runtime: convert schedt.nmspinning to atomic type

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>

diff --git a/src/runtime/mgcpacer.go b/src/runtime/mgcpacer.go
index 9e12e4c8dbf5608628e57f5a60f5e9fc1ecf7cc4..f73a3a827700f1a351bdc4957fc46354a72cccb1 100644 (file)
--- a/src/runtime/mgcpacer.go
+++ b/src/runtime/mgcpacer.go
@@ -750,7 +750,7 @@ func (c *gcControllerState) enlistWorker() {
        // 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.
        //
-       //      if sched.npidle.Load() != 0 && atomic.Load(&sched.nmspinning) == 0 {
+       //      if sched.npidle.Load() != 0 && sched.nmspinning.Load() == 0 {
        //              wakep()
        //              return
        //      }

diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index 9cad2161b55cf15896d879e80b2e6421b8929b67..a7d60a024a977b31fb408a85a7241d6c23111386 100644 (file)
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -2282,7 +2282,7 @@ func startm(pp *p, spinning bool) {
                        if spinning {
                                // The caller incremented nmspinning, but there are no idle Ps,
                                // 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")
                                }
                        }
@@ -2362,7 +2362,7 @@ func handoffp(pp *p) {
        }
        // no local work, check that there are no spinning/idle M's,
        // 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)
                return
        }
@@ -2414,7 +2414,7 @@ func wakep() {
                return
        }
        // 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
        }
        startm(nil, true)
@@ -2478,7 +2478,7 @@ func gcstopm() {
                gp.m.spinning = false
                // OK to just drop nmspinning here,
                // startTheWorld will unpark threads as necessary.
-               if int32(atomic.Xadd(&sched.nmspinning, -1)) < 0 {
+               if sched.nmspinning.Add(-1) < 0 {
                        throw("gcstopm: negative nmspinning")
                }
        }
@@ -2649,10 +2649,10 @@ top:
        // Limit the number of spinning Ms to half the number of busy Ps.
        // This is necessary to prevent excessive CPU consumption when
        // 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 {
                        mp.spinning = true
-                       atomic.Xadd(&sched.nmspinning, 1)
+                       sched.nmspinning.Add(1)
                }
 
                gp, inheritTime, tnow, w, newWork := stealWork(now)
@@ -2757,7 +2757,7 @@ top:
        wasSpinning := mp.spinning
        if mp.spinning {
                mp.spinning = false
-               if int32(atomic.Xadd(&sched.nmspinning, -1)) < 0 {
+               if sched.nmspinning.Add(-1) < 0 {
                        throw("findrunnable: negative nmspinning")
                }
 
@@ -2772,7 +2772,7 @@ top:
                if pp != nil {
                        acquirep(pp)
                        mp.spinning = true
-                       atomic.Xadd(&sched.nmspinning, 1)
+                       sched.nmspinning.Add(1)
                        goto top
                }
 
@@ -2781,7 +2781,7 @@ top:
                if pp != nil {
                        acquirep(pp)
                        mp.spinning = true
-                       atomic.Xadd(&sched.nmspinning, 1)
+                       sched.nmspinning.Add(1)
 
                        // Run the idle worker.
                        pp.gcMarkWorkerMode = gcMarkWorkerIdleMode
@@ -2850,7 +2850,7 @@ top:
                        }
                        if wasSpinning {
                                mp.spinning = true
-                               atomic.Xadd(&sched.nmspinning, 1)
+                               sched.nmspinning.Add(1)
                        }
                        goto top
                }
@@ -3089,8 +3089,8 @@ func resetspinning() {
                throw("resetspinning: not a spinning m")
        }
        gp.m.spinning = false
-       nmspinning := atomic.Xadd(&sched.nmspinning, -1)
-       if int32(nmspinning) < 0 {
+       nmspinning := sched.nmspinning.Add(-1)
+       if nmspinning < 0 {
                throw("findrunnable: negative nmspinning")
        }
        // 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
                        // explicit, but since this is the only M it would
                        // become spinning on its own anyways.
-                       atomic.Xadd(&sched.nmspinning, 1)
+                       sched.nmspinning.Add(1)
                        mp.spinning = true
                        mp.nextp.set(pp)
                        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,
                        // but on the other hand we want to retake them eventually
                        // 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
                        }
                        // Drop allpLock so we can take sched.lock.
@@ -5408,7 +5408,7 @@ func schedtrace(detailed bool) {
        }
 
        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 {
                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.
        // As opposed to runtime mutex we don't do passive spinning here,
        // 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
        }
        if p := getg().m.p.ptr(); !runqempty(p) {

diff --git a/src/runtime/runtime2.go b/src/runtime/runtime2.go
index 7b43358ba1cbc9e8457049e7dd83da727f75da81..bf1b53cb124fc089d7fc3b11d8d41e77f917f8ea 100644 (file)
--- a/src/runtime/runtime2.go
+++ b/src/runtime/runtime2.go
@@ -779,7 +779,7 @@ type schedt struct {
 
        pidle      puintptr // idle p's
        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.
        runq     gQueue