add memory stats

app/proc/drivers/rapl.go

@@ -0,0 +1,123 @@
+package drivers
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+)
+
+const milliJoulePerJoule = float64(1000000)
+
+type EnergyState struct {
+	lastEnergy uint64
+	lastTime   time.Time
+}
+
+type RaplDriver struct {
+	energyState map[string]EnergyState
+}
+
+func NewRaplDriver() *RaplDriver {
+	return &RaplDriver{
+		energyState: map[string]EnergyState{},
+	}
+
+}
+
+func (r *RaplDriver) ReadPowerSensors() ([]PowerSensor, error) {
+	powerSensors := []PowerSensor{}
+
+	patterns := []string{
+		"/sys/class/powercap/intel-rapl*/energy_uj",
+		"/sys/class/powercap/intel-rapl/intel-rapl*/energy_uj",
+		"/sys/class/powercap/intel-rapl/intel-rapl*/*/energy_uj",
+		"/sys/class/powercap/intel-rapl:*/energy_uj",
+		"/sys/class/powercap/intel-rapl:*/*/energy_uj",
+	}
+
+	energyInputs := []string{}
+	unique := make(map[string]bool)
+
+	for _, pattern := range patterns {
+		matches, _ := filepath.Glob(pattern)
+
+		for _, match := range matches {
+			realPath, err := filepath.EvalSymlinks(match)
+			if err != nil {
+				realPath = match
+			}
+			if !unique[realPath] {
+				unique[realPath] = true
+				energyInputs = append(energyInputs, realPath)
+			}
+		}
+	}
+
+	if len(energyInputs) == 0 {
+		return powerSensors, fmt.Errorf("found no compatible rapl drivers")
+	}
+
+	r.calculateEnergyDelta(energyInputs, &powerSensors)
+	return powerSensors, nil
+}
+
+func getRaplLabel(inputPath string) string {
+	dir := filepath.Dir(inputPath)
+	if nameBytes, err := os.ReadFile(filepath.Join(dir, "name")); err == nil {
+		return strings.TrimSpace(string(nameBytes))
+	}
+	return filepath.Base(dir)
+}
+
+func (r *RaplDriver) calculateEnergyDelta(inputs []string, out *[]PowerSensor) {
+	for _, path := range inputs {
+		now := time.Now()
+		valBytes, err := os.ReadFile(path)
+		if err != nil {
+			continue
+		}
+
+		microJoules, err := strconv.ParseUint(strings.TrimSpace(string(valBytes)), 10, 64)
+		if err != nil {
+			continue
+		}
+
+		sensorLabel := getRaplLabel(path)
+
+		prevState, exists := r.energyState[path]
+
+		if !exists {
+
+			r.energyState[path] = EnergyState{
+				lastEnergy: microJoules,
+				lastTime:   now,
+			}
+			*out = append(*out, PowerSensor{
+				Name:  sensorLabel,
+				Watts: 0.0,
+			})
+			continue
+		}
+
+		timeDiff := now.Sub(prevState.lastTime).Seconds()
+
+		// technically the energy counter could overflow, at ~18 TerraJoules
+		// the value will be off for that one measurement, then become correct again
+		energyDiff := float64(microJoules - prevState.lastEnergy)
+
+		watts := (energyDiff / milliJoulePerJoule) / timeDiff
+
+		r.energyState[path] = EnergyState{
+			lastEnergy: microJoules,
+			lastTime:   now,
+		}
+
+		*out = append(*out, PowerSensor{
+			Name:  sensorLabel,
+			Watts: watts,
+		})
+	}
+}