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runtime: remove unused parfor code

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Change-Id: Ibbfae20cab48163f22d661604ef730705f2b97ba
Reviewed-on: https://go-review.googlesource.com/19661
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Austin Clements 2016-02-18 17:28:04 -05:00
parent 89cfdda44d
commit 8847a5913a
3 changed files with 0 additions and 381 deletions
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36
src/runtime/export_test.go
View File

@ -45,42 +45,6 @@ func LFStackPop(head *uint64) *LFNode {
return (*LFNode)(unsafe.Pointer(lfstackpop(head)))
}
type ParFor struct {
body func(*ParFor, uint32)
done uint32
Nthr uint32
thrseq uint32
Cnt uint32
wait bool
}
func NewParFor(nthrmax uint32) *ParFor {
var desc *ParFor
systemstack(func() {
desc = (*ParFor)(unsafe.Pointer(parforalloc(nthrmax)))
})
return desc
}
func ParForSetup(desc *ParFor, nthr, n uint32, wait bool, body func(*ParFor, uint32)) {
systemstack(func() {
parforsetup((*parfor)(unsafe.Pointer(desc)), nthr, n, wait,
*(*func(*parfor, uint32))(unsafe.Pointer(&body)))
})
}
func ParForDo(desc *ParFor) {
systemstack(func() {
parfordo((*parfor)(unsafe.Pointer(desc)))
})
}
func ParForIters(desc *ParFor, tid uint32) (uint32, uint32) {
desc1 := (*parfor)(unsafe.Pointer(desc))
pos := desc1.thr[tid].pos
return uint32(pos), uint32(pos >> 32)
}
func GCMask(x interface{}) (ret []byte) {
systemstack(func() {
ret = getgcmask(x)

217
src/runtime/parfor.go
View File

@ -1,217 +0,0 @@
// Copyright 2012 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.
// Parallel for algorithm.
package runtime
import (
"runtime/internal/atomic"
"runtime/internal/sys"
)
// A parfor holds state for the parallel for operation.
type parfor struct {
body func(*parfor, uint32) // executed for each element
done uint32 // number of idle threads
nthr uint32 // total number of threads
thrseq uint32 // thread id sequencer
cnt uint32 // iteration space [0, cnt)
wait bool // if true, wait while all threads finish processing,
// otherwise parfor may return while other threads are still working
thr []parforthread // thread descriptors
// stats
nsteal uint64
nstealcnt uint64
nprocyield uint64
nosyield uint64
nsleep uint64
}
// A parforthread holds state for a single thread in the parallel for.
type parforthread struct {
// the thread's iteration space [32lsb, 32msb)
pos uint64
// stats
nsteal uint64
nstealcnt uint64
nprocyield uint64
nosyield uint64
nsleep uint64
pad [sys.CacheLineSize]byte
}
func parforalloc(nthrmax uint32) *parfor {
return &parfor{
thr: make([]parforthread, nthrmax),
}
}
// Parforsetup initializes desc for a parallel for operation with nthr
// threads executing n jobs.
//
// On return the nthr threads are each expected to call parfordo(desc)
// to run the operation. During those calls, for each i in [0, n), one
// thread will be used invoke body(desc, i).
// If wait is true, no parfordo will return until all work has been completed.
// If wait is false, parfordo may return when there is a small amount
// of work left, under the assumption that another thread has that
// work well in hand.
func parforsetup(desc *parfor, nthr, n uint32, wait bool, body func(*parfor, uint32)) {
if desc == nil || nthr == 0 || nthr > uint32(len(desc.thr)) || body == nil {
print("desc=", desc, " nthr=", nthr, " count=", n, " body=", body, "\n")
throw("parfor: invalid args")
}
desc.body = body
desc.done = 0
desc.nthr = nthr
desc.thrseq = 0
desc.cnt = n
desc.wait = wait
desc.nsteal = 0
desc.nstealcnt = 0
desc.nprocyield = 0
desc.nosyield = 0
desc.nsleep = 0
for i := range desc.thr {
begin := uint32(uint64(n) * uint64(i) / uint64(nthr))
end := uint32(uint64(n) * uint64(i+1) / uint64(nthr))
desc.thr[i].pos = uint64(begin) | uint64(end)<<32
}
}
func parfordo(desc *parfor) {
// Obtain 0-based thread index.
tid := atomic.Xadd(&desc.thrseq, 1) - 1
if tid >= desc.nthr {
print("tid=", tid, " nthr=", desc.nthr, "\n")
throw("parfor: invalid tid")
}
// If single-threaded, just execute the for serially.
body := desc.body
if desc.nthr == 1 {
for i := uint32(0); i < desc.cnt; i++ {
body(desc, i)
}
return
}
me := &desc.thr[tid]
mypos := &me.pos
for {
for {
// While there is local work,
// bump low index and execute the iteration.
pos := atomic.Xadd64(mypos, 1)
begin := uint32(pos) - 1
end := uint32(pos >> 32)
if begin < end {
body(desc, begin)
continue
}
break
}
// Out of work, need to steal something.
idle := false
for try := uint32(0); ; try++ {
// If we don't see any work for long enough,
// increment the done counter...
if try > desc.nthr*4 && !idle {
idle = true
atomic.Xadd(&desc.done, 1)
}
// ...if all threads have incremented the counter,
// we are done.
extra := uint32(0)
if !idle {
extra = 1
}
if desc.done+extra == desc.nthr {
if !idle {
atomic.Xadd(&desc.done, 1)
}
goto exit
}
// Choose a random victim for stealing.
var begin, end uint32
victim := fastrand1() % (desc.nthr - 1)
if victim >= tid {
victim++
}
victimpos := &desc.thr[victim].pos
for {
// See if it has any work.
pos := atomic.Load64(victimpos)
begin = uint32(pos)
end = uint32(pos >> 32)
if begin+1 >= end {
end = 0
begin = end
break
}
if idle {
atomic.Xadd(&desc.done, -1)
idle = false
}
begin2 := begin + (end-begin)/2
newpos := uint64(begin) | uint64(begin2)<<32
if atomic.Cas64(victimpos, pos, newpos) {
begin = begin2
break
}
}
if begin < end {
// Has successfully stolen some work.
if idle {
throw("parfor: should not be idle")
}
atomic.Store64(mypos, uint64(begin)|uint64(end)<<32)
me.nsteal++
me.nstealcnt += uint64(end) - uint64(begin)
break
}
// Backoff.
if try < desc.nthr {
// nothing
} else if try < 4*desc.nthr {
me.nprocyield++
procyield(20)
} else if !desc.wait {
// If a caller asked not to wait for the others, exit now
// (assume that most work is already done at this point).
if !idle {
atomic.Xadd(&desc.done, 1)
}
goto exit
} else if try < 6*desc.nthr {
me.nosyield++
osyield()
} else {
me.nsleep++
usleep(1)
}
}
}
exit:
atomic.Xadd64(&desc.nsteal, int64(me.nsteal))
atomic.Xadd64(&desc.nstealcnt, int64(me.nstealcnt))
atomic.Xadd64(&desc.nprocyield, int64(me.nprocyield))
atomic.Xadd64(&desc.nosyield, int64(me.nosyield))
atomic.Xadd64(&desc.nsleep, int64(me.nsleep))
me.nsteal = 0
me.nstealcnt = 0
me.nprocyield = 0
me.nosyield = 0
me.nsleep = 0
}

128
src/runtime/parfor_test.go
View File

@ -1,128 +0,0 @@
// Copyright 2012 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.
// The race detector does not understand ParFor synchronization.
// +build !race
package runtime_test
import (
. "runtime"
"testing"
)
// Simple serial sanity test for parallelfor.
func TestParFor(t *testing.T) {
const P = 1
const N = 20
data := make([]uint64, N)
for i := uint64(0); i < N; i++ {
data[i] = i
}
desc := NewParFor(P)
ParForSetup(desc, P, N, true, func(desc *ParFor, i uint32) {
data[i] = data[i]*data[i] + 1
})
ParForDo(desc)
for i := uint64(0); i < N; i++ {
if data[i] != i*i+1 {
t.Fatalf("Wrong element %d: %d", i, data[i])
}
}
}
// Test that nonblocking parallelfor does not block.
func TestParFor2(t *testing.T) {
const P = 7
const N = 1003
data := make([]uint64, N)
for i := uint64(0); i < N; i++ {
data[i] = i
}
desc := NewParFor(P)
ParForSetup(desc, P, N, false, func(desc *ParFor, i uint32) {
data[i] = data[i]*data[i] + 1
})
for p := 0; p < P; p++ {
ParForDo(desc)
}
for i := uint64(0); i < N; i++ {
if data[i] != i*i+1 {
t.Fatalf("Wrong element %d: %d", i, data[i])
}
}
}
// Test that iterations are properly distributed.
func TestParForSetup(t *testing.T) {
const P = 11
const N = 101
desc := NewParFor(P)
for n := uint32(0); n < N; n++ {
for p := uint32(1); p <= P; p++ {
ParForSetup(desc, p, n, true, func(desc *ParFor, i uint32) {})
sum := uint32(0)
size0 := uint32(0)
end0 := uint32(0)
for i := uint32(0); i < p; i++ {
begin, end := ParForIters(desc, i)
size := end - begin
sum += size
if i == 0 {
size0 = size
if begin != 0 {
t.Fatalf("incorrect begin: %d (n=%d, p=%d)", begin, n, p)
}
} else {
if size != size0 && size != size0+1 {
t.Fatalf("incorrect size: %d/%d (n=%d, p=%d)", size, size0, n, p)
}
if begin != end0 {
t.Fatalf("incorrect begin/end: %d/%d (n=%d, p=%d)", begin, end0, n, p)
}
}
end0 = end
}
if sum != n {
t.Fatalf("incorrect sum: %d/%d (p=%d)", sum, n, p)
}
}
}
}
// Test parallel parallelfor.
func TestParForParallel(t *testing.T) {
N := uint64(1e7)
if testing.Short() {
N /= 10
}
data := make([]uint64, N)
for i := uint64(0); i < N; i++ {
data[i] = i
}
P := GOMAXPROCS(-1)
c := make(chan bool, P)
desc := NewParFor(uint32(P))
ParForSetup(desc, uint32(P), uint32(N), false, func(desc *ParFor, i uint32) {
data[i] = data[i]*data[i] + 1
})
for p := 1; p < P; p++ {
go func() {
ParForDo(desc)
c <- true
}()
}
ParForDo(desc)
for p := 1; p < P; p++ {
<-c
}
for i := uint64(0); i < N; i++ {
if data[i] != i*i+1 {
t.Fatalf("Wrong element %d: %d", i, data[i])
}
}
data, desc = nil, nil
GC()
}