libcontainer/intelrdt: add support for Schemata field

Implement support for the linux.intelRdt.schemata field of the spec.
This allows management of the "schemata" file in the resctrl group in a
generic way.

Signed-off-by: Markus Lehtonen <markus.lehtonen@intel.com>

features.go

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

libcontainer/configs/intelrdt.go

@@ -4,6 +4,10 @@ type IntelRdt struct {
 	// The identity for RDT Class of Service
 	ClosID string `json:"closID,omitempty"`
 
+	// Schemata is a generic field to specify schemata file in the resctrl
+	// filesystem. Each element represents one line written to the schemata file.
+	Schemata []string `json:"schemata,omitempty"`
+
 	// The schema for L3 cache id and capacity bitmask (CBM)
 	// Format: "L3:<cache_id0>=<cbm0>;<cache_id1>=<cbm1>;..."
 	L3CacheSchema string `json:"l3_cache_schema,omitempty"`

libcontainer/intelrdt/intelrdt.go

@@ -326,16 +326,6 @@ func getIntelRdtParamString(path, file string) (string, error) {
 	return string(bytes.TrimSpace(contents)), nil
 }
 
-func writeFile(dir, file, data string) error {
-	if dir == "" {
-		return fmt.Errorf("no such directory for %s", file)
-	}
-	if err := os.WriteFile(filepath.Join(dir, file), []byte(data+"\n"), 0o600); err != nil {
-		return newLastCmdError(fmt.Errorf("intelrdt: unable to write %v: %w", data, err))
-	}
-	return nil
-}
-
 // Get the read-only L3 cache information
 func getL3CacheInfo() (*L3CacheInfo, error) {
 	l3CacheInfo := &L3CacheInfo{}
@@ -462,11 +452,11 @@ func (m *Manager) Apply(pid int) (err error) {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
-	if m.config.IntelRdt.ClosID != "" && m.config.IntelRdt.L3CacheSchema == "" && m.config.IntelRdt.MemBwSchema == "" {
+	if m.config.IntelRdt.ClosID != "" && m.config.IntelRdt.L3CacheSchema == "" && m.config.IntelRdt.MemBwSchema == "" && len(m.config.IntelRdt.Schemata) == 0 {
 		// Check that the CLOS exists, i.e. it has been pre-configured to
 		// conform with the runtime spec
 		if _, err := os.Stat(path); err != nil {
-			return fmt.Errorf("clos dir not accessible (must be pre-created when l3CacheSchema and memBwSchema are empty): %w", err)
+			return fmt.Errorf("clos dir not accessible (must be pre-created when schemata, l3CacheSchema and memBwSchema are empty): %w", err)
 		}
 	}
 
@@ -637,35 +627,24 @@ func (m *Manager) Set(container *configs.Config) error {
 	// For example, on a two-socket machine, the schema line could be
 	// "MB:0=5000;1=7000" which means 5000 MBps memory bandwidth limit on
 	// socket 0 and 7000 MBps memory bandwidth limit on socket 1.
-	if container.IntelRdt != nil {
+	if r := container.IntelRdt; r != nil {
-		path := m.GetPath()
-		l3CacheSchema := container.IntelRdt.L3CacheSchema
-		memBwSchema := container.IntelRdt.MemBwSchema
-
 		// TODO: verify that l3CacheSchema and/or memBwSchema match the
 		// existing schemata if ClosID has been specified. This is a more
 		// involved than reading the file and doing plain string comparison as
 		// the value written in does not necessarily match what gets read out
 		// (leading zeros, cache id ordering etc).
-
+		var schemata strings.Builder
-		// Write a single joint schema string to schemata file
+		for _, s := range append([]string{r.L3CacheSchema, r.MemBwSchema}, r.Schemata...) {
-		if l3CacheSchema != "" && memBwSchema != "" {
+			if s != "" {
-			if err := writeFile(path, "schemata", l3CacheSchema+"\n"+memBwSchema); err != nil {
+				schemata.WriteString(s)
-				return err
+				schemata.WriteString("\n")
 			}
 		}
 
-		// Write only L3 cache schema string to schemata file
+		if schemata.Len() > 0 {
-		if l3CacheSchema != "" && memBwSchema == "" {
+			path := filepath.Join(m.GetPath(), "schemata")
-			if err := writeFile(path, "schemata", l3CacheSchema); err != nil {
+			if err := os.WriteFile(path, []byte(schemata.String()), 0o600); err != nil {
-				return err
+				return newLastCmdError(fmt.Errorf("intelrdt: unable to write %q: %w", schemata.String(), err))
-			}
-		}
-
-		// Write only memory bandwidth schema string to schemata file
-		if l3CacheSchema == "" && memBwSchema != "" {
-			if err := writeFile(path, "schemata", memBwSchema); err != nil {
-				return err
 			}
 		}
 	}

libcontainer/intelrdt/intelrdt_test.go

@@ -37,6 +37,69 @@ func TestIntelRdtSet(t *testing.T) {
 			},
 			schemataAfter: []string{"MB:0=9000;1=4000"},
 		},
+		{
+			name: "L3 and MemBw",
+			config: &configs.IntelRdt{
+				L3CacheSchema: "L3:0=f0;1=f",
+				MemBwSchema:   "MB:0=9000;1=4000",
+			},
+			schemataAfter: []string{
+				"L3:0=f0;1=f",
+				"MB:0=9000;1=4000",
+			},
+		},
+		{
+			name: "Schemata",
+			config: &configs.IntelRdt{
+				Schemata: []string{
+					"L3CODE:0=ff;1=ff",
+					"L3DATA:0=f;1=f0",
+				},
+			},
+			schemataAfter: []string{
+				"L3CODE:0=ff;1=ff",
+				"L3DATA:0=f;1=f0",
+			},
+		},
+		{
+			name: "Schemata and L3",
+			config: &configs.IntelRdt{
+				L3CacheSchema: "L3:0=f0;1=f",
+				Schemata:      []string{"L2:0=ff00;1=ff"},
+			},
+			schemataAfter: []string{
+				"L3:0=f0;1=f",
+				"L2:0=ff00;1=ff",
+			},
+		},
+		{
+			name: "Schemata and MemBw",
+			config: &configs.IntelRdt{
+				MemBwSchema: "MB:0=2000;1=4000",
+				Schemata:    []string{"L3:0=ff;1=ff"},
+			},
+			schemataAfter: []string{
+				"MB:0=2000;1=4000",
+				"L3:0=ff;1=ff",
+			},
+		},
+		{
+			name: "Schemata, L3 and MemBw",
+			config: &configs.IntelRdt{
+				L3CacheSchema: "L3:0=80;1=7f",
+				MemBwSchema:   "MB:0=2000;1=4000",
+				Schemata: []string{
+					"L2:0=ff00;1=ff",
+					"L3:0=c0;1=3f",
+				},
+			},
+			schemataAfter: []string{
+				"L3:0=80;1=7f",
+				"MB:0=2000;1=4000",
+				"L2:0=ff00;1=ff",
+				"L3:0=c0;1=3f",
+			},
+		},
 	}
 
 	for _, tc := range tcs {
@@ -44,11 +107,6 @@ func TestIntelRdtSet(t *testing.T) {
 			helper := NewIntelRdtTestUtil(t)
 			helper.config.IntelRdt = tc.config
 
-			helper.writeFileContents(map[string]string{
-				/* Common initial value for all test cases */
-				"schemata": "MB:0=100\nL3:0=ffff\nL2:0=ffffffff\n",
-			})
-
 			intelrdt := newManager(helper.config, "", helper.IntelRdtPath)
 			if err := intelrdt.Set(helper.config); err != nil {
 				t.Fatal(err)

libcontainer/intelrdt/util_test.go

@@ -40,13 +40,3 @@ func NewIntelRdtTestUtil(t *testing.T) *intelRdtTestUtil {
 	}
 	return &intelRdtTestUtil{config: config, IntelRdtPath: testIntelRdtPath, t: t}
 }
-
-// Write the specified contents on the mock of the specified Intel RDT "resource control" files
-func (c *intelRdtTestUtil) writeFileContents(fileContents map[string]string) {
-	for file, contents := range fileContents {
-		err := writeFile(c.IntelRdtPath, file, contents)
-		if err != nil {
-			c.t.Fatal(err)
-		}
-	}
-}

libcontainer/specconv/spec_linux.go

@@ -463,6 +463,7 @@ func CreateLibcontainerConfig(opts *CreateOpts) (*configs.Config, error) {
 		if spec.Linux.IntelRdt != nil {
 			config.IntelRdt = &configs.IntelRdt{
 				ClosID:        spec.Linux.IntelRdt.ClosID,
+				Schemata:      spec.Linux.IntelRdt.Schemata,
 				L3CacheSchema: spec.Linux.IntelRdt.L3CacheSchema,
 				MemBwSchema:   spec.Linux.IntelRdt.MemBwSchema,
 			}