publish storage API latency through node metrics (#14117)

Publish storage functions latency to help compare the performance 
of different disks in a single deployment.

e.g.:
```
minio_node_disk_latency_us{api="storage.WalkDir",disk="/tmp/xl/1",server="localhost:9001"} 226
minio_node_disk_latency_us{api="storage.WalkDir",disk="/tmp/xl/2",server="localhost:9002"} 1180
minio_node_disk_latency_us{api="storage.WalkDir",disk="/tmp/xl/3",server="localhost:9003"} 1183
minio_node_disk_latency_us{api="storage.WalkDir",disk="/tmp/xl/4",server="localhost:9004"} 1625
```

cmd/bucket-stats.go

@@ -38,7 +38,7 @@ func (rl ReplicationLatency) merge(other ReplicationLatency) (newReplLatency Rep
 // Get upload latency of each object size range
 func (rl ReplicationLatency) getUploadLatency() (ret map[string]uint64) {
 	ret = make(map[string]uint64)
-	avg := rl.UploadHistogram.GetAvg()
+	avg := rl.UploadHistogram.GetAvgData()
 	for k, v := range avg {
 		// Convert nanoseconds to milliseconds
 		ret[sizeTagToString(k)] = v.avg() / uint64(time.Millisecond)

cmd/last-minute.go

@@ -15,6 +15,8 @@
 // You should have received a copy of the GNU Affero General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+//go:generate msgp -file=$GOFILE -unexported
+
 package cmd
 
 import (
@@ -76,34 +78,34 @@ type AccElem struct {
 	N     int64
 }
 
-// add dur to a as a single element.
+// Add a duration to a single element.
 func (a *AccElem) add(dur time.Duration) {
 	a.Total += int64(dur)
 	a.N++
 }
 
-// merge b into a.
+// Merge b into a.
 func (a *AccElem) merge(b AccElem) {
 	a.N += b.N
 	a.Total += b.Total
 }
 
-// avg converts total to average.
-func (a *AccElem) avg() uint64 {
+// Avg converts total to average.
+func (a AccElem) avg() uint64 {
 	if a.N >= 1 && a.Total > 0 {
 		return uint64(a.Total / a.N)
 	}
 	return 0
 }
 
-// LastMinuteLatencies keeps track of last minute latencies.
-type LastMinuteLatencies struct {
-	Totals  [60][sizeLastElemMarker]AccElem
+// lastMinuteLatency keeps track of last minute latency.
+type lastMinuteLatency struct {
+	Totals  [60]AccElem
 	LastSec int64
 }
 
-// Merge safely merges two LastMinuteLatencies structures into one
-func (l LastMinuteLatencies) Merge(o LastMinuteLatencies) (merged LastMinuteLatencies) {
+// Merge data of two lastMinuteLatency structure
+func (l lastMinuteLatency) merge(o lastMinuteLatency) (merged lastMinuteLatency) {
 	if l.LastSec > o.LastSec {
 		o.forwardTo(l.LastSec)
 		merged.LastSec = l.LastSec
@@ -113,57 +115,73 @@ func (l LastMinuteLatencies) Merge(o LastMinuteLatencies) (merged LastMinuteLate
 	}
 
 	for i := range merged.Totals {
-		for j := range merged.Totals[i] {
-			merged.Totals[i][j] = AccElem{
-				Total: l.Totals[i][j].Total + o.Totals[i][j].Total,
-				N:     l.Totals[i][j].N + o.Totals[i][j].N,
-			}
+		merged.Totals[i] = AccElem{
+			Total: l.Totals[i].Total + o.Totals[i].Total,
+			N:     l.Totals[i].N + o.Totals[i].N,
 		}
 	}
 	return merged
 }
 
+// Add  a new duration data
+func (l *lastMinuteLatency) add(t time.Duration) {
+	sec := time.Now().Unix()
+	l.forwardTo(sec)
+	winIdx := sec % 60
+	l.Totals[winIdx].add(t)
+	l.LastSec = sec
+}
+
+// Merge all recorded latencies of last minute into one
+func (l *lastMinuteLatency) getAvgData() AccElem {
+	var res AccElem
+	sec := time.Now().Unix()
+	l.forwardTo(sec)
+	for _, elem := range l.Totals[:] {
+		res.merge(elem)
+	}
+	return res
+}
+
+// forwardTo time t, clearing any entries in between.
+func (l *lastMinuteLatency) forwardTo(t int64) {
+	if l.LastSec >= t {
+		return
+	}
+	if t-l.LastSec >= 60 {
+		l.Totals = [60]AccElem{}
+		return
+	}
+	for l.LastSec != t {
+		// Clear next element.
+		idx := (l.LastSec + 1) % 60
+		l.Totals[idx] = AccElem{}
+		l.LastSec++
+	}
+}
+
+// LastMinuteLatencies keeps track of last minute latencies.
+type LastMinuteLatencies [sizeLastElemMarker]lastMinuteLatency
+
+// Merge safely merges two LastMinuteLatencies structures into one
+func (l LastMinuteLatencies) Merge(o LastMinuteLatencies) (merged LastMinuteLatencies) {
+	for i := range l {
+		merged[i] = l[i].merge(o[i])
+	}
+	return merged
+}
+
 // Add latency t from object with the specified size.
 func (l *LastMinuteLatencies) Add(size int64, t time.Duration) {
-	tag := sizeToTag(size)
-
-	// Update...
-	sec := time.Now().Unix()
-	l.forwardTo(sec)
-
-	winIdx := sec % 60
-	l.Totals[winIdx][tag].add(t)
-
-	l.LastSec = sec
+	l[sizeToTag(size)].add(t)
 }
 
-// GetAvg will return the average for each bucket from the last time minute.
+// GetAvgData will return the average for each bucket from the last time minute.
 // The number of objects is also included.
-func (l *LastMinuteLatencies) GetAvg() [sizeLastElemMarker]AccElem {
+func (l *LastMinuteLatencies) GetAvgData() [sizeLastElemMarker]AccElem {
 	var res [sizeLastElemMarker]AccElem
-	sec := time.Now().Unix()
-	l.forwardTo(sec)
-	for _, elems := range l.Totals[:] {
-		for j := range elems {
-			res[j].merge(elems[j])
-		}
+	for i, elem := range l[:] {
+		res[i] = elem.getAvgData()
 	}
 	return res
 }
-
-// forwardTo time t, clearing any entries in between.
-func (l *LastMinuteLatencies) forwardTo(t int64) {
-	if l.LastSec >= t {
-		return
-	}
-	if t-l.LastSec >= 60 {
-		l.Totals = [60][sizeLastElemMarker]AccElem{}
-		return
-	}
-	for l.LastSec != t {
-		// Clear next element.
-		idx := (l.LastSec + 1) % 60
-		l.Totals[idx] = [sizeLastElemMarker]AccElem{}
-		l.LastSec++
-	}
-}

cmd/last-minute_gen.go

@@ -136,6 +136,282 @@ func (z AccElem) Msgsize() (s int) {
 
 // DecodeMsg implements msgp.Decodable
 func (z *LastMinuteLatencies) DecodeMsg(dc *msgp.Reader) (err error) {
+	var zb0001 uint32
+	zb0001, err = dc.ReadArrayHeader()
+	if err != nil {
+		err = msgp.WrapError(err)
+		return
+	}
+	if zb0001 != uint32(sizeLastElemMarker) {
+		err = msgp.ArrayError{Wanted: uint32(sizeLastElemMarker), Got: zb0001}
+		return
+	}
+	for za0001 := range z {
+		var field []byte
+		_ = field
+		var zb0002 uint32
+		zb0002, err = dc.ReadMapHeader()
+		if err != nil {
+			err = msgp.WrapError(err, za0001)
+			return
+		}
+		for zb0002 > 0 {
+			zb0002--
+			field, err = dc.ReadMapKeyPtr()
+			if err != nil {
+				err = msgp.WrapError(err, za0001)
+				return
+			}
+			switch msgp.UnsafeString(field) {
+			case "Totals":
+				var zb0003 uint32
+				zb0003, err = dc.ReadArrayHeader()
+				if err != nil {
+					err = msgp.WrapError(err, za0001, "Totals")
+					return
+				}
+				if zb0003 != uint32(60) {
+					err = msgp.ArrayError{Wanted: uint32(60), Got: zb0003}
+					return
+				}
+				for za0002 := range z[za0001].Totals {
+					var zb0004 uint32
+					zb0004, err = dc.ReadMapHeader()
+					if err != nil {
+						err = msgp.WrapError(err, za0001, "Totals", za0002)
+						return
+					}
+					for zb0004 > 0 {
+						zb0004--
+						field, err = dc.ReadMapKeyPtr()
+						if err != nil {
+							err = msgp.WrapError(err, za0001, "Totals", za0002)
+							return
+						}
+						switch msgp.UnsafeString(field) {
+						case "Total":
+							z[za0001].Totals[za0002].Total, err = dc.ReadInt64()
+							if err != nil {
+								err = msgp.WrapError(err, za0001, "Totals", za0002, "Total")
+								return
+							}
+						case "N":
+							z[za0001].Totals[za0002].N, err = dc.ReadInt64()
+							if err != nil {
+								err = msgp.WrapError(err, za0001, "Totals", za0002, "N")
+								return
+							}
+						default:
+							err = dc.Skip()
+							if err != nil {
+								err = msgp.WrapError(err, za0001, "Totals", za0002)
+								return
+							}
+						}
+					}
+				}
+			case "LastSec":
+				z[za0001].LastSec, err = dc.ReadInt64()
+				if err != nil {
+					err = msgp.WrapError(err, za0001, "LastSec")
+					return
+				}
+			default:
+				err = dc.Skip()
+				if err != nil {
+					err = msgp.WrapError(err, za0001)
+					return
+				}
+			}
+		}
+	}
+	return
+}
+
+// EncodeMsg implements msgp.Encodable
+func (z *LastMinuteLatencies) EncodeMsg(en *msgp.Writer) (err error) {
+	err = en.WriteArrayHeader(uint32(sizeLastElemMarker))
+	if err != nil {
+		err = msgp.WrapError(err)
+		return
+	}
+	for za0001 := range z {
+		// map header, size 2
+		// write "Totals"
+		err = en.Append(0x82, 0xa6, 0x54, 0x6f, 0x74, 0x61, 0x6c, 0x73)
+		if err != nil {
+			return
+		}
+		err = en.WriteArrayHeader(uint32(60))
+		if err != nil {
+			err = msgp.WrapError(err, za0001, "Totals")
+			return
+		}
+		for za0002 := range z[za0001].Totals {
+			// map header, size 2
+			// write "Total"
+			err = en.Append(0x82, 0xa5, 0x54, 0x6f, 0x74, 0x61, 0x6c)
+			if err != nil {
+				return
+			}
+			err = en.WriteInt64(z[za0001].Totals[za0002].Total)
+			if err != nil {
+				err = msgp.WrapError(err, za0001, "Totals", za0002, "Total")
+				return
+			}
+			// write "N"
+			err = en.Append(0xa1, 0x4e)
+			if err != nil {
+				return
+			}
+			err = en.WriteInt64(z[za0001].Totals[za0002].N)
+			if err != nil {
+				err = msgp.WrapError(err, za0001, "Totals", za0002, "N")
+				return
+			}
+		}
+		// write "LastSec"
+		err = en.Append(0xa7, 0x4c, 0x61, 0x73, 0x74, 0x53, 0x65, 0x63)
+		if err != nil {
+			return
+		}
+		err = en.WriteInt64(z[za0001].LastSec)
+		if err != nil {
+			err = msgp.WrapError(err, za0001, "LastSec")
+			return
+		}
+	}
+	return
+}
+
+// MarshalMsg implements msgp.Marshaler
+func (z *LastMinuteLatencies) MarshalMsg(b []byte) (o []byte, err error) {
+	o = msgp.Require(b, z.Msgsize())
+	o = msgp.AppendArrayHeader(o, uint32(sizeLastElemMarker))
+	for za0001 := range z {
+		// map header, size 2
+		// string "Totals"
+		o = append(o, 0x82, 0xa6, 0x54, 0x6f, 0x74, 0x61, 0x6c, 0x73)
+		o = msgp.AppendArrayHeader(o, uint32(60))
+		for za0002 := range z[za0001].Totals {
+			// map header, size 2
+			// string "Total"
+			o = append(o, 0x82, 0xa5, 0x54, 0x6f, 0x74, 0x61, 0x6c)
+			o = msgp.AppendInt64(o, z[za0001].Totals[za0002].Total)
+			// string "N"
+			o = append(o, 0xa1, 0x4e)
+			o = msgp.AppendInt64(o, z[za0001].Totals[za0002].N)
+		}
+		// string "LastSec"
+		o = append(o, 0xa7, 0x4c, 0x61, 0x73, 0x74, 0x53, 0x65, 0x63)
+		o = msgp.AppendInt64(o, z[za0001].LastSec)
+	}
+	return
+}
+
+// UnmarshalMsg implements msgp.Unmarshaler
+func (z *LastMinuteLatencies) UnmarshalMsg(bts []byte) (o []byte, err error) {
+	var zb0001 uint32
+	zb0001, bts, err = msgp.ReadArrayHeaderBytes(bts)
+	if err != nil {
+		err = msgp.WrapError(err)
+		return
+	}
+	if zb0001 != uint32(sizeLastElemMarker) {
+		err = msgp.ArrayError{Wanted: uint32(sizeLastElemMarker), Got: zb0001}
+		return
+	}
+	for za0001 := range z {
+		var field []byte
+		_ = field
+		var zb0002 uint32
+		zb0002, bts, err = msgp.ReadMapHeaderBytes(bts)
+		if err != nil {
+			err = msgp.WrapError(err, za0001)
+			return
+		}
+		for zb0002 > 0 {
+			zb0002--
+			field, bts, err = msgp.ReadMapKeyZC(bts)
+			if err != nil {
+				err = msgp.WrapError(err, za0001)
+				return
+			}
+			switch msgp.UnsafeString(field) {
+			case "Totals":
+				var zb0003 uint32
+				zb0003, bts, err = msgp.ReadArrayHeaderBytes(bts)
+				if err != nil {
+					err = msgp.WrapError(err, za0001, "Totals")
+					return
+				}
+				if zb0003 != uint32(60) {
+					err = msgp.ArrayError{Wanted: uint32(60), Got: zb0003}
+					return
+				}
+				for za0002 := range z[za0001].Totals {
+					var zb0004 uint32
+					zb0004, bts, err = msgp.ReadMapHeaderBytes(bts)
+					if err != nil {
+						err = msgp.WrapError(err, za0001, "Totals", za0002)
+						return
+					}
+					for zb0004 > 0 {
+						zb0004--
+						field, bts, err = msgp.ReadMapKeyZC(bts)
+						if err != nil {
+							err = msgp.WrapError(err, za0001, "Totals", za0002)
+							return
+						}
+						switch msgp.UnsafeString(field) {
+						case "Total":
+							z[za0001].Totals[za0002].Total, bts, err = msgp.ReadInt64Bytes(bts)
+							if err != nil {
+								err = msgp.WrapError(err, za0001, "Totals", za0002, "Total")
+								return
+							}
+						case "N":
+							z[za0001].Totals[za0002].N, bts, err = msgp.ReadInt64Bytes(bts)
+							if err != nil {
+								err = msgp.WrapError(err, za0001, "Totals", za0002, "N")
+								return
+							}
+						default:
+							bts, err = msgp.Skip(bts)
+							if err != nil {
+								err = msgp.WrapError(err, za0001, "Totals", za0002)
+								return
+							}
+						}
+					}
+				}
+			case "LastSec":
+				z[za0001].LastSec, bts, err = msgp.ReadInt64Bytes(bts)
+				if err != nil {
+					err = msgp.WrapError(err, za0001, "LastSec")
+					return
+				}
+			default:
+				bts, err = msgp.Skip(bts)
+				if err != nil {
+					err = msgp.WrapError(err, za0001)
+					return
+				}
+			}
+		}
+	}
+	o = bts
+	return
+}
+
+// Msgsize returns an upper bound estimate of the number of bytes occupied by the serialized message
+func (z *LastMinuteLatencies) Msgsize() (s int) {
+	s = msgp.ArrayHeaderSize + (sizeLastElemMarker * (16 + (60 * (9 + msgp.Int64Size + msgp.Int64Size)) + msgp.Int64Size))
+	return
+}
+
+// DecodeMsg implements msgp.Decodable
+func (z *lastMinuteLatency) DecodeMsg(dc *msgp.Reader) (err error) {
 	var field []byte
 	_ = field
 	var zb0001 uint32
@@ -165,48 +441,36 @@ func (z *LastMinuteLatencies) DecodeMsg(dc *msgp.Reader) (err error) {
 			}
 			for za0001 := range z.Totals {
 				var zb0003 uint32
-				zb0003, err = dc.ReadArrayHeader()
+				zb0003, err = dc.ReadMapHeader()
 				if err != nil {
 					err = msgp.WrapError(err, "Totals", za0001)
 					return
 				}
-				if zb0003 != uint32(sizeLastElemMarker) {
-					err = msgp.ArrayError{Wanted: uint32(sizeLastElemMarker), Got: zb0003}
-					return
-				}
-				for za0002 := range z.Totals[za0001] {
-					var zb0004 uint32
-					zb0004, err = dc.ReadMapHeader()
+				for zb0003 > 0 {
+					zb0003--
+					field, err = dc.ReadMapKeyPtr()
 					if err != nil {
-						err = msgp.WrapError(err, "Totals", za0001, za0002)
+						err = msgp.WrapError(err, "Totals", za0001)
 						return
 					}
-					for zb0004 > 0 {
-						zb0004--
-						field, err = dc.ReadMapKeyPtr()
+					switch msgp.UnsafeString(field) {
+					case "Total":
+						z.Totals[za0001].Total, err = dc.ReadInt64()
 						if err != nil {
-							err = msgp.WrapError(err, "Totals", za0001, za0002)
+							err = msgp.WrapError(err, "Totals", za0001, "Total")
 							return
 						}
-						switch msgp.UnsafeString(field) {
-						case "Total":
-							z.Totals[za0001][za0002].Total, err = dc.ReadInt64()
-							if err != nil {
-								err = msgp.WrapError(err, "Totals", za0001, za0002, "Total")
-								return
-							}
-						case "N":
-							z.Totals[za0001][za0002].N, err = dc.ReadInt64()
-							if err != nil {
-								err = msgp.WrapError(err, "Totals", za0001, za0002, "N")
-								return
-							}
-						default:
-							err = dc.Skip()
-							if err != nil {
-								err = msgp.WrapError(err, "Totals", za0001, za0002)
-								return
-							}
+					case "N":
+						z.Totals[za0001].N, err = dc.ReadInt64()
+						if err != nil {
+							err = msgp.WrapError(err, "Totals", za0001, "N")
+							return
+						}
+					default:
+						err = dc.Skip()
+						if err != nil {
+							err = msgp.WrapError(err, "Totals", za0001)
+							return
 						}
 					}
 				}
@@ -229,7 +493,7 @@ func (z *LastMinuteLatencies) DecodeMsg(dc *msgp.Reader) (err error) {
 }
 
 // EncodeMsg implements msgp.Encodable
-func (z *LastMinuteLatencies) EncodeMsg(en *msgp.Writer) (err error) {
+func (z *lastMinuteLatency) EncodeMsg(en *msgp.Writer) (err error) {
 	// map header, size 2
 	// write "Totals"
 	err = en.Append(0x82, 0xa6, 0x54, 0x6f, 0x74, 0x61, 0x6c, 0x73)
@@ -242,33 +506,26 @@ func (z *LastMinuteLatencies) EncodeMsg(en *msgp.Writer) (err error) {
 		return
 	}
 	for za0001 := range z.Totals {
-		err = en.WriteArrayHeader(uint32(sizeLastElemMarker))
+		// map header, size 2
+		// write "Total"
+		err = en.Append(0x82, 0xa5, 0x54, 0x6f, 0x74, 0x61, 0x6c)
 		if err != nil {
-			err = msgp.WrapError(err, "Totals", za0001)
 			return
 		}
-		for za0002 := range z.Totals[za0001] {
-			// map header, size 2
-			// write "Total"
-			err = en.Append(0x82, 0xa5, 0x54, 0x6f, 0x74, 0x61, 0x6c)
-			if err != nil {
-				return
-			}
-			err = en.WriteInt64(z.Totals[za0001][za0002].Total)
-			if err != nil {
-				err = msgp.WrapError(err, "Totals", za0001, za0002, "Total")
-				return
-			}
-			// write "N"
-			err = en.Append(0xa1, 0x4e)
-			if err != nil {
-				return
-			}
-			err = en.WriteInt64(z.Totals[za0001][za0002].N)
-			if err != nil {
-				err = msgp.WrapError(err, "Totals", za0001, za0002, "N")
-				return
-			}
+		err = en.WriteInt64(z.Totals[za0001].Total)
+		if err != nil {
+			err = msgp.WrapError(err, "Totals", za0001, "Total")
+			return
+		}
+		// write "N"
+		err = en.Append(0xa1, 0x4e)
+		if err != nil {
+			return
+		}
+		err = en.WriteInt64(z.Totals[za0001].N)
+		if err != nil {
+			err = msgp.WrapError(err, "Totals", za0001, "N")
+			return
 		}
 	}
 	// write "LastSec"
@@ -285,23 +542,20 @@ func (z *LastMinuteLatencies) EncodeMsg(en *msgp.Writer) (err error) {
 }
 
 // MarshalMsg implements msgp.Marshaler
-func (z *LastMinuteLatencies) MarshalMsg(b []byte) (o []byte, err error) {
+func (z *lastMinuteLatency) MarshalMsg(b []byte) (o []byte, err error) {
 	o = msgp.Require(b, z.Msgsize())
 	// map header, size 2
 	// string "Totals"
 	o = append(o, 0x82, 0xa6, 0x54, 0x6f, 0x74, 0x61, 0x6c, 0x73)
 	o = msgp.AppendArrayHeader(o, uint32(60))
 	for za0001 := range z.Totals {
-		o = msgp.AppendArrayHeader(o, uint32(sizeLastElemMarker))
-		for za0002 := range z.Totals[za0001] {
-			// map header, size 2
-			// string "Total"
-			o = append(o, 0x82, 0xa5, 0x54, 0x6f, 0x74, 0x61, 0x6c)
-			o = msgp.AppendInt64(o, z.Totals[za0001][za0002].Total)
-			// string "N"
-			o = append(o, 0xa1, 0x4e)
-			o = msgp.AppendInt64(o, z.Totals[za0001][za0002].N)
-		}
+		// map header, size 2
+		// string "Total"
+		o = append(o, 0x82, 0xa5, 0x54, 0x6f, 0x74, 0x61, 0x6c)
+		o = msgp.AppendInt64(o, z.Totals[za0001].Total)
+		// string "N"
+		o = append(o, 0xa1, 0x4e)
+		o = msgp.AppendInt64(o, z.Totals[za0001].N)
 	}
 	// string "LastSec"
 	o = append(o, 0xa7, 0x4c, 0x61, 0x73, 0x74, 0x53, 0x65, 0x63)
@@ -310,7 +564,7 @@ func (z *LastMinuteLatencies) MarshalMsg(b []byte) (o []byte, err error) {
 }
 
 // UnmarshalMsg implements msgp.Unmarshaler
-func (z *LastMinuteLatencies) UnmarshalMsg(bts []byte) (o []byte, err error) {
+func (z *lastMinuteLatency) UnmarshalMsg(bts []byte) (o []byte, err error) {
 	var field []byte
 	_ = field
 	var zb0001 uint32
@@ -340,48 +594,36 @@ func (z *LastMinuteLatencies) UnmarshalMsg(bts []byte) (o []byte, err error) {
 			}
 			for za0001 := range z.Totals {
 				var zb0003 uint32
-				zb0003, bts, err = msgp.ReadArrayHeaderBytes(bts)
+				zb0003, bts, err = msgp.ReadMapHeaderBytes(bts)
 				if err != nil {
 					err = msgp.WrapError(err, "Totals", za0001)
 					return
 				}
-				if zb0003 != uint32(sizeLastElemMarker) {
-					err = msgp.ArrayError{Wanted: uint32(sizeLastElemMarker), Got: zb0003}
-					return
-				}
-				for za0002 := range z.Totals[za0001] {
-					var zb0004 uint32
-					zb0004, bts, err = msgp.ReadMapHeaderBytes(bts)
+				for zb0003 > 0 {
+					zb0003--
+					field, bts, err = msgp.ReadMapKeyZC(bts)
 					if err != nil {
-						err = msgp.WrapError(err, "Totals", za0001, za0002)
+						err = msgp.WrapError(err, "Totals", za0001)
 						return
 					}
-					for zb0004 > 0 {
-						zb0004--
-						field, bts, err = msgp.ReadMapKeyZC(bts)
+					switch msgp.UnsafeString(field) {
+					case "Total":
+						z.Totals[za0001].Total, bts, err = msgp.ReadInt64Bytes(bts)
 						if err != nil {
-							err = msgp.WrapError(err, "Totals", za0001, za0002)
+							err = msgp.WrapError(err, "Totals", za0001, "Total")
 							return
 						}
-						switch msgp.UnsafeString(field) {
-						case "Total":
-							z.Totals[za0001][za0002].Total, bts, err = msgp.ReadInt64Bytes(bts)
-							if err != nil {
-								err = msgp.WrapError(err, "Totals", za0001, za0002, "Total")
-								return
-							}
-						case "N":
-							z.Totals[za0001][za0002].N, bts, err = msgp.ReadInt64Bytes(bts)
-							if err != nil {
-								err = msgp.WrapError(err, "Totals", za0001, za0002, "N")
-								return
-							}
-						default:
-							bts, err = msgp.Skip(bts)
-							if err != nil {
-								err = msgp.WrapError(err, "Totals", za0001, za0002)
-								return
-							}
+					case "N":
+						z.Totals[za0001].N, bts, err = msgp.ReadInt64Bytes(bts)
+						if err != nil {
+							err = msgp.WrapError(err, "Totals", za0001, "N")
+							return
+						}
+					default:
+						bts, err = msgp.Skip(bts)
+						if err != nil {
+							err = msgp.WrapError(err, "Totals", za0001)
+							return
 						}
 					}
 				}
@@ -405,7 +647,7 @@ func (z *LastMinuteLatencies) UnmarshalMsg(bts []byte) (o []byte, err error) {
 }
 
 // Msgsize returns an upper bound estimate of the number of bytes occupied by the serialized message
-func (z *LastMinuteLatencies) Msgsize() (s int) {
-	s = 1 + 7 + msgp.ArrayHeaderSize + (60 * (sizeLastElemMarker * (9 + msgp.Int64Size + msgp.Int64Size))) + 8 + msgp.Int64Size
+func (z *lastMinuteLatency) Msgsize() (s int) {
+	s = 1 + 7 + msgp.ArrayHeaderSize + (60 * (9 + msgp.Int64Size + msgp.Int64Size)) + 8 + msgp.Int64Size
 	return
 }

cmd/last-minute_gen_test.go

@@ -234,3 +234,116 @@ func BenchmarkDecodeLastMinuteLatencies(b *testing.B) {
 		}
 	}
 }
+
+func TestMarshalUnmarshallastMinuteLatency(t *testing.T) {
+	v := lastMinuteLatency{}
+	bts, err := v.MarshalMsg(nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	left, err := v.UnmarshalMsg(bts)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(left) > 0 {
+		t.Errorf("%d bytes left over after UnmarshalMsg(): %q", len(left), left)
+	}
+
+	left, err = msgp.Skip(bts)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(left) > 0 {
+		t.Errorf("%d bytes left over after Skip(): %q", len(left), left)
+	}
+}
+
+func BenchmarkMarshalMsglastMinuteLatency(b *testing.B) {
+	v := lastMinuteLatency{}
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		v.MarshalMsg(nil)
+	}
+}
+
+func BenchmarkAppendMsglastMinuteLatency(b *testing.B) {
+	v := lastMinuteLatency{}
+	bts := make([]byte, 0, v.Msgsize())
+	bts, _ = v.MarshalMsg(bts[0:0])
+	b.SetBytes(int64(len(bts)))
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		bts, _ = v.MarshalMsg(bts[0:0])
+	}
+}
+
+func BenchmarkUnmarshallastMinuteLatency(b *testing.B) {
+	v := lastMinuteLatency{}
+	bts, _ := v.MarshalMsg(nil)
+	b.ReportAllocs()
+	b.SetBytes(int64(len(bts)))
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		_, err := v.UnmarshalMsg(bts)
+		if err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+func TestEncodeDecodelastMinuteLatency(t *testing.T) {
+	v := lastMinuteLatency{}
+	var buf bytes.Buffer
+	msgp.Encode(&buf, &v)
+
+	m := v.Msgsize()
+	if buf.Len() > m {
+		t.Log("WARNING: TestEncodeDecodelastMinuteLatency Msgsize() is inaccurate")
+	}
+
+	vn := lastMinuteLatency{}
+	err := msgp.Decode(&buf, &vn)
+	if err != nil {
+		t.Error(err)
+	}
+
+	buf.Reset()
+	msgp.Encode(&buf, &v)
+	err = msgp.NewReader(&buf).Skip()
+	if err != nil {
+		t.Error(err)
+	}
+}
+
+func BenchmarkEncodelastMinuteLatency(b *testing.B) {
+	v := lastMinuteLatency{}
+	var buf bytes.Buffer
+	msgp.Encode(&buf, &v)
+	b.SetBytes(int64(buf.Len()))
+	en := msgp.NewWriter(msgp.Nowhere)
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		v.EncodeMsg(en)
+	}
+	en.Flush()
+}
+
+func BenchmarkDecodelastMinuteLatency(b *testing.B) {
+	v := lastMinuteLatency{}
+	var buf bytes.Buffer
+	msgp.Encode(&buf, &v)
+	b.SetBytes(int64(buf.Len()))
+	rd := msgp.NewEndlessReader(buf.Bytes(), b)
+	dc := msgp.NewReader(rd)
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		err := v.DecodeMsg(dc)
+		if err != nil {
+			b.Fatal(err)
+		}
+	}
+}

cmd/metrics-v2.go

@@ -70,6 +70,7 @@ func init() {
 
 	nodeCollector = newMinioCollectorNode([]*MetricsGroup{
 		getNodeHealthMetrics(),
+		getLocalDiskStorageMetrics(),
 		getCacheMetrics(),
 		getHTTPMetrics(),
 		getNetworkMetrics(),
@@ -157,6 +158,8 @@ const (
 	writeBytes      MetricName = "write_bytes"
 	wcharBytes      MetricName = "wchar_bytes"
 
+	apiLatencyMicroSec MetricName = "latency_us"
+
 	usagePercent MetricName = "update_percent"
 
 	commitInfo  MetricName = "commit_info"
@@ -315,6 +318,16 @@ func getClusterCapacityUsageFreeBytesMD() MetricDescription {
 	}
 }
 
+func getNodeDiskAPILatencyMD() MetricDescription {
+	return MetricDescription{
+		Namespace: nodeMetricNamespace,
+		Subsystem: diskSubsystem,
+		Name:      apiLatencyMicroSec,
+		Help:      "Average last minute latency in µs for disk API storage operations.",
+		Type:      gaugeMetric,
+	}
+}
+
 func getNodeDiskUsedBytesMD() MetricDescription {
 	return MetricDescription{
 		Namespace: nodeMetricNamespace,
@@ -1583,6 +1596,35 @@ func getLocalStorageMetrics() *MetricsGroup {
 				Value:          float64(disk.FreeInodes),
 				VariableLabels: map[string]string{"disk": disk.DrivePath},
 			})
+
+		}
+		return
+	})
+	return mg
+}
+
+func getLocalDiskStorageMetrics() *MetricsGroup {
+	mg := &MetricsGroup{
+		cacheInterval: 3 * time.Second,
+	}
+	mg.RegisterRead(func(ctx context.Context) (metrics []Metric) {
+		objLayer := newObjectLayerFn()
+		// Service not initialized yet
+		if objLayer == nil || globalIsGateway {
+			return
+		}
+
+		metrics = make([]Metric, 0, 50)
+		storageInfo, _ := objLayer.LocalStorageInfo(ctx)
+		for _, disk := range storageInfo.Disks {
+			for apiName, latency := range disk.Metrics.APILatencies {
+				val := latency.(uint64)
+				metrics = append(metrics, Metric{
+					Description:    getNodeDiskAPILatencyMD(),
+					Value:          float64(val / 1000),
+					VariableLabels: map[string]string{"disk": disk.DrivePath, "api": "storage." + apiName},
+				})
+			}
 		}
 		return
 	})

cmd/storage-datatypes.go

@@ -47,7 +47,7 @@ type DiskInfo struct {
 // the number of calls of each API and the moving average of
 // the duration of each API.
 type DiskMetrics struct {
-	APILatencies map[string]string `json:"apiLatencies,omitempty"`
+	APILatencies map[string]uint64 `json:"apiLatencies,omitempty"`
 	APICalls     map[string]uint64 `json:"apiCalls,omitempty"`
 }
 

cmd/storage-datatypes_gen.go

@@ -299,7 +299,7 @@ func (z *DiskMetrics) DecodeMsg(dc *msgp.Reader) (err error) {
 				return
 			}
 			if z.APILatencies == nil {
-				z.APILatencies = make(map[string]string, zb0002)
+				z.APILatencies = make(map[string]uint64, zb0002)
 			} else if len(z.APILatencies) > 0 {
 				for key := range z.APILatencies {
 					delete(z.APILatencies, key)
@@ -308,13 +308,13 @@ func (z *DiskMetrics) DecodeMsg(dc *msgp.Reader) (err error) {
 			for zb0002 > 0 {
 				zb0002--
 				var za0001 string
-				var za0002 string
+				var za0002 uint64
 				za0001, err = dc.ReadString()
 				if err != nil {
 					err = msgp.WrapError(err, "APILatencies")
 					return
 				}
-				za0002, err = dc.ReadString()
+				za0002, err = dc.ReadUint64()
 				if err != nil {
 					err = msgp.WrapError(err, "APILatencies", za0001)
 					return
@@ -381,7 +381,7 @@ func (z *DiskMetrics) EncodeMsg(en *msgp.Writer) (err error) {
 			err = msgp.WrapError(err, "APILatencies")
 			return
 		}
-		err = en.WriteString(za0002)
+		err = en.WriteUint64(za0002)
 		if err != nil {
 			err = msgp.WrapError(err, "APILatencies", za0001)
 			return
@@ -421,7 +421,7 @@ func (z *DiskMetrics) MarshalMsg(b []byte) (o []byte, err error) {
 	o = msgp.AppendMapHeader(o, uint32(len(z.APILatencies)))
 	for za0001, za0002 := range z.APILatencies {
 		o = msgp.AppendString(o, za0001)
-		o = msgp.AppendString(o, za0002)
+		o = msgp.AppendUint64(o, za0002)
 	}
 	// string "APICalls"
 	o = append(o, 0xa8, 0x41, 0x50, 0x49, 0x43, 0x61, 0x6c, 0x6c, 0x73)
@@ -459,7 +459,7 @@ func (z *DiskMetrics) UnmarshalMsg(bts []byte) (o []byte, err error) {
 				return
 			}
 			if z.APILatencies == nil {
-				z.APILatencies = make(map[string]string, zb0002)
+				z.APILatencies = make(map[string]uint64, zb0002)
 			} else if len(z.APILatencies) > 0 {
 				for key := range z.APILatencies {
 					delete(z.APILatencies, key)
@@ -467,14 +467,14 @@ func (z *DiskMetrics) UnmarshalMsg(bts []byte) (o []byte, err error) {
 			}
 			for zb0002 > 0 {
 				var za0001 string
-				var za0002 string
+				var za0002 uint64
 				zb0002--
 				za0001, bts, err = msgp.ReadStringBytes(bts)
 				if err != nil {
 					err = msgp.WrapError(err, "APILatencies")
 					return
 				}
-				za0002, bts, err = msgp.ReadStringBytes(bts)
+				za0002, bts, err = msgp.ReadUint64Bytes(bts)
 				if err != nil {
 					err = msgp.WrapError(err, "APILatencies", za0001)
 					return
@@ -529,7 +529,7 @@ func (z *DiskMetrics) Msgsize() (s int) {
 	if z.APILatencies != nil {
 		for za0001, za0002 := range z.APILatencies {
 			_ = za0002
-			s += msgp.StringPrefixSize + len(za0001) + msgp.StringPrefixSize + len(za0002)
+			s += msgp.StringPrefixSize + len(za0001) + msgp.Uint64Size
 		}
 	}
 	s += 9 + msgp.MapHeaderSize

cmd/xl-storage-disk-id-check.go

@@ -25,7 +25,6 @@ import (
 	"sync/atomic"
 	"time"
 
-	"github.com/VividCortex/ewma"
 	"github.com/minio/madmin-go"
 )
 
@@ -71,18 +70,18 @@ type xlStorageDiskIDCheck struct {
 	// please use `fieldalignment ./...` to check
 	// if your changes are not causing any problems.
 	storage      StorageAPI
-	apiLatencies [storageMetricLast]ewma.MovingAverage
+	apiLatencies [storageMetricLast]*lockedLastMinuteLatency
 	diskID       string
 	apiCalls     [storageMetricLast]uint64
 }
 
 func (p *xlStorageDiskIDCheck) getMetrics() DiskMetrics {
 	diskMetric := DiskMetrics{
-		APILatencies: make(map[string]string),
+		APILatencies: make(map[string]uint64),
 		APICalls:     make(map[string]uint64),
 	}
 	for i, v := range p.apiLatencies {
-		diskMetric.APILatencies[storageMetric(i).String()] = time.Duration(v.Value()).String()
+		diskMetric.APILatencies[storageMetric(i).String()] = v.value()
 	}
 	for i := range p.apiCalls {
 		diskMetric.APICalls[storageMetric(i).String()] = atomic.LoadUint64(&p.apiCalls[i])
@@ -90,28 +89,21 @@ func (p *xlStorageDiskIDCheck) getMetrics() DiskMetrics {
 	return diskMetric
 }
 
-type lockedSimpleEWMA struct {
-	sync.RWMutex
-	*ewma.SimpleEWMA
+type lockedLastMinuteLatency struct {
+	sync.Mutex
+	lastMinuteLatency
 }
 
-func (e *lockedSimpleEWMA) Add(value float64) {
+func (e *lockedLastMinuteLatency) add(value time.Duration) {
 	e.Lock()
 	defer e.Unlock()
-	e.SimpleEWMA.Add(value)
+	e.lastMinuteLatency.add(value)
 }
 
-func (e *lockedSimpleEWMA) Set(value float64) {
+func (e *lockedLastMinuteLatency) value() uint64 {
 	e.Lock()
 	defer e.Unlock()
-
-	e.SimpleEWMA.Set(value)
-}
-
-func (e *lockedSimpleEWMA) Value() float64 {
-	e.RLock()
-	defer e.RUnlock()
-	return e.SimpleEWMA.Value()
+	return e.lastMinuteLatency.getAvgData().avg()
 }
 
 func newXLStorageDiskIDCheck(storage *xlStorage) *xlStorageDiskIDCheck {
@@ -119,9 +111,7 @@ func newXLStorageDiskIDCheck(storage *xlStorage) *xlStorageDiskIDCheck {
 		storage: storage,
 	}
 	for i := range xl.apiLatencies[:] {
-		xl.apiLatencies[i] = &lockedSimpleEWMA{
-			SimpleEWMA: new(ewma.SimpleEWMA),
-		}
+		xl.apiLatencies[i] = &lockedLastMinuteLatency{}
 	}
 	return &xl
 }
@@ -582,7 +572,7 @@ func (p *xlStorageDiskIDCheck) updateStorageMetrics(s storageMetric, paths ...st
 		duration := time.Since(startTime)
 
 		atomic.AddUint64(&p.apiCalls[s], 1)
-		p.apiLatencies[s].Add(float64(duration))
+		p.apiLatencies[s].add(duration)
 
 		if trace {
 			globalTrace.Publish(storageTrace(s, startTime, duration, strings.Join(paths, " ")))