdso_in_none.go
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@ -2,8 +2,8 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build (linux && !386 && !amd64 && !arm && !arm64 && !mips64 && !mips64le && !ppc64 && !ppc64le) || !linux
// +build linux,!386,!amd64,!arm,!arm64,!mips64,!mips64le,!ppc64,!ppc64le !linux
//go:build (linux && !386 && !amd64 && !arm && !arm64 && !mips64 && !mips64le && !ppc64 && !ppc64le && !riscv64) || !linux
// +build linux,!386,!amd64,!arm,!arm64,!mips64,!mips64le,!ppc64,!ppc64le,!riscv64 !linux
package runtime

4
src/runtime/vdso_linux.go
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@ -2,9 +2,9 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build linux && (386 || amd64 || arm || arm64 || mips64 || mips64le || ppc64 || ppc64le)
//go:build linux && (386 || amd64 || arm || arm64 || mips64 || mips64le || ppc64 || ppc64le || riscv64)
// +build linux
// +build 386 amd64 arm arm64 mips64 mips64le ppc64 ppc64le
// +build 386 amd64 arm arm64 mips64 mips64le ppc64 ppc64le riscv64
package runtime

21
src/runtime/vdso_linux_riscv64.go Normal file
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@ -0,0 +1,21 @@
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package runtime
const (
// vdsoArrayMax is the byte-size of a maximally sized array on this architecture.
// See cmd/compile/internal/riscv64/galign.go arch.MAXWIDTH initialization.
vdsoArrayMax = 1<<50 - 1
)
// key and version at man 7 vdso : riscv
var vdsoLinuxVersion = vdsoVersionKey{"LINUX_4.15", 0xae77f75}
var vdsoSymbolKeys = []vdsoSymbolKey{
{"__vdso_clock_gettime", 0xd35ec75, 0x6e43a318, &vdsoClockgettimeSym},
}
// initialize to fall back to syscall
var vdsoClockgettimeSym uintptr = 0