// the case where *all* scannable memory turns out to be live, and
	// *all* allocated stack space is scannable.
	maxStackScan := c.maxStackScan.Load()
	maxScanWork := int64(scan + maxStackScan + c.globalsScan.Load())
	if work > scanWorkExpected {
		// We've already done more scan work than expected. Because our expectation
		// is based on a steady-state scannable heap size, we assume this means our

		Cumulative:  true,
	},
	{
		Name:        "/gc/scan/globals:bytes",
		Description: "The total amount of global variable space that is scannable.",
		Kind:        KindUint64,
	},
	{
		Name:        "/gc/scan/heap:bytes",
		Description: "The total amount of heap space that is scannable.",
		Kind:        KindUint64,
	},
	{
		Name:        "/gc/scan/stack:bytes",

	/gc/scan/globals:bytes
		The total amount of global variable space that is scannable.

	/gc/scan/heap:bytes
		The total amount of heap space that is scannable.

	/gc/scan/stack:bytes
		The number of bytes of stack that were scanned last GC cycle.

	/gc/scan/total:bytes
		The total amount space that is scannable. Sum of all metrics in
		/gc/scan.

	/gc/stack/starting-size:bytes

		#->#-># MB   heap size at GC start, at GC end, and live heap, or /gc/scan/heap:bytes
		# MB goal    goal heap size, or /gc/heap/goal:bytes
		# MB stacks  estimated scannable stack size, or /gc/scan/stack:bytes
		# MB globals scannable global size, or /gc/scan/globals:bytes
		# P          number of processors used, or /sched/gomaxprocs:threads
	The phases are stop-the-world (STW) sweep termination, concurrent

	// The following members are accessed on every malloc,
	// so they are grouped here for better caching.
	nextSample uintptr // trigger heap sample after allocating this many bytes
	scanAlloc  uintptr // bytes of scannable heap allocated

	// Allocator cache for tiny objects w/o pointers.
	// See "Tiny allocator" comment in malloc.go.

	// tiny points to the beginning of the current tiny block, or
	// nil if there is no current tiny block.

		println("x")
	}
}

func TestGCTestIsReachable(t *testing.T) {
	var all, half []unsafe.Pointer
	var want uint64
	for i := 0; i < 16; i++ {
		// The tiny allocator muddies things, so we use a
		// scannable type.
		p := unsafe.Pointer(new(*int))
		all = append(all, p)
		if i%2 == 0 {
			half = append(half, p)
			want |= 1 << i
		}
	}

	got := runtime.GCTestIsReachable(all...)
	if got&want != want {

					assertInRange(t, "goal ratio", c[n-1].goalRatio(), 0.95, 1.05)
				}
			},
		},
		{
			// This tests the GC pacer's response to a change in the fraction of the scannable heap.
			name:          "StepScannableFrac",
			gcPercent:     100,
			memoryLimit:   math.MaxInt64,
			globalsBytes:  32 << 10,
			nCores:        8,
			allocRate:     constant(128.0),

	// under a scannable-threshold. As an optimization, we could permit the *int
	// to be nil when the set is small and should be scanned. This works even if
	// the set grows over the threshold with delete handles outstanding because
	// an element can only move to a lower index. So if it starts with a nil
	// position, it'll always be in a low index and thus scannable. But that
	// can be done in a follow-up change.

		throw("user arena chunk is not aligned to the physical page size")
	}

	return x, span
}

// isUnusedUserArenaChunk indicates that the arena chunk has been set to fault
// and doesn't contain any scannable memory anymore. However, it might still be
// mSpanInUse as it sits on the quarantine list, since it needs to be swept.
//
// This is not safe to execute unless the caller has ownership of the mspan or

	// Check to see if that value makes sense.
	if gc.pauses < gc.numGC*2 {
		t.Errorf("fewer pauses than expected: got %d, want at least %d", gc.pauses, gc.numGC*2)
	}
	if totalScan.got <= 0 {
		t.Errorf("scannable GC space is empty: %d", totalScan.got)
	}
	if totalScan.got != totalScan.want {
		t.Errorf("/gc/scan/total:bytes doesn't line up with sum of /gc/scan*: total %d vs. sum %d", totalScan.got, totalScan.want)
	}
}