for i := 0; i < b.N; i++ {
		b.StartTimer()
		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.

		case "/memory/classes/metadata/mcache/inuse:bytes":
			checkUint64(t, name, samples[i].Value.Uint64(), mstats.MCacheInuse)
		case "/memory/classes/metadata/mspan/free:bytes":
			checkUint64(t, name, samples[i].Value.Uint64(), mstats.MSpanSys-mstats.MSpanInuse)
		case "/memory/classes/metadata/mspan/inuse:bytes":
			checkUint64(t, name, samples[i].Value.Uint64(), mstats.MSpanInuse)
		case "/memory/classes/metadata/other:bytes":

	sudogbuf   [128]*sudog

	// Cache of mspan objects from the heap.
	mspancache struct {
		// We need an explicit length here because this field is used
		// in allocation codepaths where write barriers are not allowed,
		// and eliminating the write barrier/keeping it eliminated from
		// slice updates is tricky, more so than just managing the length
		// ourselves.
		len int
		buf [128]*mspan
	}

	fmt.Fprintf(w, "# HeapReleased = %d\n", s.HeapReleased)
	fmt.Fprintf(w, "# HeapObjects = %d\n", s.HeapObjects)

	fmt.Fprintf(w, "# Stack = %d / %d\n", s.StackInuse, s.StackSys)
	fmt.Fprintf(w, "# MSpan = %d / %d\n", s.MSpanInuse, s.MSpanSys)
	fmt.Fprintf(w, "# MCache = %d / %d\n", s.MCacheInuse, s.MCacheSys)
	fmt.Fprintf(w, "# BuckHashSys = %d\n", s.BuckHashSys)
	fmt.Fprintf(w, "# GCSys = %d\n", s.GCSys)

// starting with 1 above. See discussion of GC rate below.

// Concurrent sweep.
//
// The sweep phase proceeds concurrently with normal program execution.
// The heap is swept span-by-span both lazily (when a goroutine needs another span)
// and concurrently in a background goroutine (this helps programs that are not CPU bound).
// At the end of STW mark termination all spans are marked as "needs sweeping".
//

 │                          │
 │  <span style="background-color:#272822"><font color="#FF4689">from</font></span><span style="background-color:#272822"><font color="#F8F8F2"> main </font></span><span style="background-color:#272822"><font color="#FF4689">import</font></span><span style="background-color:#272822"><font color="#F8F8F2"> app</font></span><span style="background-color:#272822">  </span>  │
 │                          │

          {{/* source line */ -}}
          <span class=line>{{printf " %6d" .Line}}</span>{{" " -}}
          <span class={{.HTMLClass}}>
            {{- printf "  %10s %10s %8s  %s " .Flat .Cumulative "" .SrcLine -}}
          </span>{{"" -}}

          {{if .Instructions -}}
            {{/* instructions for this source line */ -}}
            <span class=asm>{{"" -}}
            {{range .Instructions -}}

 │                          │
 │  <span style="background-color:#272822"><font color="#FF4689">from</font></span><span style="background-color:#272822"><font color="#F8F8F2"> main </font></span><span style="background-color:#272822"><font color="#FF4689">import</font></span><span style="background-color:#272822"><font color="#F8F8F2"> app</font></span><span style="background-color:#272822">  </span>  │
 │                          │

 │                          │
 │  <span style="background-color:#272822"><font color="#FF4689">from</font></span><span style="background-color:#272822"><font color="#F8F8F2"> main </font></span><span style="background-color:#272822"><font color="#FF4689">import</font></span><span style="background-color:#272822"><font color="#F8F8F2"> app</font></span><span style="background-color:#272822">  </span>  │
 │                          │

 │                          │
 │  <span style="background-color:#272822"><font color="#FF4689">from</font></span><span style="background-color:#272822"><font color="#F8F8F2"> main </font></span><span style="background-color:#272822"><font color="#FF4689">import</font></span><span style="background-color:#272822"><font color="#F8F8F2"> app</font></span><span style="background-color:#272822">  </span>  │
 │                          │