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libct/intelrdt: use sync.OnceFunc and sync.OnceValues

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Switch from sync.Once to sync.OnceFunc and sync.OnceValues.

Keep Root a function (rather than a variable) because godoc
renders function doc better than a variable doc.

Switch to using internal function root internally.

Modify tests accordingly (and simplify NewIntelRdtTestUtil to
fakeRoot).

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
This commit is contained in:
Kir Kolyshkin
2026-04-23 11:33:06 -07:00
parent 2d2ae8809c
commit 16dde3befc
3 changed files with 83 additions and 106 deletions
Download Patch File Download Diff File Expand all files Collapse all files
libcontainer/intelrdt/intelrdt.go
+57 -71
View File
@@ -162,7 +162,7 @@ func NewManager(config *configs.Config, id, path string) *Manager {
return nil
}
rootPath, err := Root()
rootPath, err := root()
if err != nil {
return nil
}
@@ -197,47 +197,42 @@ var (
// The flag to indicate if Intel RDT/MBA is enabled
mbaEnabled bool
// For Intel RDT initialization
initOnce sync.Once
errNotFound = errors.New("Intel RDT not available")
)
// Check if Intel RDT sub-features are enabled in featuresInit()
func featuresInit() {
initOnce.Do(func() {
// 1. Check if Intel RDT "resource control" filesystem is available.
// The user guarantees to mount the filesystem.
root, err := Root()
if err != nil {
return
}
var featuresInit = sync.OnceFunc(func() {
// 1. Check if Intel RDT "resource control" filesystem is available.
// The user guarantees to mount the filesystem.
root, err := root()
if err != nil {
return
}
// 2. 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 _, err := os.Stat(filepath.Join(root, "info", "L3")); err == nil {
catEnabled = true
}
if _, err := os.Stat(filepath.Join(root, "info", "MB")); err == nil {
mbaEnabled = true
}
if _, err := os.Stat(filepath.Join(root, "info", "L3_MON")); err != nil {
return
}
enabledMonFeatures, err = getMonFeatures(root)
if err != nil {
return
}
if enabledMonFeatures.mbmTotalBytes || enabledMonFeatures.mbmLocalBytes {
mbmEnabled = true
}
if enabledMonFeatures.llcOccupancy {
cmtEnabled = true
}
})
}
// 2. 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 _, err := os.Stat(filepath.Join(root, "info", "L3")); err == nil {
catEnabled = true
}
if _, err := os.Stat(filepath.Join(root, "info", "MB")); err == nil {
mbaEnabled = true
}
if _, err := os.Stat(filepath.Join(root, "info", "L3_MON")); err != nil {
return
}
enabledMonFeatures, err = getMonFeatures(root)
if err != nil {
return
}
if enabledMonFeatures.mbmTotalBytes || enabledMonFeatures.mbmLocalBytes {
mbmEnabled = true
}
if enabledMonFeatures.llcOccupancy {
cmtEnabled = true
}
})
// findIntelRdtMountpointDir returns the mount point of the Intel RDT "resource control" filesystem.
func findIntelRdtMountpointDir() (string, error) {
@@ -258,13 +253,6 @@ func findIntelRdtMountpointDir() (string, error) {
return mi[0].Mountpoint, nil
}
// For Root() use only.
var (
intelRdtRoot string
intelRdtRootErr error
rootOnce sync.Once
)
// The kernel creates this (empty) directory if resctrl is supported by the
// hardware and kernel. The user is responsible for mounting the resctrl
// filesystem, and they could mount it somewhere else if they wanted to.
@@ -272,30 +260,28 @@ const defaultResctrlMountpoint = "/sys/fs/resctrl"
// Root returns the Intel RDT "resource control" filesystem mount point.
func Root() (string, error) {
rootOnce.Do(func() {
// Does this system support resctrl?
var statfs unix.Statfs_t
if err := unix.Statfs(defaultResctrlMountpoint, &statfs); err != nil {
if errors.Is(err, unix.ENOENT) {
err = errNotFound
}
intelRdtRootErr = err
return
}
// Has the resctrl fs been mounted to the default mount point?
if statfs.Type == unix.RDTGROUP_SUPER_MAGIC {
intelRdtRoot = defaultResctrlMountpoint
return
}
// The resctrl fs could have been mounted somewhere nonstandard.
intelRdtRoot, intelRdtRootErr = findIntelRdtMountpointDir()
})
return intelRdtRoot, intelRdtRootErr
return root()
}
var root = sync.OnceValues(func() (string, error) {
// Does this system support resctrl?
var statfs unix.Statfs_t
if err := unix.Statfs(defaultResctrlMountpoint, &statfs); err != nil {
if errors.Is(err, unix.ENOENT) {
err = errNotFound
}
return "", err
}
// Has the resctrl fs been mounted to the default mount point?
if statfs.Type == unix.RDTGROUP_SUPER_MAGIC {
return defaultResctrlMountpoint, nil
}
// The resctrl fs could have been mounted somewhere nonstandard.
return findIntelRdtMountpointDir()
})
// Gets a single uint64 value from the specified file.
func getIntelRdtParamUint(path, file string) (uint64, error) {
fileName := filepath.Join(path, file)
@@ -325,7 +311,7 @@ func getIntelRdtParamString(path, file string) (string, error) {
func getL3CacheInfo() (*L3CacheInfo, error) {
l3CacheInfo := &L3CacheInfo{}
rootPath, err := Root()
rootPath, err := root()
if err != nil {
return l3CacheInfo, err
}
@@ -355,7 +341,7 @@ func getL3CacheInfo() (*L3CacheInfo, error) {
func getMemBwInfo() (*MemBwInfo, error) {
memBwInfo := &MemBwInfo{}
rootPath, err := Root()
rootPath, err := root()
if err != nil {
return memBwInfo, err
}
@@ -388,7 +374,7 @@ func getMemBwInfo() (*MemBwInfo, error) {
// Get diagnostics for last filesystem operation error from file info/last_cmd_status
func getLastCmdStatus() (string, error) {
rootPath, err := Root()
rootPath, err := root()
if err != nil {
return "", err
}
@@ -419,7 +405,7 @@ func WriteIntelRdtTasks(dir string, pid int) error {
// IsEnabled checks if Intel RDT is enabled.
func IsEnabled() bool {
fsroot, err := Root()
fsroot, err := root()
return err == nil && fsroot != ""
}
@@ -538,7 +524,7 @@ func (m *Manager) GetStats() (*Stats, error) {
defer m.mu.Unlock()
stats := newStats()
rootPath, err := Root()
rootPath, err := root()
if err != nil {
return nil, err
}
libcontainer/intelrdt/intelrdt_test.go
+10 -9
View File
@@ -105,18 +105,20 @@ func TestIntelRdtSet(t *testing.T) {
for _, tc := range tcs {
t.Run(tc.name, func(t *testing.T) {
helper := NewIntelRdtTestUtil(t)
helper.config.IntelRdt = tc.config
intelRdtRoot := fakeRoot(t)
config := &configs.Config{
IntelRdt: tc.config,
}
intelrdt := &Manager{
config: helper.config,
path: helper.IntelRdtPath,
config: config,
path: intelRdtRoot,
}
if err := intelrdt.Set(helper.config); err != nil {
if err := intelrdt.Set(config); err != nil {
t.Fatal(err)
}
tmpStrings, err := getIntelRdtParamString(helper.IntelRdtPath, "schemata")
tmpStrings, err := getIntelRdtParamString(intelRdtRoot, "schemata")
if err != nil {
t.Fatalf("Failed to parse file 'schemata' - %s", err)
}
@@ -186,7 +188,7 @@ func TestApply(t *testing.T) {
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
NewIntelRdtTestUtil(t)
intelRdtRoot := fakeRoot(t)
id := "abcd-1234"
closPath := filepath.Join(intelRdtRoot, id)
if tt.config.ClosID != "" {
@@ -288,8 +290,7 @@ func TestDestroy(t *testing.T) {
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
NewIntelRdtTestUtil(t)
intelRdtRoot := fakeRoot(t)
id := "abcd-1234"
closPath := filepath.Join(intelRdtRoot, id)
if tt.config.ClosID != "" {
libcontainer/intelrdt/util_test.go
+16 -26
View File
@@ -8,35 +8,25 @@ import (
"os"
"path/filepath"
"testing"
"github.com/opencontainers/runc/libcontainer/configs"
)
type intelRdtTestUtil struct {
config *configs.Config
// Path to the mock Intel RDT "resource control" filesystem directory
IntelRdtPath string
t *testing.T
}
// Creates a new test util
func NewIntelRdtTestUtil(t *testing.T) *intelRdtTestUtil {
config := &configs.Config{
IntelRdt: &configs.IntelRdt{},
}
// fakeRoot creates a new fake root for tests and returns its path.
// Once this is called, Root() returns the same path.
func fakeRoot(t *testing.T) string {
// Assign fake intelRtdRoot value, returned by Root().
intelRdtRoot = t.TempDir()
// Make sure Root() won't even try to parse mountinfo.
rootOnce.Do(func() {})
testIntelRdtPath := filepath.Join(intelRdtRoot, "resctrl")
// Ensure the full mock Intel RDT "resource control" filesystem path exists
if err := os.MkdirAll(testIntelRdtPath, 0o755); err != nil {
intelRdtRoot := filepath.Join(t.TempDir(), "resctrl")
if err := os.MkdirAll(intelRdtRoot, 0o755); err != nil {
t.Fatal(err)
}
return &intelRdtTestUtil{config: config, IntelRdtPath: testIntelRdtPath, t: t}
origRoot := root
t.Cleanup(func() {
root = origRoot
})
root = func() (string, error) {
return intelRdtRoot, nil
}
return intelRdtRoot
}