// Initialize a new byte slice with pseduo-random data.
			bits := make([]byte, n)
			rand.Read(bits)

			b.ResetTimer()
			for i := 0; i < b.N; i++ {
				runtime.MSpanCountAlloc(s, bits)
			}
		})
	}
}

func countpwg(n *int, ready *sync.WaitGroup, teardown chan bool) {
	if *n == 0 {
		ready.Done()
		<-teardown
		return
	}
	*n--

// Free an allocated mspan.
func FreeMSpan(s *MSpan) {
	systemstack(func() {
		lock(&mheap_.lock)
		mheap_.spanalloc.free(unsafe.Pointer(s))
		unlock(&mheap_.lock)
	})
}

func MSpanCountAlloc(ms *MSpan, bits []byte) int {
	s := (*mspan)(ms)
	s.nelems = uint16(len(bits) * 8)
	s.gcmarkBits = (*gcBits)(unsafe.Pointer(&bits[0]))
	result := s.countAlloc()
	s.gcmarkBits = nil
	return result
}