collector/ethtool: skip full scan of NetClass directories (#3239)

wjordan · web-flow · commit edc40d1e0b67 · 2025-02-15T09:32:59.000+01:00
ethtool only uses the device names from `NetClassDevices()`,
not the whole NetClass data from `NetClass()`.
Improves ethtool collector performance on systems with lots of excluded devices.

Signed-off-by: Will Jordan &lt;will.jordan@gmail.com&gt;
diff --git a/collector/ethtool_linux.go b/collector/ethtool_linux.go
@@ -372,7 +372,7 @@ func (c *ethtoolCollector) updateSpeeds(ch chan<- prometheus.Metric, prefix stri
 }
 
 func (c *ethtoolCollector) Update(ch chan<- prometheus.Metric) error {
-	netClass, err := c.fs.NetClass()
+	netClass, err := c.fs.NetClassDevices()
 	if err != nil {
 		if errors.Is(err, os.ErrNotExist) || errors.Is(err, os.ErrPermission) {
 			c.logger.Debug("Could not read netclass file", "err", err)
@@ -385,7 +385,7 @@ func (c *ethtoolCollector) Update(ch chan<- prometheus.Metric) error {
 		return fmt.Errorf("no network devices found")
 	}
 
-	for device := range netClass {
+	for _, device := range netClass {
 		var stats map[string]uint64
 		var err error
 

Original file line number	Diff line number	Diff line change
`@@ -372,7 +372,7 @@ func (c *ethtoolCollector) updateSpeeds(ch chan<- prometheus.Metric, prefix stri`
`372`	`372`	`}`
`373`	`373`
`374`	`374`	`func (c *ethtoolCollector) Update(ch chan<- prometheus.Metric) error {`
`375`		`- netClass, err := c.fs.NetClass()`
	`375`	`+ netClass, err := c.fs.NetClassDevices()`
`376`	`376`	`if err != nil {`
`377`	`377`	`if errors.Is(err, os.ErrNotExist) \|\| errors.Is(err, os.ErrPermission) {`
`378`	`378`	`c.logger.Debug("Could not read netclass file", "err", err)`
`@@ -385,7 +385,7 @@ func (c *ethtoolCollector) Update(ch chan<- prometheus.Metric) error {`
`385`	`385`	`return fmt.Errorf("no network devices found")`
`386`	`386`	`}`
`387`	`387`
`388`		`- for device := range netClass {`
	`388`	`+ for _, device := range netClass {`
`389`	`389`	`var stats map[string]uint64`
`390`	`390`	`var err error`
`391`	`391`