libcontainer/intelrdt: rm init() from intelrdt.go

Use sync.Once to init Intel RDT when needed for a small speedup to
operations which do not require Intel RDT.

Simplify IntelRdtManager initialization in LinuxFactory.

Signed-off-by: Xiaochen Shen <[email protected]>

Author: xiaochenshen

libcontainer/factory_linux.go

@@ -148,8 +148,13 @@ func RootlessCgroupfs(l *LinuxFactory) error {
 // containers that use the Intel RDT "resource control" filesystem to
 // create and manage Intel RDT resources (e.g., L3 cache, memory bandwidth).
 func IntelRdtFs(l *LinuxFactory) error {
-	l.NewIntelRdtManager = func(config *configs.Config, id string, path string) intelrdt.Manager {
-		return intelrdt.NewManager(config, id, path)
+	intelrdt.InitIntelRdt()
+	if !intelrdt.IsCATEnabled() && !intelrdt.IsMBAEnabled() {
+		l.NewIntelRdtManager = nil
+	} else {
+		l.NewIntelRdtManager = func(config *configs.Config, id string, path string) intelrdt.Manager {
+			return intelrdt.NewManager(config, id, path)
+		}
 	}
 	return nil
 }
@@ -272,7 +277,7 @@ func (l *LinuxFactory) Create(id string, config *configs.Config) (Container, err
 		newgidmapPath: l.NewgidmapPath,
 		cgroupManager: l.NewCgroupsManager(config.Cgroups, nil),
 	}
-	if intelrdt.IsCATEnabled() || intelrdt.IsMBAEnabled() {
+	if l.NewIntelRdtManager != nil {
 		c.intelRdtManager = l.NewIntelRdtManager(config, id, "")
 	}
 	c.state = &stoppedState{c: c}
@@ -314,13 +319,13 @@ func (l *LinuxFactory) Load(id string) (Container, error) {
 		root:                 containerRoot,
 		created:              state.Created,
 	}
+	if l.NewIntelRdtManager != nil {
+		c.intelRdtManager = l.NewIntelRdtManager(&state.Config, id, state.IntelRdtPath)
+	}
 	c.state = &loadedState{c: c}
 	if err := c.refreshState(); err != nil {
 		return nil, err
 	}
-	if intelrdt.IsCATEnabled() || intelrdt.IsMBAEnabled() {
-		c.intelRdtManager = l.NewIntelRdtManager(&state.Config, id, state.IntelRdtPath)
-	}
 	return c, nil
 }
 

libcontainer/intelrdt/intelrdt.go

@@ -195,6 +195,9 @@ var (
 	mbaEnabled bool
 	// The flag to indicate if Intel RDT/MBA Software Controller is enabled
 	mbaScEnabled bool
+
+	// For Intel RDT initialization
+	initOnce sync.Once
 )
 
 type intelRdtData struct {
@@ -203,55 +206,56 @@ type intelRdtData struct {
 	pid    int
 }
 
-// Check if Intel RDT sub-features are enabled in init()
-func init() {
-	// 1. Check if hardware and kernel support Intel RDT sub-features
-	flagsSet, err := parseCpuInfoFile("/proc/cpuinfo")
-	if err != nil {
-		return
-	}
-
-	// 2. Check if Intel RDT "resource control" filesystem is mounted
-	// The user guarantees to mount the filesystem
-	if !isIntelRdtMounted() {
-		return
-	}
-
-	// 3. Double check if Intel RDT sub-features are available in
-	// "resource control" filesystem. Intel RDT sub-features can be
-	// selectively disabled or enabled by kernel command line
-	// (e.g., rdt=!l3cat,mba) in 4.14 and newer kernel
-	if flagsSet.CAT {
-		if _, err := os.Stat(filepath.Join(intelRdtRoot, "info", "L3")); err == nil {
-			catEnabled = true
-		}
-	}
-	if mbaScEnabled {
-		// We confirm MBA Software Controller is enabled in step 2,
-		// MBA should be enabled because MBA Software Controller
-		// depends on MBA
-		mbaEnabled = true
-	} else if flagsSet.MBA {
-		if _, err := os.Stat(filepath.Join(intelRdtRoot, "info", "MB")); err == nil {
-			mbaEnabled = true
+// Check if Intel RDT sub-features are enabled in InitIntelRdt()
+func InitIntelRdt() {
+	initOnce.Do(func() {
+		// 1. Check if hardware and kernel support Intel RDT sub-features
+		flagsSet, err := parseCpuInfoFile("/proc/cpuinfo")
+		if err != nil {
+			return
 		}
-	}
 
-	if flagsSet.MBMTotal || flagsSet.MBMLocal || flagsSet.CMT {
-		if _, err := os.Stat(filepath.Join(intelRdtRoot, "info", "L3_MON")); err != nil {
+		// 2. Check if Intel RDT "resource control" filesystem is mounted
+		// The user guarantees to mount the filesystem
+		if !isIntelRdtMounted() {
 			return
 		}
-		enabledMonFeatures, err = getMonFeatures(intelRdtRoot)
-		if err != nil {
-			return
+
+		// 3. Double check if Intel RDT sub-features are available in
+		// "resource control" filesystem. Intel RDT sub-features can be
+		// selectively disabled or enabled by kernel command line
+		// (e.g., rdt=!l3cat,mba) in 4.14 and newer kernel
+		if flagsSet.CAT {
+			if _, err := os.Stat(filepath.Join(intelRdtRoot, "info", "L3")); err == nil {
+				catEnabled = true
+			}
 		}
-		if enabledMonFeatures.mbmTotalBytes || enabledMonFeatures.mbmLocalBytes {
-			mbmEnabled = true
+		if mbaScEnabled {
+			// We confirm MBA Software Controller is enabled in step 2,
+			// MBA should be enabled because MBA Software Controller
+			// depends on MBA
+			mbaEnabled = true
+		} else if flagsSet.MBA {
+			if _, err := os.Stat(filepath.Join(intelRdtRoot, "info", "MB")); err == nil {
+				mbaEnabled = true
+			}
 		}
-		if enabledMonFeatures.llcOccupancy {
-			cmtEnabled = true
+		if flagsSet.MBMTotal || flagsSet.MBMLocal || flagsSet.CMT {
+			if _, err := os.Stat(filepath.Join(intelRdtRoot, "info", "L3_MON")); err != nil {
+				return
+			}
+			enabledMonFeatures, err = getMonFeatures(intelRdtRoot)
+			if err != nil {
+				return
+			}
+			if enabledMonFeatures.mbmTotalBytes || enabledMonFeatures.mbmLocalBytes {
+				mbmEnabled = true
+			}
+			if enabledMonFeatures.llcOccupancy {
+				cmtEnabled = true
+			}
 		}
-	}
+	})
 }
 
 // Return the mount point path of Intel RDT "resource control" filesysem

utils_linux.go

@@ -13,7 +13,6 @@ import (
 	"github.com/opencontainers/runc/libcontainer"
 	"github.com/opencontainers/runc/libcontainer/cgroups/systemd"
 	"github.com/opencontainers/runc/libcontainer/configs"
-	"github.com/opencontainers/runc/libcontainer/intelrdt"
 	"github.com/opencontainers/runc/libcontainer/specconv"
 	"github.com/opencontainers/runc/libcontainer/utils"
 	"github.com/opencontainers/runtime-spec/specs-go"
@@ -57,9 +56,6 @@ func loadFactory(context *cli.Context) (libcontainer.Factory, error) {
 	}
 
 	intelRdtManager := libcontainer.IntelRdtFs
-	if !intelrdt.IsCATEnabled() && !intelrdt.IsMBAEnabled() {
-		intelRdtManager = nil
-	}
 
 	// We resolve the paths for {newuidmap,newgidmap} from the context of runc,
 	// to avoid doing a path lookup in the nsexec context. TODO: The binary