window time.Duration
		want   float64
		worst  []float64
	}{
		{0, 0, []float64{}},
		{time.Millisecond, 0, []float64{0, 0}},
		{time.Second, 0, []float64{0, 0}},
		{2 * time.Second, 0.5, []float64{0.5, 0.5}},
		{3 * time.Second, 1 / 3.0, []float64{1 / 3.0}},
		{4 * time.Second, 0.5, []float64{0.5}},
		{5 * time.Second, 3 / 5.0, []float64{3 / 5.0}},
		{6 * time.Second, 3 / 5.0, []float64{3 / 5.0}},
	} {

		{"ns", []string{"ns", "nanosecond"}, float64(time.Nanosecond)},
		{"us", []string{"μs", "us", "microsecond"}, float64(time.Microsecond)},
		{"ms", []string{"ms", "millisecond"}, float64(time.Millisecond)},
		{"s", []string{"s", "sec", "second"}, float64(time.Second)},
		{"hrs", []string{"hour", "hr"}, float64(time.Hour)},
	},
	DefaultUnit: Unit{"s", []string{}, float64(time.Second)},
}, {
	Units: []Unit{

					m.Set(bucketReplProxiedHeadRequestsTotal, float64(s.ProxyStats.HeadTotal), labels...)
					m.Set(bucketReplProxiedPutTaggingRequestsFailures, float64(s.ProxyStats.PutTagFailedTotal), labels...)
					m.Set(bucketReplProxiedPutTaggingRequestsTotal, float64(s.ProxyStats.PutTagTotal), labels...)
					m.Set(bucketReplSentCount, float64(stat.ReplicatedCount), labels...)

	// label to "s3".

	m.Set(apiRejectedAuthTotal, float64(httpStats.TotalS3RejectedAuth), "type", "s3")
	m.Set(apiRejectedTimestampTotal, float64(httpStats.TotalS3RejectedTime), "type", "s3")
	m.Set(apiRejectedHeaderTotal, float64(httpStats.TotalS3RejectedHeader), "type", "s3")
	m.Set(apiRejectedInvalidTotal, float64(httpStats.TotalS3RejectedInvalid), "type", "s3")
	m.Set(apiRequestsWaitingTotal, float64(httpStats.S3RequestsInQueue), "type", "s3")

//
// The true inverse cumulative sum will be in the range [lower, upper).
func (d *mud) approxInvCumulativeSum() (float64, float64, bool) {
	if d.trackBucket == len(d.hist) {
		return math.NaN(), math.NaN(), false
	}
	return float64(d.trackBucket) / mudDegree, float64(d.trackBucket+1) / mudDegree, true
}

// invCumulativeSum returns x such that the integral of d from -∞ to x

	qt := qs.QStats
	m.Set(replicationAverageQueuedBytes, float64(qt.Avg.Bytes))
	m.Set(replicationAverageQueuedCount, float64(qt.Avg.Count))
	m.Set(replicationMaxQueuedBytes, float64(qt.Max.Bytes))
	m.Set(replicationMaxQueuedCount, float64(qt.Max.Count))
	m.Set(replicationLastMinuteQueuedBytes, float64(qt.Curr.Bytes))
	m.Set(replicationLastMinuteQueuedCount, float64(qt.Curr.Count))

	qa := qs.ActiveWorkers

			}
			addGauge(volumeStatsCapacityBytesDesc, pvcRef, float64(*volumeStat.CapacityBytes))
			addGauge(volumeStatsAvailableBytesDesc, pvcRef, float64(*volumeStat.AvailableBytes))
			addGauge(volumeStatsUsedBytesDesc, pvcRef, float64(*volumeStat.UsedBytes))
			addGauge(volumeStatsInodesDesc, pvcRef, float64(*volumeStat.Inodes))
			addGauge(volumeStatsInodesFreeDesc, pvcRef, float64(*volumeStat.InodesFree))

	m.Set(driveUsedBytes, float64(drive.UsedSpace), labels...)
	m.Set(driveFreeBytes, float64(drive.AvailableSpace), labels...)
	m.Set(driveTotalBytes, float64(drive.TotalSpace), labels...)
	m.Set(driveUsedInodes, float64(drive.UsedInodes), labels...)
	m.Set(driveFreeInodes, float64(drive.FreeInodes), labels...)
	m.Set(driveTotalInodes, float64(drive.UsedInodes+drive.FreeInodes), labels...)

	m.Set(scannerBucketScansFinished, float64(globalScannerMetrics.lifetime(scannerMetricScanBucketDrive)))
	m.Set(scannerBucketScansStarted, float64(globalScannerMetrics.lifetime(scannerMetricScanBucketDrive)+uint64(globalScannerMetrics.activeDrives())))
	m.Set(scannerDirectoriesScanned, float64(globalScannerMetrics.lifetime(scannerMetricScanFolder)))
	m.Set(scannerObjectsScanned, float64(globalScannerMetrics.lifetime(scannerMetricScanObject)))

	// Insert random uniforms and check histogram mass and
	// cumulative sum approximations.
	rnd := rand.New(rand.NewSource(42))
	mass := 0.0
	var mud mud
	for i := 0; i < 100; i++ {
		area, l, r := rnd.Float64(), rnd.Float64(), rnd.Float64()
		if rnd.Intn(10) == 0 {
			r = l
		}
		t.Log(l, r, area)
		mud.add(l, r, area)
		mass += area

		// Check total histogram weight.
		hmass := 0.0
		for _, val := range mud.hist {