libcontainer/intelrdt: add support for EnableMonitoring field

The linux.intelRdt.enableMonitoring field enables the creation of
a per-container monitoring group. The monitoring group is removed when
the container is destroyed.

Signed-off-by: Markus Lehtonen <[email protected]>

Author: marquiz

features.go

@@ -56,7 +56,8 @@ var featuresCommand = cli.Command{
 					Enabled: &t,
 				},
 				IntelRdt: &features.IntelRdt{
-					Enabled: &t,
+					Enabled:    &t,
+					Monitoring: &t,
 				},
 				MountExtensions: &features.MountExtensions{
 					IDMap: &features.IDMap{

libcontainer/configs/intelrdt.go

@@ -13,4 +13,7 @@ type IntelRdt struct {
 	// The unit of memory bandwidth is specified in "percentages" by
 	// default, and in "MBps" if MBA Software Controller is enabled.
 	MemBwSchema string `json:"memBwSchema,omitempty"`
+
+	// Create a monitoring group for the container.
+	EnableMonitoring bool `json:"enableMonitoring,omitempty"`
 }

libcontainer/configs/validate/intelrdt_test.go

@@ -19,30 +19,24 @@ func TestValidateIntelRdt(t *testing.T) {
 		isErr      bool
 	}{
 		{
-			name:       "rdt not supported, no config",
-			rdtEnabled: false,
-			config:     nil,
-			isErr:      false,
+			name: "rdt not supported, no config",
 		},
 		{
-			name:       "rdt not supported, with config",
-			rdtEnabled: false,
-			config:     &configs.IntelRdt{},
-			isErr:      true,
+			name:   "rdt not supported, with config",
+			config: &configs.IntelRdt{},
+			isErr:  true,
 		},
 		{
 			name:       "empty config",
 			rdtEnabled: true,
 			config:     &configs.IntelRdt{},
-			isErr:      false,
 		},
 		{
 			name:       "root clos",
 			rdtEnabled: true,
 			config: &configs.IntelRdt{
 				ClosID: "/",
 			},
-			isErr: false,
 		},
 		{
 			name:       "invalid ClosID (.)",
@@ -71,7 +65,6 @@ func TestValidateIntelRdt(t *testing.T) {
 		{
 			name:       "cat not supported",
 			rdtEnabled: true,
-			catEnabled: false,
 			config: &configs.IntelRdt{
 				L3CacheSchema: "0=ff",
 			},
@@ -80,7 +73,6 @@ func TestValidateIntelRdt(t *testing.T) {
 		{
 			name:       "mba not supported",
 			rdtEnabled: true,
-			mbaEnabled: false,
 			config: &configs.IntelRdt{
 				MemBwSchema: "0=100",
 			},
@@ -96,7 +88,6 @@ func TestValidateIntelRdt(t *testing.T) {
 				L3CacheSchema: "0=ff",
 				MemBwSchema:   "0=100",
 			},
-			isErr: false,
 		},
 	}
 	for _, tc := range testCases {

libcontainer/container_linux.go

@@ -73,6 +73,11 @@ type State struct {
 
 	// Intel RDT "resource control" filesystem path.
 	IntelRdtPath string `json:"intel_rdt_path,omitempty"`
+
+	// Path of the container specific monitoring group in resctrl filesystem.
+	// Empty if the container does not have aindividual dedicated monitoring
+	// group.
+	IntelRdtMonPath string `json:"intel_rdt_mon_path,omitempty"`
 }
 
 // ID returns the container's unique ID
@@ -938,8 +943,10 @@ func (c *Container) currentState() *State {
 	}
 
 	intelRdtPath := ""
+	intelRdtMonPath := ""
 	if c.intelRdtManager != nil {
 		intelRdtPath = c.intelRdtManager.GetPath()
+		intelRdtMonPath = c.intelRdtManager.GetMonPath()
 	}
 	state := &State{
 		BaseState: BaseState{
@@ -952,6 +959,7 @@ func (c *Container) currentState() *State {
 		Rootless:            c.config.RootlessEUID && c.config.RootlessCgroups,
 		CgroupPaths:         c.cgroupManager.GetPaths(),
 		IntelRdtPath:        intelRdtPath,
+		IntelRdtMonPath:     intelRdtMonPath,
 		NamespacePaths:      make(map[configs.NamespaceType]string),
 		ExternalDescriptors: externalDescriptors,
 	}

libcontainer/intelrdt/intelrdt.go

@@ -478,6 +478,16 @@ func (m *Manager) Apply(pid int) (err error) {
 		return newLastCmdError(err)
 	}
 
+	// Create MON group
+	if monPath := m.GetMonPath(); monPath != "" {
+		if err := os.Mkdir(monPath, 0o755); err != nil && !os.IsExist(err) {
+			return newLastCmdError(err)
+		}
+		if err := WriteIntelRdtTasks(monPath, pid); err != nil {
+			return newLastCmdError(err)
+		}
+	}
+
 	m.path = path
 	return nil
 }
@@ -487,13 +497,21 @@ func (m *Manager) Destroy() error {
 	// Don't remove resctrl group if closid has been explicitly specified. The
 	// group is likely externally managed, i.e. by some other entity than us.
 	// There are probably other containers/tasks sharing the same group.
-	if m.config.IntelRdt != nil && m.config.IntelRdt.ClosID == "" {
-		m.mu.Lock()
-		defer m.mu.Unlock()
-		if err := os.Remove(m.GetPath()); err != nil && !os.IsNotExist(err) {
-			return err
+	if m.config.IntelRdt != nil {
+		if m.config.IntelRdt.ClosID == "" {
+			m.mu.Lock()
+			defer m.mu.Unlock()
+			if err := os.Remove(m.GetPath()); err != nil && !os.IsNotExist(err) {
+				return err
+			}
+			m.path = ""
+		} else if monPath := m.GetMonPath(); monPath != "" {
+			// If ClosID is not specified the possible monintoring group was
+			// removed with the CLOS above.
+			if err := os.Remove(monPath); err != nil && !os.IsNotExist(err) {
+				return err
+			}
 		}
-		m.path = ""
 	}
 	return nil
 }
@@ -504,6 +522,21 @@ func (m *Manager) GetPath() string {
 	return m.path
 }
 
+// GetMonPath returns path of the monitoring group of the container. Returns an
+// empty string if the container does not have a individual dedicated
+// monitoring group.
+func (m *Manager) GetMonPath() string {
+	if !m.config.IntelRdt.EnableMonitoring {
+		return ""
+	}
+	closPath := m.GetPath()
+	if closPath == "" {
+		return ""
+	}
+
+	return filepath.Join(closPath, "mon_groups", m.id)
+}
+
 // GetStats returns statistics for Intel RDT.
 func (m *Manager) GetStats() (*Stats, error) {
 	// If intelRdt is not specified in config
@@ -581,7 +614,16 @@ func (m *Manager) GetStats() (*Stats, error) {
 	}
 
 	if IsMBMEnabled() || IsCMTEnabled() {
-		err = getMonitoringStats(containerPath, stats)
+		monPath := m.GetMonPath()
+		if monPath == "" {
+			// NOTE: If per-container monitoring is not enabled, the monitoring
+			// data we get here might have little to do with this container as
+			// there might be anything from this single container to the half
+			// of the system assigned in the group. Should consider not
+			// exposing stats in this case(?)
+			monPath = containerPath
+		}
+		err = getMonitoringStats(monPath, stats)
 		if err != nil {
 			return nil, err
 		}