Cherry-pick #14271 to 7.x: Convert ticks to milliseconds for diskio m…

…etricset (#16797)

* Convert ticks to milliseconds for diskio (#14271)


(cherry picked from commit 8892766)

* changelog

* remove space

CHANGELOG.next.asciidoc

@@ -150,6 +150,7 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Revert changes in `docker` module: add size flag to docker.container. {pull}16600[16600]
 - Fix detection and logging of some error cases with light modules. {pull}14706[14706]
 - Add dashboard for `redisenterprise` module. {pull}16752[16752]
+- Convert increments of 100 nanoseconds/ticks to milliseconds for WriteTime and ReadTime in diskio metricset (Windows) for consistency. {issue}14233[14233]
 
 *Packetbeat*
 

metricbeat/module/system/diskio/diskstat_windows_helper.go

@@ -50,10 +50,13 @@ type logicalDrive struct {
 }
 
 type diskPerformance struct {
-	BytesRead           int64
-	BytesWritten        int64
-	ReadTime            int64
-	WriteTime           int64
+	BytesRead    int64
+	BytesWritten int64
+	// Contains a cumulative time, expressed in increments of 100 nanoseconds (or ticks).
+	ReadTime int64
+	// Contains a cumulative time, expressed in increments of 100 nanoseconds (or ticks).
+	WriteTime int64
+	//Contains a cumulative time, expressed in increments of 100 nanoseconds (or ticks).
 	IdleTime            int64
 	ReadCount           uint32
 	WriteCount          uint32
@@ -95,8 +98,9 @@ func ioCounters(names ...string) (map[string]disk.IOCountersStat, error) {
 			WriteCount: uint64(counter.WriteCount),
 			ReadBytes:  uint64(counter.BytesRead),
 			WriteBytes: uint64(counter.BytesWritten),
-			ReadTime:   uint64(counter.ReadTime),
-			WriteTime:  uint64(counter.WriteTime),
+			// Ticks (which is equal to 100 nanoseconds) will be converted to milliseconds for consistency reasons for both ReadTime and WriteTime (https://docs.microsoft.com/en-us/dotnet/api/system.timespan.ticks?redirectedfrom=MSDN&view=netframework-4.8#remarks)
+			ReadTime:  uint64(counter.ReadTime / 10000),
+			WriteTime: uint64(counter.WriteTime / 10000),
 		}
 	}
 	return ret, nil