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runtime: using wyrand for fastrand

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For modern 64-bit CPU architecture multiplier is faster than xorshift

darwin/amd64
name              old time/op  new time/op  delta
Fastrand          2.13ns ± 1%  1.78ns ± 1%  -16.47%  (p=0.000 n=9+10)
FastrandHashiter  32.5ns ± 4%  32.1ns ± 3%     ~     (p=0.277 n=8+9)
Fastrandn/2       2.16ns ± 1%  1.99ns ± 1%   -7.53%  (p=0.000 n=10+10)
Fastrandn/3       2.13ns ± 3%  2.00ns ± 1%   -5.88%  (p=0.000 n=10+10)
Fastrandn/4       2.08ns ± 2%  1.98ns ± 2%   -4.71%  (p=0.000 n=10+10)
Fastrandn/5       2.08ns ± 2%  1.98ns ± 1%   -4.90%  (p=0.000 n=10+9)

linux/mips64le
name              old time/op  new time/op  delta
Fastrand          12.1ns ± 0%  10.8ns ± 1%  -10.58%  (p=0.000 n=8+10)
FastrandHashiter   105ns ± 1%   105ns ± 1%     ~     (p=0.138 n=10+10)
Fastrandn/2       16.9ns ± 0%  16.4ns ± 4%   -2.84%  (p=0.020 n=10+10)
Fastrandn/3       16.9ns ± 0%  16.4ns ± 3%   -3.03%  (p=0.000 n=10+10)
Fastrandn/4       16.9ns ± 0%  16.5ns ± 2%   -2.01%  (p=0.002 n=8+10)
Fastrandn/5       16.9ns ± 0%  16.4ns ± 3%   -2.70%  (p=0.000 n=8+10)

linux/riscv64
name              old time/op  new time/op  delta
Fastrand          22.7ns ± 0%  12.7ns ±19%  -44.09%  (p=0.000 n=9+10)
FastrandHashiter   255ns ± 4%   250ns ± 7%     ~     (p=0.363 n=10+10)
Fastrandn/2       31.8ns ± 2%  28.5ns ±13%  -10.45%  (p=0.000 n=10+10)
Fastrandn/3       33.0ns ± 2%  27.4ns ± 8%  -17.16%  (p=0.000 n=9+10)
Fastrandn/4       29.6ns ± 3%  28.2ns ± 5%   -4.81%  (p=0.000 n=8+9)
Fastrandn/5       33.4ns ± 3%  26.5ns ± 9%  -20.49%  (p=0.000 n=8+10)

Change-Id: I88ac69625ef923f8be66647e3361e3be986de002
Reviewed-on: https://go-review.googlesource.com/c/go/+/337350
Trust: Meng Zhuo <mzh@golangcn.org>
Run-TryBot: Meng Zhuo <mzh@golangcn.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Meng Zhuo 2021-09-14 10:48:18 +08:00
parent 0f1159bf54
commit 483533df9e
3 changed files with 20 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
src/runtime/proc.go
View File

@ -680,10 +680,10 @@ func schedinit() {
moduledataverify()
stackinit()
mallocinit()
cpuinit() // must run before alginit
alginit() // maps, hash, fastrand must not be used before this call
fastrandinit() // must run before mcommoninit
mcommoninit(_g_.m, -1)
cpuinit() // must run before alginit
alginit() // maps must not be used before this call
modulesinit() // provides activeModules
typelinksinit() // uses maps, activeModules
itabsinit() // uses activeModules
@ -787,11 +787,8 @@ func mcommoninit(mp *m, id int64) {
mp.id = mReserveID()
}
mp.fastrand[0] = uint32(int64Hash(uint64(mp.id), fastrandseed))
mp.fastrand[1] = uint32(int64Hash(uint64(cputicks()), ^fastrandseed))
if mp.fastrand[0]|mp.fastrand[1] == 0 {
mp.fastrand[1] = 1
}
// cputicks is not very random in startup virtual machine
mp.fastrand = uint64(int64Hash(uint64(mp.id), fastrandseed^uintptr(cputicks())))
mpreinit(mp)
if mp.gsignal != nil {

2
src/runtime/runtime2.go
View File

@ -538,7 +538,7 @@ type m struct {
printlock int8
incgo bool // m is executing a cgo call
freeWait uint32 // if == 0, safe to free g0 and delete m (atomic)
fastrand [2]uint32
fastrand uint64
needextram bool
traceback uint8
ncgocall uint64 // number of cgo calls in total

17
src/runtime/stubs.go
View File

@ -8,6 +8,7 @@ import (
"internal/abi"
"internal/goarch"
"internal/goexperiment"
"runtime/internal/math"
"unsafe"
)
@ -124,15 +125,27 @@ const hashLoad = float32(loadFactorNum) / float32(loadFactorDen)
//go:nosplit
func fastrand() uint32 {
mp := getg().m
// Implement wyrand: https://github.com/wangyi-fudan/wyhash
// Only the platform that math.Mul64 can be lowered
// by the compiler should be in this list.
if goarch.IsAmd64|goarch.IsArm64|goarch.IsPpc64|
goarch.IsPpc64le|goarch.IsMips64|goarch.IsMips64le|
goarch.IsS390x|goarch.IsRiscv64 == 1 {
mp.fastrand += 0xa0761d6478bd642f
hi, lo := math.Mul64(mp.fastrand, mp.fastrand^0xe7037ed1a0b428db)
return uint32(hi ^ lo)
}
// Implement xorshift64+: 2 32-bit xorshift sequences added together.
// Shift triplet [17,7,16] was calculated as indicated in Marsaglia's
// Xorshift paper: https://www.jstatsoft.org/article/view/v008i14/xorshift.pdf
// This generator passes the SmallCrush suite, part of TestU01 framework:
// http://simul.iro.umontreal.ca/testu01/tu01.html
s1, s0 := mp.fastrand[0], mp.fastrand[1]
t := (*[2]uint32)(unsafe.Pointer(&mp.fastrand))
s1, s0 := t[0], t[1]
s1 ^= s1 << 17
s1 = s1 ^ s0 ^ s1>>7 ^ s0>>16
mp.fastrand[0], mp.fastrand[1] = s0, s1
t[0], t[1] = s0, s1
return s0 + s1
}