var value time.Duration
				for _, sample := range p.Sample {
					value += time.Duration(sample.Value[1]) * time.Nanosecond
				}

				totalTime := userTime + systemTime
				t.Logf("compare %s user + %s system = %s vs %s", userTime, systemTime, totalTime, value)
				if err := compare(totalTime, value, maxDiff); err != nil {
					t.Logf("compare got %v want nil", err)
					ok = false
				}

				return ok
			}

	// Compute overall GC CPU utilization.
	// Omit idle marking time from the overall utilization here since it's "free".
	memstats.gc_cpu_fraction = float64(work.cpuStats.GCTotalTime-work.cpuStats.GCIdleTime) / float64(work.cpuStats.TotalTime)

	// Reset assist time and background time stats.
	//
	// Do this now, instead of at the start of the next GC cycle, because
	// these two may keep accumulating even if the GC is not active.