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runtime: convert schedt.nmspinning to atomic type

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Note that this converts nmspinning from uint32 to int32 for consistency
with the other count fields in schedt.

For #53821.

Change-Id: Ia6ca7a2b476128eda3b68e9f0c7775ae66c0c744
Reviewed-on: https://go-review.googlesource.com/c/go/+/419446
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Michael Pratt <mpratt@google.com>
Reviewed-by: Austin Clements <austin@google.com>
This commit is contained in:
Michael Pratt 2022-07-25 15:20:22 -04:00
parent 58a1dabfd1
commit 1eeef5d5b4
3 changed files with 18 additions and 18 deletions
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2
src/runtime/mgcpacer.go
View file

@ -750,7 +750,7 @@ func (c *gcControllerState) enlistWorker() {
// If there are idle Ps, wake one so it will run an idle worker. // If there are idle Ps, wake one so it will run an idle worker.
// NOTE: This is suspected of causing deadlocks. See golang.org/issue/19112. // NOTE: This is suspected of causing deadlocks. See golang.org/issue/19112.
// //
// if sched.npidle.Load() != 0 && atomic.Load(&sched.nmspinning) == 0 { // if sched.npidle.Load() != 0 && sched.nmspinning.Load() == 0 {
// wakep() // wakep()
// return // return
// } // }

32
src/runtime/proc.go
View file

@ -2282,7 +2282,7 @@ func startm(pp *p, spinning bool) {
if spinning { if spinning {
// The caller incremented nmspinning, but there are no idle Ps, // The caller incremented nmspinning, but there are no idle Ps,
// so it's okay to just undo the increment and give up. // so it's okay to just undo the increment and give up.
if int32(atomic.Xadd(&sched.nmspinning, -1)) < 0 { if sched.nmspinning.Add(-1) < 0 {
throw("startm: negative nmspinning") throw("startm: negative nmspinning")
} }
} }
@ -2362,7 +2362,7 @@ func handoffp(pp *p) {
} }
// no local work, check that there are no spinning/idle M's, // no local work, check that there are no spinning/idle M's,
// otherwise our help is not required // otherwise our help is not required
if int32(atomic.Load(&sched.nmspinning))+sched.npidle.Load() == 0 && atomic.Cas(&sched.nmspinning, 0, 1) { // TODO: fast atomic if sched.nmspinning.Load()+sched.npidle.Load() == 0 && sched.nmspinning.CompareAndSwap(0, 1) { // TODO: fast atomic
startm(pp, true) startm(pp, true)
return return
} }
@ -2414,7 +2414,7 @@ func wakep() {
return return
} }
// be conservative about spinning threads // be conservative about spinning threads
if atomic.Load(&sched.nmspinning) != 0 || !atomic.Cas(&sched.nmspinning, 0, 1) { if sched.nmspinning.Load() != 0 || !sched.nmspinning.CompareAndSwap(0, 1) {
return return
} }
startm(nil, true) startm(nil, true)
@ -2478,7 +2478,7 @@ func gcstopm() {
gp.m.spinning = false gp.m.spinning = false
// OK to just drop nmspinning here, // OK to just drop nmspinning here,
// startTheWorld will unpark threads as necessary. // startTheWorld will unpark threads as necessary.
if int32(atomic.Xadd(&sched.nmspinning, -1)) < 0 { if sched.nmspinning.Add(-1) < 0 {
throw("gcstopm: negative nmspinning") throw("gcstopm: negative nmspinning")
} }
} }
@ -2649,10 +2649,10 @@ top:
// Limit the number of spinning Ms to half the number of busy Ps. // Limit the number of spinning Ms to half the number of busy Ps.
// This is necessary to prevent excessive CPU consumption when // This is necessary to prevent excessive CPU consumption when
// GOMAXPROCS>>1 but the program parallelism is low. // GOMAXPROCS>>1 but the program parallelism is low.
if mp.spinning || int32(2*atomic.Load(&sched.nmspinning)) < gomaxprocs-sched.npidle.Load() { if mp.spinning || 2*sched.nmspinning.Load() < gomaxprocs-sched.npidle.Load() {
if !mp.spinning { if !mp.spinning {
mp.spinning = true mp.spinning = true
atomic.Xadd(&sched.nmspinning, 1) sched.nmspinning.Add(1)
} }
gp, inheritTime, tnow, w, newWork := stealWork(now) gp, inheritTime, tnow, w, newWork := stealWork(now)
@ -2757,7 +2757,7 @@ top:
wasSpinning := mp.spinning wasSpinning := mp.spinning
if mp.spinning { if mp.spinning {
mp.spinning = false mp.spinning = false
if int32(atomic.Xadd(&sched.nmspinning, -1)) < 0 { if sched.nmspinning.Add(-1) < 0 {
throw("findrunnable: negative nmspinning") throw("findrunnable: negative nmspinning")
} }
@ -2772,7 +2772,7 @@ top:
if pp != nil { if pp != nil {
acquirep(pp) acquirep(pp)
mp.spinning = true mp.spinning = true
atomic.Xadd(&sched.nmspinning, 1) sched.nmspinning.Add(1)
goto top goto top
} }
@ -2781,7 +2781,7 @@ top:
if pp != nil { if pp != nil {
acquirep(pp) acquirep(pp)
mp.spinning = true mp.spinning = true
atomic.Xadd(&sched.nmspinning, 1) sched.nmspinning.Add(1)
// Run the idle worker. // Run the idle worker.
pp.gcMarkWorkerMode = gcMarkWorkerIdleMode pp.gcMarkWorkerMode = gcMarkWorkerIdleMode
@ -2850,7 +2850,7 @@ top:
} }
if wasSpinning { if wasSpinning {
mp.spinning = true mp.spinning = true
atomic.Xadd(&sched.nmspinning, 1) sched.nmspinning.Add(1)
} }
goto top goto top
} }
@ -3089,8 +3089,8 @@ func resetspinning() {
throw("resetspinning: not a spinning m") throw("resetspinning: not a spinning m")
} }
gp.m.spinning = false gp.m.spinning = false
nmspinning := atomic.Xadd(&sched.nmspinning, -1) nmspinning := sched.nmspinning.Add(-1)
if int32(nmspinning) < 0 { if nmspinning < 0 {
throw("findrunnable: negative nmspinning") throw("findrunnable: negative nmspinning")
} }
// M wakeup policy is deliberately somewhat conservative, so check if we // M wakeup policy is deliberately somewhat conservative, so check if we
@ -5085,7 +5085,7 @@ func checkdead() {
// M must be spinning to steal. We set this to be // M must be spinning to steal. We set this to be
// explicit, but since this is the only M it would // explicit, but since this is the only M it would
// become spinning on its own anyways. // become spinning on its own anyways.
atomic.Xadd(&sched.nmspinning, 1) sched.nmspinning.Add(1)
mp.spinning = true mp.spinning = true
mp.nextp.set(pp) mp.nextp.set(pp)
notewakeup(&mp.park) notewakeup(&mp.park)
@ -5317,7 +5317,7 @@ func retake(now int64) uint32 {
// On the one hand we don't want to retake Ps if there is no other work to do, // On the one hand we don't want to retake Ps if there is no other work to do,
// but on the other hand we want to retake them eventually // but on the other hand we want to retake them eventually
// because they can prevent the sysmon thread from deep sleep. // because they can prevent the sysmon thread from deep sleep.
if runqempty(pp) && atomic.Load(&sched.nmspinning)+uint32(sched.npidle.Load()) > 0 && pd.syscallwhen+10*1000*1000 > now { if runqempty(pp) && sched.nmspinning.Load()+sched.npidle.Load() > 0 && pd.syscallwhen+10*1000*1000 > now {
continue continue
} }
// Drop allpLock so we can take sched.lock. // Drop allpLock so we can take sched.lock.
@ -5408,7 +5408,7 @@ func schedtrace(detailed bool) {
} }
lock(&sched.lock) lock(&sched.lock)
print("SCHED ", (now-starttime)/1e6, "ms: gomaxprocs=", gomaxprocs, " idleprocs=", sched.npidle.Load(), " threads=", mcount(), " spinningthreads=", sched.nmspinning, " idlethreads=", sched.nmidle, " runqueue=", sched.runqsize) print("SCHED ", (now-starttime)/1e6, "ms: gomaxprocs=", gomaxprocs, " idleprocs=", sched.npidle.Load(), " threads=", mcount(), " spinningthreads=", sched.nmspinning.Load(), " idlethreads=", sched.nmidle, " runqueue=", sched.runqsize)
if detailed { if detailed {
print(" gcwaiting=", sched.gcwaiting, " nmidlelocked=", sched.nmidlelocked, " stopwait=", sched.stopwait, " sysmonwait=", sched.sysmonwait, "\n") print(" gcwaiting=", sched.gcwaiting, " nmidlelocked=", sched.nmidlelocked, " stopwait=", sched.stopwait, " sysmonwait=", sched.sysmonwait, "\n")
} }
@ -6193,7 +6193,7 @@ func sync_runtime_canSpin(i int) bool {
// GOMAXPROCS>1 and there is at least one other running P and local runq is empty. // GOMAXPROCS>1 and there is at least one other running P and local runq is empty.
// As opposed to runtime mutex we don't do passive spinning here, // As opposed to runtime mutex we don't do passive spinning here,
// because there can be work on global runq or on other Ps. // because there can be work on global runq or on other Ps.
if i >= active_spin || ncpu <= 1 || gomaxprocs <= sched.npidle.Load()+int32(sched.nmspinning)+1 { if i >= active_spin || ncpu <= 1 || gomaxprocs <= sched.npidle.Load()+sched.nmspinning.Load()+1 {
return false return false
} }
if p := getg().m.p.ptr(); !runqempty(p) { if p := getg().m.p.ptr(); !runqempty(p) {

2
src/runtime/runtime2.go
View file

@ -779,7 +779,7 @@ type schedt struct {
pidle puintptr // idle p's pidle puintptr // idle p's
npidle atomic.Int32 npidle atomic.Int32
nmspinning uint32 // See "Worker thread parking/unparking" comment in proc.go. nmspinning atomic.Int32 // See "Worker thread parking/unparking" comment in proc.go.
// Global runnable queue. // Global runnable queue.
runq gQueue runq gQueue