Fix the way memory RSS is calculated for cgroupv2 (#40)

Author: treydock

collector/cgroupv2.go

@@ -171,7 +171,7 @@ func (e *Exporter) getMetricsv2(name string, pids []int, opts cgroup2.InitOpts)
 		return metric, err
 	}
 	if stats.Memory != nil {
-		metric.memoryRSS = float64(stats.Memory.Anon) + swapcached + float64(stats.Memory.AnonThp)
+		metric.memoryRSS = float64(stats.Memory.Anon) + swapcached + float64(stats.Memory.File)
 		metric.memoryUsed = float64(stats.Memory.Usage)
 		metric.memoryTotal = float64(stats.Memory.UsageLimit)
 		metric.memoryCache = float64(stats.Memory.File)

collector/cgroupv2_test.go

@@ -110,7 +110,7 @@ func TestCollectv2UserSlice(t *testing.T) {
 	if val := metrics[0].cpus; val != 0 {
 		t.Errorf("Unexpected value for cpus, got %v", val)
 	}
-	if val := metrics[0].memoryRSS; val != 22048768 {
+	if val := metrics[0].memoryRSS; val != 22626304 {
 		t.Errorf("Unexpected value for memoryRSS, got %v", val)
 	}
 	if val := metrics[0].memoryUsed; val != 27115520 {
@@ -184,7 +184,7 @@ func TestCollectv2SLURM(t *testing.T) {
 	if val := m.cpus; val != 1 {
 		t.Errorf("Unexpected value for cpus, got %v", val)
 	}
-	if val := m.memoryRSS; val != 2260992 {
+	if val := m.memoryRSS; val != 2777088 {
 		t.Errorf("Unexpected value for memoryRSS, got %v", val)
 	}
 	if val := m.memoryUsed; val != 5660672 {