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runtime: use vDSO clock_gettime on linux/mips64x

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Speed up nanotime1 and walltime1 on MIPS64 with vDSO, just like the
other vDSO-enabled targets.

Benchmark numbers on Loongson 3A3000 (GOARCH=mips64le, 1.4GHz) against
current master:

benchmark                old ns/op     new ns/op     delta
BenchmarkNow             868           293           -66.24%
BenchmarkNowUnixNano     851           296           -65.22%

Performance hit on fallback case, tested by using a wrong vDSO symbol name:

benchmark                old ns/op     new ns/op     delta
BenchmarkNow             868           889           +2.42%
BenchmarkNowUnixNano     851           893           +4.94%

Change-Id: Ibfb48893cd060536359863ffee7624c00def646b
GitHub-Last-Rev: 03a58ac2e4
GitHub-Pull-Request: golang/go#35181
Reviewed-on: https://go-review.googlesource.com/c/go/+/203578
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
This commit is contained in:
Wang Xuerui 2019-11-04 13:29:20 +00:00 committed by Brad Fitzpatrick
parent bf7e55b618
commit 210e3677f9
6 changed files with 107 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/runtime/os_linux_novdso.go
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@ -3,7 +3,7 @@
// license that can be found in the LICENSE file.
// +build linux
// +build !386,!amd64,!arm,!arm64,!ppc64,!ppc64le
// +build !386,!amd64,!arm,!arm64,!mips64,!mips64le,!ppc64,!ppc64le
package runtime

80
src/runtime/sys_linux_mips64x.s
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@ -211,23 +211,88 @@ TEXT runtime·mincore(SB),NOSPLIT|NOFRAME,$0-28
// func walltime1() (sec int64, nsec int32)
TEXT runtime·walltime1(SB),NOSPLIT,$16
MOVV R29, R16 // R16 is unchanged by C code
MOVV R29, R1
MOVV g_m(g), R17 // R17 = m
// Set vdsoPC and vdsoSP for SIGPROF traceback.
MOVV R31, m_vdsoPC(R17)
MOVV R29, m_vdsoSP(R17)
MOVV m_curg(R17), R4
MOVV g, R5
BNE R4, R5, noswitch
MOVV m_g0(R17), R4
MOVV (g_sched+gobuf_sp)(R4), R1 // Set SP to g0 stack
noswitch:
SUBV $16, R1
AND $~15, R1 // Align for C code
MOVV R1, R29
MOVW $0, R4 // CLOCK_REALTIME
MOVV $0(R29), R5
MOVV $SYS_clock_gettime, R2
SYSCALL
MOVV runtime·vdsoClockgettimeSym(SB), R25
BEQ R25, fallback
JAL (R25)
finish:
MOVV 0(R29), R3 // sec
MOVV 8(R29), R5 // nsec
MOVV R16, R29 // restore SP
MOVV R0, m_vdsoSP(R17) // clear vdsoSP
MOVV R3, sec+0(FP)
MOVW R5, nsec+8(FP)
RET
TEXT runtime·nanotime1(SB),NOSPLIT,$16
MOVW $1, R4 // CLOCK_MONOTONIC
MOVV $0(R29), R5
fallback:
MOVV $SYS_clock_gettime, R2
SYSCALL
JMP finish
TEXT runtime·nanotime1(SB),NOSPLIT,$16
MOVV R29, R16 // R16 is unchanged by C code
MOVV R29, R1
MOVV g_m(g), R17 // R17 = m
// Set vdsoPC and vdsoSP for SIGPROF traceback.
MOVV R31, m_vdsoPC(R17)
MOVV R29, m_vdsoSP(R17)
MOVV m_curg(R17), R4
MOVV g, R5
BNE R4, R5, noswitch
MOVV m_g0(R17), R4
MOVV (g_sched+gobuf_sp)(R4), R1 // Set SP to g0 stack
noswitch:
SUBV $16, R1
AND $~15, R1 // Align for C code
MOVV R1, R29
MOVW $1, R4 // CLOCK_MONOTONIC
MOVV $0(R29), R5
MOVV runtime·vdsoClockgettimeSym(SB), R25
BEQ R25, fallback
JAL (R25)
finish:
MOVV 0(R29), R3 // sec
MOVV 8(R29), R5 // nsec
MOVV R16, R29 // restore SP
MOVV R0, m_vdsoSP(R17) // clear vdsoSP
// sec is in R3, nsec in R5
// return nsec in R3
MOVV $1000000000, R4
@ -237,6 +302,11 @@ TEXT runtime·nanotime1(SB),NOSPLIT,$16
MOVV R3, ret+0(FP)
RET
fallback:
MOVV $SYS_clock_gettime, R2
SYSCALL
JMP finish
TEXT runtime·rtsigprocmask(SB),NOSPLIT|NOFRAME,$0-28
MOVW how+0(FP), R4
MOVV new+8(FP), R5

2
src/runtime/vdso_elf64.go
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@ -3,7 +3,7 @@
// license that can be found in the LICENSE file.
// +build linux
// +build amd64 arm64 ppc64 ppc64le
// +build amd64 arm64 mips64 mips64le ppc64 ppc64le
package runtime

2
src/runtime/vdso_in_none.go
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@ -2,7 +2,7 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build linux,!386,!amd64,!arm,!arm64,!ppc64,!ppc64le !linux
// +build linux,!386,!amd64,!arm,!arm64,!mips64,!mips64le,!ppc64,!ppc64le !linux
package runtime

2
src/runtime/vdso_linux.go
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@ -3,7 +3,7 @@
// license that can be found in the LICENSE file.
// +build linux
// +build 386 amd64 arm arm64 ppc64 ppc64le
// +build 386 amd64 arm arm64 mips64 mips64le ppc64 ppc64le
package runtime

28
src/runtime/vdso_linux_mips64x.go Normal file
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@ -0,0 +1,28 @@
// Copyright 2019 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.
// +build linux
// +build mips64 mips64le
package runtime
const (
// vdsoArrayMax is the byte-size of a maximally sized array on this architecture.
// See cmd/compile/internal/mips64/galign.go arch.MAXWIDTH initialization.
vdsoArrayMax = 1<<50 - 1
)
// see man 7 vdso : mips
var vdsoLinuxVersion = vdsoVersionKey{"LINUX_2.6", 0x3ae75f6}
// The symbol name is not __kernel_clock_gettime as suggested by the manpage;
// according to Linux source code it should be __vdso_clock_gettime instead.
var vdsoSymbolKeys = []vdsoSymbolKey{
{"__vdso_clock_gettime", 0xd35ec75, 0x6e43a318, &vdsoClockgettimeSym},
}
// initialize to fall back to syscall
var (
vdsoClockgettimeSym uintptr = 0
)