func (pl *ProberList) addProber(genericProber prober.Prober, path string,
probeInterval uint8) {
newProber := &proberType{
prober: genericProber,
probeInterval: time.Duration(probeInterval) * time.Second,
probeTimeDistribution: latencyBucketer.NewCumulativeDistribution(),
}
if err := tricorder.RegisterMetric(pl.proberPath+path+"/probe-duration",
newProber.probeTimeDistribution, units.Millisecond,
"duration of last probe"); err != nil {
panic(err)
}
if probeInterval > 0 {
if err := tricorder.RegisterMetric(pl.proberPath+path+"/probe-interval",
&newProber.probeInterval, units.Second,
"probe interval"); err != nil {
panic(err)
}
if err := tricorder.RegisterMetric(
pl.proberPath+path+"/probe-start-time",
&newProber.probeStartTime, units.None,
"start time of last probe"); err != nil {
panic(err)
}
}
pl.probers = append(pl.probers, newProber)
}
func init() {
latencyBucketer = tricorder.NewGeometricBucketer(0.1, 100e3)
mdbCompareTimeDistribution = latencyBucketer.NewDistribution()
tricorder.RegisterMetric("/mdb-compare-time", mdbCompareTimeDistribution,
units.Millisecond, "time to compare new MDB with old MDB")
mdbDecodeTimeDistribution = latencyBucketer.NewDistribution()
tricorder.RegisterMetric("/mdb-decode-time", mdbDecodeTimeDistribution,
units.Millisecond, "time to decode MDB data")
mdbSortTimeDistribution = latencyBucketer.NewDistribution()
tricorder.RegisterMetric("/mdb-sort-time", mdbSortTimeDistribution,
units.Millisecond, "time to sort MDB data")
}
func init() {
loadCpuTimeDistribution = latencyBucketer.NewCumulativeDistribution()
if err := tricorder.RegisterMetric("/load-cpu-time", loadCpuTimeDistribution,
units.Millisecond, "load CPU time durations"); err != nil {
panic(err)
}
loadTimeDistribution = latencyBucketer.NewCumulativeDistribution()
if err := tricorder.RegisterMetric("/load-time", loadTimeDistribution,
units.Millisecond, "load durations"); err != nil {
panic(err)
}
}
func init() {
latencyBucketer = tricorder.NewGeometricBucketer(0.1, 100e3)
computeCpuTimeDistribution = latencyBucketer.NewDistribution()
tricorder.RegisterMetric("/compute-cputime", computeCpuTimeDistribution,
units.Millisecond, "compute CPU time")
fullPollDistribution = latencyBucketer.NewDistribution()
tricorder.RegisterMetric("/poll-full-latency", fullPollDistribution,
units.Millisecond, "full poll duration")
mdbUpdateTimeDistribution = latencyBucketer.NewDistribution()
tricorder.RegisterMetric("/mdb-update-time", mdbUpdateTimeDistribution,
units.Millisecond, "time to update Herd MDB data")
shortPollDistribution = latencyBucketer.NewDistribution()
tricorder.RegisterMetric("/poll-short-latency", shortPollDistribution,
units.Millisecond, "short poll duration")
}
func main() {
flag.Parse()
tricorder.RegisterFlags()
if os.Geteuid() == 0 {
fmt.Fprintln(os.Stderr, "Do not run the Image Server as root")
os.Exit(1)
}
setupTls(*caFile, *certFile, *keyFile)
circularBuffer := logbuf.New(*logbufLines)
logger := log.New(circularBuffer, "", log.LstdFlags)
objSrv, err := filesystem.NewObjectServer(*objectDir, logger)
if err != nil {
fmt.Fprintf(os.Stderr, "Cannot create ObjectServer\t%s\n", err)
os.Exit(1)
}
imdb, err := scanner.LoadImageDataBase(*imageDir, objSrv, logger)
if err != nil {
fmt.Fprintf(os.Stderr, "Cannot load image database\t%s\n", err)
os.Exit(1)
}
tricorder.RegisterMetric("/image-count",
func() uint { return imdb.CountImages() },
units.None, "number of images")
imageserverRpcd.Setup(imdb, logger)
rpcHtmlWriter := objectserverRpcd.Setup(objSrv, logger)
rpc.HandleHTTP()
httpd.AddHtmlWriter(imdb)
httpd.AddHtmlWriter(rpcHtmlWriter)
httpd.AddHtmlWriter(circularBuffer)
if err = httpd.StartServer(*portNum, imdb, false); err != nil {
fmt.Fprintf(os.Stderr, "Unable to create http server\t%s\n", err)
os.Exit(1)
}
}
func Setup(configuration *scanner.Configuration, fsh *scanner.FileSystemHistory,
objectsDirname string, rootDirname string,
netReaderContext *rateio.ReaderContext,
netbenchFname string, oldTriggersFname string,
disableScannerFunction func(disableScanner bool),
rescanObjectCacheFunction func(), logger *log.Logger) *HtmlWriter {
rpcObj := &rpcType{
scannerConfiguration: configuration,
fileSystemHistory: fsh,
objectsDir: objectsDirname,
rootDir: rootDirname,
networkReaderContext: netReaderContext,
netbenchFilename: netbenchFname,
oldTriggersFilename: oldTriggersFname,
rescanObjectCacheFunction: rescanObjectCacheFunction,
disableScannerFunc: disableScannerFunction,
logger: logger}
srpc.RegisterName("Subd", rpcObj)
addObjectsHandler := &addObjectsHandlerType{
objectsDir: objectsDirname,
logger: logger}
srpc.RegisterName("ObjectServer", addObjectsHandler)
tricorder.RegisterMetric("/image-name", &rpcObj.lastSuccessfulImageName,
units.None, "name of the image for the last successful update")
return &HtmlWriter{&rpcObj.lastSuccessfulImageName}
}
func newProberList(proberPath string) *ProberList {
pl := &ProberList{
proberPath: proberPath,
probeTimeDistribution: latencyBucketer.NewCumulativeDistribution(),
}
if err := tricorder.RegisterMetric(proberPath+"/probe-duration",
pl.probeTimeDistribution, units.Millisecond,
"duration of last probe"); err != nil {
panic(err)
}
if err := tricorder.RegisterMetric(proberPath+"/probe-start-time",
&pl.probeStartTime, units.None,
"start time of last probe"); err != nil {
panic(err)
}
return pl
}
func init() {
statisticsComputeBucketer = tricorder.NewGeometricBucketer(0.1, 100e3)
statisticsComputeCpuTimeDistribution =
statisticsComputeBucketer.NewCumulativeDistribution()
tricorder.RegisterMetric("/statistics-compute-cputime",
statisticsComputeCpuTimeDistribution,
units.Millisecond, "statistics compute CPU time")
}
func main() {
flag.Parse()
tricorder.RegisterFlags()
if os.Geteuid() == 0 {
fmt.Fprintln(os.Stderr, "Do not run the Image Server as root")
os.Exit(1)
}
if *archiveMode && *imageServerHostname == "" {
fmt.Fprintln(os.Stderr, "-imageServerHostname required in archive mode")
os.Exit(1)
}
circularBuffer := logbuf.New()
logger := log.New(circularBuffer, "", log.LstdFlags)
if err := setupserver.SetupTls(); err != nil {
logger.Println(err)
circularBuffer.Flush()
if !*permitInsecureMode {
os.Exit(1)
}
}
objSrv, err := filesystem.NewObjectServer(*objectDir, logger)
if err != nil {
fmt.Fprintf(os.Stderr, "Cannot create ObjectServer: %s\n", err)
os.Exit(1)
}
cleanupUnreferencedObjects := true
if *imageServerHostname != "" {
cleanupUnreferencedObjects = false
}
imdb, err := scanner.LoadImageDataBase(*imageDir, objSrv,
cleanupUnreferencedObjects, logger)
if err != nil {
fmt.Fprintf(os.Stderr, "Cannot load image database: %s\n", err)
os.Exit(1)
}
tricorder.RegisterMetric("/image-count",
func() uint { return imdb.CountImages() },
units.None, "number of images")
imgSrvRpcHtmlWriter := imageserverRpcd.Setup(imdb, *imageServerHostname,
logger)
objSrvRpcHtmlWriter := objectserverRpcd.Setup(objSrv, logger)
httpd.AddHtmlWriter(imdb)
httpd.AddHtmlWriter(&imageObjectServersType{imdb, objSrv})
httpd.AddHtmlWriter(imgSrvRpcHtmlWriter)
httpd.AddHtmlWriter(objSrvRpcHtmlWriter)
httpd.AddHtmlWriter(circularBuffer)
if *imageServerHostname != "" {
go replicator(fmt.Sprintf("%s:%d", *imageServerHostname,
*imageServerPortNum), imdb, objSrv, *archiveMode, logger)
}
if err = httpd.StartServer(*portNum, imdb, objSrv, false); err != nil {
fmt.Fprintf(os.Stderr, "Unable to create http server: %s\n", err)
os.Exit(1)
}
}
func Setup(objSrv objectserver.ObjectServer, logger *log.Logger) *htmlWriter {
getSemaphore := make(chan bool, 100)
rpcObj := &objectServer{objSrv}
srpcObj := &srpcType{objSrv, getSemaphore, logger}
rpc.RegisterName("ObjectServer", rpcObj)
srpc.RegisterName("ObjectServer", srpcObj)
tricorder.RegisterMetric("/get-requests",
func() uint { return uint(len(getSemaphore)) },
units.None, "number of GetObjects() requests in progress")
return &htmlWriter{getSemaphore}
}
func doMain() error {
flag.Parse()
runtime.GOMAXPROCS(int(*maxThreads))
runtime.LockOSThread()
circularBuffer := logbuf.New(*logbufLines)
logger := log.New(circularBuffer, "", log.LstdFlags)
probers, err := setupProbers()
if err != nil {
return err
}
latencyBucketer := tricorder.NewGeometricBucketer(0.1, 100e3)
scanTimeDistribution := latencyBucketer.NewDistribution()
var scanStartTime time.Time
if err := tricorder.RegisterMetric("scan-duration",
scanTimeDistribution, units.Millisecond,
"duration of last probe"); err != nil {
return err
}
if err := tricorder.RegisterMetric("scan-start-time", &scanStartTime,
units.None, "start time of last probe"); err != nil {
return err
}
rpc.HandleHTTP()
httpd.AddHtmlWriter(circularBuffer)
if err := httpd.StartServer(*portNum); err != nil {
return err
}
for {
scanStartTime = time.Now()
for _, p := range probers {
if err := p.Probe(); err != nil {
logger.Println(err)
}
}
scanDuration := time.Since(scanStartTime)
scanTimeDistribution.Add(scanDuration)
time.Sleep(time.Second*time.Duration(*probeInterval) - scanDuration)
}
_ = logger
return nil
}
func init() {
tricorder.RegisterMetric("/get-requests",
func() uint { return uint(len(getSemaphore)) },
units.None, "number of GetObjects() requests in progress")
}
func makeMetric(bucketer *tricorder.Bucketer, name string,
comment string) *tricorder.CumulativeDistribution {
distribution := latencyBucketer.NewCumulativeDistribution()
tricorder.RegisterMetric(name, distribution, units.Millisecond, comment)
return distribution
}
func registerMetrics() {
var temperature float64
var someBool bool
var someDuration time.Duration
rpcDistribution := tricorder.PowersOfTen.NewCumulativeDistribution()
var sample []int
kAnIntList = tricorder.NewList(sample, tricorder.MutableSlice)
if err := tricorder.RegisterMetric(
"/list/squares",
kAnIntList,
units.None,
"Squares"); err != nil {
log.Fatalf("Got error %v registering metric", err)
}
if err := tricorder.RegisterMetric(
"/proc/rpc-latency",
rpcDistribution,
units.Millisecond,
"RPC latency"); err != nil {
log.Fatalf("Got error %v registering metric", err)
}
if err := tricorder.RegisterMetric(
"/proc/rpc-count",
rpcCountCallback,
units.Unknown,
"RPC count"); err != nil {
log.Fatalf("Got error %v registering metric", err)
}
if err := tricorder.RegisterMetric("/proc/temperature", &temperature, units.Celsius, "Temperature"); err != nil {
log.Fatalf("Got error %v registering metric", err)
}
if err := tricorder.RegisterMetric("/proc/duration", &someDuration, units.Second, "Duration"); err != nil {
log.Fatalf("Got error %v registering metric", err)
}
fooDir, err := tricorder.RegisterDirectory("proc/foo")
if err != nil {
log.Fatalf("Got error %v registering directory", err)
}
barDir, err := fooDir.RegisterDirectory("bar")
if err != nil {
log.Fatalf("Got error %v registering directory", err)
}
err = barDir.RegisterMetric(
"baz",
bazCallback,
units.None,
"Another float value")
if err != nil {
log.Fatalf("Got error %v registering metric", err)
}
err = barDir.RegisterMetric("abool", &someBool, units.None, "A boolean value")
if err != nil {
log.Fatalf("Got error %v registering metric", err)
}
temperature = 22.5
someBool = true
someDuration = 2*time.Minute + 5*time.Second
// Add data points to the distribution
// < 10: 10
// 10 - 25: 15
// 25 - 62.5: 38
// 62.5 - 156.25: 94
// 156.25 - 390.625: 234
for i := 0; i < 500; i++ {
rpcDistribution.Add(float64(i))
}
go updateList()
}
func init() {
latencyBucketer = tricorder.NewGeometricBucketer(1, 100e3)
scanTimeDistribution = latencyBucketer.NewDistribution()
tricorder.RegisterMetric("/scan-time", scanTimeDistribution,
units.Second, "scan time")
}
func startCollector(
appStats *datastructs.ApplicationStatuses,
connectionErrors *connectionErrorsType,
totalCounts totalCountUpdaterType,
metricNameAdder suggest.Adder,
memoryChecker memoryCheckerType) {
collector.SetConcurrentPolls(*fPollCount)
collector.SetConcurrentConnects(*fConnectionCount)
sweepDurationDist := tricorder.NewGeometricBucketer(1, 100000.0).NewCumulativeDistribution()
collectionBucketer := tricorder.NewGeometricBucketer(1e-4, 100.0)
collectionTimesDist := collectionBucketer.NewCumulativeDistribution()
tricorderCollectionTimesDist := collectionBucketer.NewCumulativeDistribution()
snmpCollectionTimesDist := collectionBucketer.NewCumulativeDistribution()
jsonCollectionTimesDist := collectionBucketer.NewCumulativeDistribution()
changedMetricsPerEndpointDist := tricorder.NewGeometricBucketer(1.0, 10000.0).NewCumulativeDistribution()
if err := tricorder.RegisterMetric(
"collector/collectionTimes",
collectionTimesDist,
units.Second,
"Collection Times"); err != nil {
log.Fatal(err)
}
if err := tricorder.RegisterMetric(
"collector/collectionTimes_tricorder",
tricorderCollectionTimesDist,
units.Second,
"Tricorder Collection Times"); err != nil {
log.Fatal(err)
}
if err := tricorder.RegisterMetric(
"collector/collectionTimes_snmp",
snmpCollectionTimesDist,
units.Second,
"SNMP Collection Times"); err != nil {
log.Fatal(err)
}
if err := tricorder.RegisterMetric(
"collector/collectionTimes_json",
jsonCollectionTimesDist,
units.Second,
"JSON Collection Times"); err != nil {
log.Fatal(err)
}
if err := tricorder.RegisterMetric(
"collector/changedMetricsPerEndpoint",
changedMetricsPerEndpointDist,
units.None,
"Changed metrics per sweep"); err != nil {
log.Fatal(err)
}
if err := tricorder.RegisterMetric(
"collector/sweepDuration",
sweepDurationDist,
units.Millisecond,
"Sweep duration"); err != nil {
log.Fatal(err)
}
programStartTime := time.Now()
if err := tricorder.RegisterMetric(
"collector/elapsedTime",
func() time.Duration {
return time.Now().Sub(programStartTime)
},
units.Second,
"elapsed time"); err != nil {
log.Fatal(err)
}
byProtocolDist := map[string]*tricorder.CumulativeDistribution{
"tricorder": tricorderCollectionTimesDist,
"snmp": snmpCollectionTimesDist,
"json": jsonCollectionTimesDist,
}
// Metric collection goroutine. Collect metrics periodically.
go func() {
// We assign each endpoint its very own nameSetType instance
// to store metric names already sent to suggest.
// Only that endpoint's fetch goroutine reads and modifies
// the contents of its nameSetType instance. Although
// this goroutine creates nameSetType instances and manages
// the references to them, it never reads or modifies the
// contents of any nameSetType instance after creating it.
endpointToNamesSentToSuggest := make(
map[*collector.Endpoint]nameSetType)
for {
endpoints, metricStore := appStats.ActiveEndpointIds()
sweepTime := time.Now()
for _, endpoint := range endpoints {
namesSentToSuggest := endpointToNamesSentToSuggest[endpoint]
if namesSentToSuggest == nil {
namesSentToSuggest = make(nameSetType)
endpointToNamesSentToSuggest[endpoint] = namesSentToSuggest
}
logger := &loggerType{
Store: metricStore,
AppStats: appStats,
ConnectionErrors: connectionErrors,
CollectionTimesDist: collectionTimesDist,
ByProtocolDist: byProtocolDist,
ChangedMetricsDist: changedMetricsPerEndpointDist,
NamesSentToSuggest: namesSentToSuggest,
MetricNameAdder: metricNameAdder,
TotalCounts: totalCounts,
}
endpoint.Poll(sweepTime, logger)
}
sweepDuration := time.Now().Sub(sweepTime)
sweepDurationDist.Add(sweepDuration)
memoryChecker.Check()
if sweepDuration < *fCollectionFrequency {
time.Sleep((*fCollectionFrequency) - sweepDuration)
}
}
}()
}
// RegisterMetrics registers the memory manager metrics
func (m *memoryManagerType) RegisterMetrics() (err error) {
var data memoryManagerMetricsType
group := tricorder.NewGroup()
group.RegisterUpdateFunc(
func() time.Time {
m.Metrics(&data)
return time.Now()
})
if err = tricorder.RegisterMetricInGroup(
"/proc/memory-manager/alloc-bytes-needed-for-gc",
&data.AllocBytesNeededForGC,
group,
units.Byte,
"Number of allocated bytes needed to trigger GC"); err != nil {
return
}
if err = tricorder.RegisterMetricInGroup(
"/proc/memory-manager/largest-alloc-bytes-needed-for-gc",
&data.LargestAllocBytesNeededForGC,
group,
units.Byte,
"Number of allocated bytes needed to trigger GC"); err != nil {
return
}
if err = tricorder.RegisterMetricInGroup(
"/proc/memory-manager/inspected-cycle-count",
&data.InspectedCycleCount,
group,
units.None,
"Number of gc cycles inspected"); err != nil {
return
}
if err = tricorder.RegisterMetricInGroup(
"/proc/memory-manager/total-cycle-count",
&data.TotalCycleCount,
group,
units.None,
"Number of total gc cycles"); err != nil {
return
}
if err = tricorder.RegisterMetricInGroup(
"/proc/memory-manager/stw-gc-count",
&data.STWGCCount,
group,
units.None,
"Number of stop the world GCs"); err != nil {
return
}
if err = tricorder.RegisterMetricInGroup(
"/proc/memory-manager/no-expand-count",
&data.NoExpandCount,
group,
units.None,
"Inspected cycle counts where we disabled expanding"); err != nil {
return
}
if err = tricorder.RegisterMetricInGroup(
"/proc/memory-manager/page-free-bytes",
&data.PageFreeInBytes,
group,
units.Byte,
"Total number of pages freed in bytes"); err != nil {
return
}
if err = tricorder.RegisterMetricInGroup(
"/proc/memory-manager/page-free-count",
&data.PageFreeCount,
group,
units.None,
"Number of times pages freed"); err != nil {
return
}
if err = tricorder.RegisterMetric(
"proc/memory-manager/hard-limit",
&m.hardLimit,
units.Byte,
"Target memory usage"); err != nil {
return
}
if err = tricorder.RegisterMetric(
"proc/memory-manager/high-water-mark",
&m.highWaterMark,
units.Byte,
"Memory usage that triggers a GC"); err != nil {
return
}
if err = tricorder.RegisterMetric(
"proc/memory-manager/low-water-mark",
&m.lowWaterMark,
units.Byte,
"Desired memory usage after GC happens"); err != nil {
return
}
if err = tricorder.RegisterMetric(
"proc/memory-manager/gc-percent",
&m.gcPercent,
units.None,
"GC percentage"); err != nil {
return
}
return
}
func (p *pstoreHandlerType) RegisterMetrics() (err error) {
var attributes pstore.ConsumerAttributes
p.consumer.Attributes(&attributes)
var data pstore.ConsumerMetrics
var visitorData visitorMetricsType
metricsStore := p.ConsumerMetricsStore()
visitorMetricsStore := p.visitorMetricsStore
group := tricorder.NewGroup()
group.RegisterUpdateFunc(
func() time.Time {
metricsStore.Metrics(&data)
visitorMetricsStore.Metrics(&visitorData)
return time.Now()
})
if err = tricorder.RegisterMetric(
fmt.Sprintf("writer/%s/totalTimeSpent", p.Name()),
p.totalTimeSpentDist,
units.Second,
"total time spent per sweep"); err != nil {
return
}
if err = tricorder.RegisterMetric(
fmt.Sprintf("writer/%s/writeTimePerMetric", p.Name()),
p.perMetricWriteTimes,
units.Millisecond,
"Time spent writing each metric"); err != nil {
return
}
if err = tricorder.RegisterMetric(
fmt.Sprintf("writer/%s/maxRecordsPerSecond", p.Name()),
attributes.TotalRecordsPerSecond,
units.None,
"Max records per second to write. 0 means unlimited"); err != nil {
return
}
if err = tricorder.RegisterMetric(
fmt.Sprintf("writer/%s/concurrency", p.Name()),
&attributes.Concurrency,
units.None,
"Number of writing goroutines"); err != nil {
return
}
if err = tricorder.RegisterMetric(
fmt.Sprintf("writer/%s/batchSize", p.Name()),
&attributes.BatchSize,
units.None,
"This many records written each time"); err != nil {
return
}
if err = tricorder.RegisterMetric(
fmt.Sprintf("writer/%s/rollUpSpan", p.Name()),
&attributes.RollUpSpan,
units.None,
"Time period length for rolled up values. 0 means no roll up."); err != nil {
return
}
if err = tricorder.RegisterMetricInGroup(
fmt.Sprintf("writer/%s/valuesWritten", p.Name()),
&data.ValuesWritten,
group,
units.None,
"Number of values written to persistent storage"); err != nil {
return
}
if err = tricorder.RegisterMetricInGroup(
fmt.Sprintf("writer/%s/valuesNotWritten", p.Name()),
&data.ValuesNotWritten,
group,
units.None,
"Number of values not written to persistent storage"); err != nil {
return
}
if err = tricorder.RegisterMetricInGroup(
fmt.Sprintf("writer/%s/timeLeft", p.Name()),
&visitorData.TimeLeft,
group,
units.None,
"approximate time writer is behind"); err != nil {
return
}
if err = tricorder.RegisterMetricInGroup(
fmt.Sprintf("writer/%s/blocked", p.Name()),
&visitorData.Blocked,
group,
units.None,
"true if writer is awaiting a lease"); err != nil {
return
}
if err = tricorder.RegisterMetricInGroup(
fmt.Sprintf("writer/%s/writeAttempts", p.Name()),
&data.WriteAttempts,
group,
units.None,
"Number of attempts to write to persistent storage"); err != nil {
return
}
if err = tricorder.RegisterMetricInGroup(
fmt.Sprintf("writer/%s/successfulWrites", p.Name()),
&data.SuccessfulWrites,
group,
units.None,
"Number of successful writes to persistent storage"); err != nil {
return
}
if err = tricorder.RegisterMetricInGroup(
fmt.Sprintf("writer/%s/successfulWriteRatio", p.Name()),
data.SuccessfulWriteRatio,
group,
units.None,
"Ratio of successful writes to write attempts"); err != nil {
return
}
if err = tricorder.RegisterMetricInGroup(
fmt.Sprintf("writer/%s/lastWriteError", p.Name()),
&data.LastWriteError,
group,
units.None,
"Last write error"); err != nil {
return
}
if err = tricorder.RegisterMetricInGroup(
fmt.Sprintf("writer/%s/lastWriteErrorTime", p.Name()),
&data.LastWriteErrorTS,
group,
units.None,
"Time of last write error"); err != nil {
return
}
if err = tricorder.RegisterMetricInGroup(
fmt.Sprintf("writer/%s/lastSuccessfulWrite", p.Name()),
&data.LastSuccessfulWriteTS,
group,
units.None,
"Time of last successful write"); err != nil {
return
}
return
}
func publishFsSpeed(bytesPerSecond, blocksPerSecond uint64) {
tricorder.RegisterMetric("/root-read-speed", &bytesPerSecond,
units.BytePerSecond, "read speed of root file-system media")
tricorder.RegisterMetric("/root-block-read-speed", &blocksPerSecond,
units.None, "read speed of root file-system media in blocks/second")
}