work.cpuStats.accumulateGCPauseTime(nanotime()-stw.finishedStopping, work.maxprocs)

	// Concurrent mark.
	systemstack(func() {
		now = startTheWorldWithSema(0, stw)
		work.pauseNS += now - stw.startedStopping
		work.tMark = now

		// Release the CPU limiter.
		gcCPULimiter.finishGCTransition(now)
	})

	// Release the world sema before Gosched() in STW mode

	buf := gp.writebuf
	gp.writebuf = nil

	return string(buf)
}

func ResetDebugLog() {
	stw := stopTheWorld(stwForTestResetDebugLog)
	for l := allDloggers; l != nil; l = l.allLink {
		l.w.write = 0
		l.w.tick, l.w.nano = 0, 0
		l.w.r.begin, l.w.r.end = 0, 0
		l.w.r.tick, l.w.r.nano = 0, 0
	}
	startTheWorld(stw)

        </p>
        <p>
          <b>Include</b><br>
          <input type="checkbox" id="stw" checked><label for="stw">STW</label>
          <span class="help">?<span>Stop-the-world stops all goroutines simultaneously.</span></span><br>
          <input type="checkbox" id="background" checked><label for="background">Background workers</label>

	}

	lock(&sched.lock)
	ret := int(gomaxprocs)
	unlock(&sched.lock)
	if n <= 0 || n == ret {
		return ret
	}

	stw := stopTheWorldGC(stwGOMAXPROCS)

	// newprocs will be processed by startTheWorld
	newprocs = int32(n)

	startTheWorldGC(stw)
	return ret
}

// NumCPU returns the number of logical CPUs usable by the current process.
//

	var total uint64
	for _, ns := range pauses {
		total += ns
	}
	// ns/op for this benchmark is average STW time.
	b.ReportMetric(float64(total)/float64(b.N), "ns/op")
	b.ReportMetric(float64(pauses[len(pauses)*95/100]), "p95-ns/STW")
	b.ReportMetric(float64(pauses[len(pauses)*50/100]), "p50-ns/STW")
}

func BenchmarkPoolExpensiveNew(b *testing.B) {
	// Populate a pool with items that are expensive to construct

	traceEvGoStatus            // goroutine status at the start of a generation [timestamp, goroutine ID, M ID, status]

	// STW.
	traceEvSTWBegin // STW start [timestamp, kind]
	traceEvSTWEnd   // STW done [timestamp]

	// GC events.
	traceEvGCActive           // GC active [timestamp, seq]
	traceEvGCBegin            // GC start [timestamp, seq, stack ID]

	// is in the range [0, 1].
	Util float64
}

// UtilFlags controls the behavior of MutatorUtilization.
type UtilFlags int

const (
	// UtilSTW means utilization should account for STW events.
	// This includes non-GC STW events, which are typically user-requested.
	UtilSTW UtilFlags = 1 << iota
	// UtilBackground means utilization should account for
	// background mark workers.
	UtilBackground

	EvGoStatus            // goroutine status at the start of a generation [timestamp, goroutine ID, thread ID, status]

	// STW.
	EvSTWBegin // STW start [timestamp, kind]
	EvSTWEnd   // STW done [timestamp]

	// GC events.
	EvGCActive           // GC active [timestamp, seq]
	EvGCBegin            // GC start [timestamp, seq, stack ID]

}

// finishGCTransition notifies the limiter that the GC transition is complete
// and releases ownership of it. It also accumulates STW time in the bucket.
// now must be the timestamp from the end of the STW pause.
func (l *gcCPULimiterState) finishGCTransition(now int64) {
	if !l.transitioning {
		throw("finishGCTransition called without starting one?")
	}

		// allocation estimate without bothering to STW. As long as
		// this is close, then we'll only need to STW once (on the next
		// call).
		return int(gcount()), false
	}

	semacquire(&goroutineProfile.sema)

	ourg := getg()

	pcbuf := makeProfStack() // see saveg() for explanation
	stw := stopTheWorld(stwGoroutineProfile)