CPUPercent

cpu.go

@@ -3,6 +3,7 @@ package gopsutil
 import (
 	"encoding/json"
 	"runtime"
+	"time"
 )
 
 type CPUTimesStat struct {
@@ -39,6 +40,57 @@ func CPUCounts(logical bool) (int, error) {
 	return runtime.NumCPU(), nil
 }
 
+var lastCPUTimes []CPUTimesStat
+var lastPerCPUTimes []CPUTimesStat
+
+func CPUPercent(interval time.Duration, percpu bool) ([]float32, error) {
+	getAllBusy := func(t CPUTimesStat) (float32, float32) {
+		busy := t.User + t.System + t.Nice + t.Iowait + t.Irq +
+			t.Softirq + t.Steal + t.Guest + t.GuestNice + t.Stolen
+		return busy + t.Idle, busy
+	}
+
+	calculate := func(t1, t2 CPUTimesStat) float32 {
+		t1All, t1Busy := getAllBusy(t1)
+		t2All, t2Busy := getAllBusy(t2)
+
+		if t2Busy <= t1Busy {
+			return 0
+		}
+		return (t2Busy - t1Busy) / (t2All - t1All) * 100
+	}
+
+	cpuTimes, err := CPUTimes(percpu)
+	if err != nil {
+		return nil, err
+	}
+
+	if interval > 0 {
+		if !percpu {
+			lastCPUTimes = cpuTimes
+		} else {
+			lastPerCPUTimes = cpuTimes
+		}
+		time.Sleep(interval)
+		cpuTimes, err = CPUTimes(percpu)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	ret := make([]float32, len(cpuTimes))
+	if !percpu {
+		ret[0] = calculate(lastCPUTimes[0], cpuTimes[0])
+		lastCPUTimes = cpuTimes
+	} else {
+		for i, t := range cpuTimes {
+			ret[i] = calculate(lastPerCPUTimes[i], t)
+		}
+		lastPerCPUTimes = cpuTimes
+	}
+	return ret, nil
+}
+
 func (c CPUTimesStat) String() string {
 	s, _ := json.Marshal(c)
 	return string(s)
@@ -48,3 +100,8 @@ func (c CPUInfoStat) String() string {
 	s, _ := json.Marshal(c)
 	return string(s)
 }
+
+func init() {
+	lastCPUTimes, _ = CPUTimes(false)
+	lastPerCPUTimes, _ = CPUTimes(true)
+}

cpu_test.go

@@ -2,7 +2,9 @@ package gopsutil
 
 import (
 	"fmt"
+	"runtime"
 	"testing"
+	"time"
 )
 
 func TestCpu_times(t *testing.T) {
@@ -55,3 +57,33 @@ func TestCpuInfo(t *testing.T) {
 		}
 	}
 }
+
+func testCPUPercent(t *testing.T, percpu bool) {
+	v, err := CPUPercent(time.Millisecond, percpu)
+	if err != nil {
+		t.Errorf("error %v", err)
+	}
+	numcpu := runtime.NumCPU()
+	if (percpu && len(v) != numcpu) || (!percpu && len(v) != 1) {
+		t.Fatalf("wrong number of entries from CPUPercent: %v", v)
+	}
+	for i := 0; i < 1000; i++ {
+		v, err := CPUPercent(0, percpu)
+		if err != nil {
+			t.Errorf("error %v", err)
+		}
+		for _, percent := range v {
+			if percent < 0.0 || percent > 100.0*float32(numcpu) {
+				t.Fatalf("CPUPercent value is invalid: %f", percent)
+			}
+		}
+	}
+}
+
+func TestCPUPercent(t *testing.T) {
+	testCPUPercent(t, false)
+}
+
+func TestCPUPercentPerCpu(t *testing.T) {
+	testCPUPercent(t, true)
+}