lastHeapGoal uint64

	// heapLive is the number of bytes considered live by the GC.
	// That is: retained by the most recent GC plus allocated
	// since then. heapLive ≤ memstats.totalAlloc-memstats.totalFree, since
	// heapAlloc includes unmarked objects that have not yet been swept (and
	// hence goes up as we allocate and down as we sweep) while heapLive
	// excludes these objects (and hence only goes up between GCs).

	// Store the current alloc count for accounting later.
	s.allocCountBeforeCache = s.allocCount

	// Update heapLive and flush scanAlloc.
	//
	// We have not yet allocated anything new into the span, but we
	// assume that all of its slots will get used, so this makes
	// heapLive an overestimate.
	//
	// When the span gets uncached, we'll fix up this overestimate
	// if necessary (see releaseAll).
	//

	return float64(r.heapGoal - r.heapTrigger)
}

func (r *gcCycleResult) triggerRatio() float64 {
	return float64(r.heapTrigger-r.heapLive) / float64(r.heapGoal-r.heapLive)
}

func (r *gcCycleResult) String() string {
	return fmt.Sprintf("%d %2.1f%% %d->%d->%d (goal: %d)", r.cycle, r.gcUtilization*100, r.heapLive, r.heapTrigger, r.heapPeak, r.heapGoal)
}

func assertInEpsilon(t *testing.T, name string, a, b, epsilon float64) {

	EvGoInSyscall       = 32 // denotes that goroutine is in syscall when tracing starts [timestamp, goroutine id]
	EvHeapAlloc         = 33 // gcController.heapLive change [timestamp, heap live bytes]
	EvHeapGoal          = 34 // gcController.heapGoal change [timestamp, heap goal bytes]
	EvTimerGoroutine    = 35 // denotes timer goroutine [timer goroutine id]

	return c.heapGoal()
}

func (c *GCController) HeapLive() uint64 {
	return c.heapLive.Load()
}

func (c *GCController) HeapMarked() uint64 {
	return c.heapMarked
}

func (c *GCController) Triggered() uint64 {
	return c.triggered
}

type GCControllerReviseDelta struct {
	HeapLive        int64
	HeapScan        int64
	HeapScanWork    int64

			throw("mismatched begin/end of activeSweep")
		}
		if a.state.CompareAndSwap(state, state-1) {
			if state != sweepDrainedMask {
				return
			}
			if debug.gcpacertrace > 0 {
				live := gcController.heapLive.Load()
				print("pacer: sweep done at heap size ", live>>20, "MB; allocated ", (live-mheap_.sweepHeapLiveBasis)>>20, "MB during sweep; swept ", mheap_.pagesSwept.Load(), " pages at ", mheap_.sweepPagesPerByte, " pages/byte\n")
			}

	mode gcMode

	// userForced indicates the current GC cycle was forced by an
	// explicit user call.
	userForced bool

	// initialHeapLive is the value of gcController.heapLive at the
	// beginning of this GC cycle.
	initialHeapLive uint64

	// assistQueue is a queue of assists that are blocked because
	// there was neither enough credit to steal or enough work to
	// do.

	traceEvGCMarkAssistBegin  // GC mark assist start [timestamp, stack ID]
	traceEvGCMarkAssistEnd    // GC mark assist done [timestamp]
	traceEvHeapAlloc          // gcController.heapLive change [timestamp, heap alloc in bytes]
	traceEvHeapGoal           // gcController.heapGoal() change [timestamp, heap goal in bytes]

	// Annotations.

		throw("newUserArenaChunk called with gcphase == _GCmarktermination")
	}

	// Deduct assist credit. Because user arena chunks are modeled as one
	// giant heap object which counts toward heapLive, we're obligated to
	// assist the GC proportionally (and it's worth noting that the arena
	// does represent additional work for the GC, but we also have no idea

	EvGCMarkAssistBegin  // GC mark assist start [timestamp, stack ID]
	EvGCMarkAssistEnd    // GC mark assist done [timestamp]
	EvHeapAlloc          // gcController.heapLive change [timestamp, heap alloc in bytes]
	EvHeapGoal           // gcController.heapGoal() change [timestamp, heap goal in bytes]

	// Annotations.