Intel RDT: updates according to proposed spec changes.

libcontainer/intelrdt/intelrdt.go

@@ -146,10 +146,11 @@ import (
  */
 
 type Manager struct {
-	mu     sync.Mutex
-	config *configs.Config
-	id     string
-	path   string
+	mu               sync.Mutex
+	config           *configs.Config
+	id               string
+	path             string
+	directoryCreated bool
 }
 
 // NewManager returns a new instance of Manager, or nil if the Intel RDT
@@ -170,9 +171,10 @@ func NewManager(config *configs.Config, id string, path string) *Manager {
 // is actually available. Used by unit tests that mock intelrdt paths.
 func newManager(config *configs.Config, id string, path string) *Manager {
 	return &Manager{
-		config: config,
-		id:     id,
-		path:   path,
+		config:           config,
+		id:               id,
+		path:             path,
+		directoryCreated: false,
 	}
 }
 
@@ -466,6 +468,14 @@ func (m *Manager) Apply(pid int) (err error) {
 		}
 	}
 
+	// If the directory doesn't exist we need to create it -> it means we also need
+	// to clean it up afterwards. Make a note to the manager.
+	if _, err := os.Stat(path); err != nil {
+		if os.IsNotExist(err) {
+			m.directoryCreated = true
+		}
+	}
+
 	if err := os.MkdirAll(path, 0o755); err != nil {
 		return newLastCmdError(err)
 	}
@@ -482,8 +492,9 @@ func (m *Manager) Apply(pid int) (err error) {
 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 == "" {
+	// There are probably other containers/tasks sharing the same group. Also
+	// only remove the directory if it was created by us.
+	if m.config.IntelRdt != nil && m.config.IntelRdt.ClosID == "" && m.directoryCreated {
 		m.mu.Lock()
 		defer m.mu.Unlock()
 		if err := os.RemoveAll(m.GetPath()); err != nil {
@@ -589,6 +600,28 @@ func (m *Manager) GetStats() (*Stats, error) {
 	return stats, nil
 }
 
+func combineSchemas(l3CacheSchema, memBwSchema string) string {
+	// If both l3CacheSchema and memBwSchema are set and
+	// l3CacheSchema contains a line beginning with "MB:", the
+	// value written to schemata file MUST be the non-"MB:"
+	// line(s) from l3CacheSchema and the line from memBWSchema.
+
+	validLines := make([]string, 0)
+
+	// Split the l3CacheSchema to lines.
+	lines := strings.Split(l3CacheSchema, "\n")
+
+	// Remove the "MB:" lines.
+	for _, line := range lines {
+		if strings.HasPrefix(line, "MB:") {
+			continue
+		}
+		validLines = append(validLines, line)
+	}
+
+	return strings.Join(validLines, "\n") + "\n" + memBwSchema
+}
+
 // Set Intel RDT "resource control" filesystem as configured.
 func (m *Manager) Set(container *configs.Config) error {
 	// About L3 cache schema:
@@ -649,7 +682,8 @@ func (m *Manager) Set(container *configs.Config) error {
 
 		// Write a single joint schema string to schemata file
 		if l3CacheSchema != "" && memBwSchema != "" {
-			if err := writeFile(path, "schemata", l3CacheSchema+"\n"+memBwSchema); err != nil {
+			schemata := combineSchemas(l3CacheSchema, memBwSchema)
+			if err := writeFile(path, "schemata", schemata); err != nil {
 				return err
 			}
 		}

libcontainer/intelrdt/intelrdt_test.go

@@ -67,6 +67,46 @@ func TestIntelRdtSetMemBwSchema(t *testing.T) {
 	}
 }
 
+func TestIntelRdtSetCombinedSchema(t *testing.T) {
+	helper := NewIntelRdtTestUtil(t)
+
+	// Test filtering out the "MB:"" line in l3CacheSchema.
+
+	const (
+		schemaBefore        = "MB:0=20;1=70"
+		memBwSchema         = "MB:0=70;1=20"
+		l3CacheSchema       = "MB:0=80;1=10\nL3:0=f0;1=f"
+		combinedSchemaAfter = "L3:0=f0;1=f\nMB:0=70;1=20"
+	)
+
+	helper.writeFileContents(map[string]string{
+		"schemata": schemaBefore + "\n",
+	})
+
+	helper.config.IntelRdt.MemBwSchema = memBwSchema
+	helper.config.IntelRdt.L3CacheSchema = l3CacheSchema
+	intelrdt := newManager(helper.config, "", helper.IntelRdtPath)
+	if err := intelrdt.Set(helper.config); err != nil {
+		t.Fatal(err)
+	}
+
+	tmpStrings, err := getIntelRdtParamString(helper.IntelRdtPath, "schemata")
+	if err != nil {
+		t.Fatalf("Failed to parse file 'schemata' - %s", err)
+	}
+
+	readValues := strings.Split(tmpStrings, "\n")
+	expectedValues := strings.Split(combinedSchemaAfter, "\n")
+
+	if readValues[0] != expectedValues[0] {
+		t.Fatal("Got the wrong value for L3 cache, set 'schemata' failed.")
+	}
+
+	if readValues[1] != expectedValues[1] {
+		t.Fatal("Got the wrong value for MemBW, set 'schemata' failed.")
+	}
+}
+
 func TestIntelRdtSetMemBwScSchema(t *testing.T) {
 	helper := NewIntelRdtTestUtil(t)