// the heap.
	h.spanalloc.free(unsafe.Pointer(s))
}

// allocSpan allocates an mspan which owns npages worth of memory.
//
// If typ.manual() == false, allocSpan allocates a heap span of class spanclass
// and updates heap accounting. If manual == true, allocSpan allocates a
// manually-managed span (spanclass is ignored), and the caller is

	limiterEventMarkAssist                             // Refers to mark assist (see gcAssistAlloc).
	limiterEventScavengeAssist                         // Refers to a scavenge assist (see allocSpan).
	limiterEventIdle                                   // Refers to time a P spent on the idle list.

	limiterEventBits = 3
)

// limiterEventTypeMask is a mask for the bits in p.limiterEventStart that represent

		runtime.GC()
		runtime.GC()
		b.StopTimer()
	}
	close(teardown)
}

func BenchmarkMSpanCountAlloc(b *testing.B) {
	// Allocate one dummy mspan for the whole benchmark.
	s := runtime.AllocMSpan()
	defer runtime.FreeMSpan(s)

	// n is the number of bytes to benchmark against.
	// n must always be a multiple of 8, since gcBits is
	// always rounded up 8 bytes.
	for _, n := range []int{8, 16, 32, 64, 128} {

	if s != nil {
		releaseSudog(s)
		return true
	}
	return false
}

// mspan wrapper for testing.
type MSpan mspan

// Allocate an mspan for testing.
func AllocMSpan() *MSpan {
	var s *mspan
	systemstack(func() {
		lock(&mheap_.lock)
		s = (*mspan)(mheap_.spanalloc.alloc())
		unlock(&mheap_.lock)
	})
	return (*MSpan)(s)
}