Add swap support in nfd

deployment/components/common/worker-mounts.yaml

@@ -4,6 +4,9 @@
   - name: host-boot
     hostPath:
       path: "/boot"
+  - name: host-proc-swaps
+    hostPath:
+      path: "/proc/swaps"
   - name: host-os-release
     hostPath:
       path: "/etc/os-release"
@@ -38,6 +41,9 @@
   - name: host-sys
     mountPath: "/host-sys"
     readOnly: true
+  - name: host-proc-swaps
+    mountPath: "/host-swaps"
+    readOnly: true
   - name: host-usr-lib
     mountPath: "/host-usr/lib"
     readOnly: true

deployment/helm/node-feature-discovery/templates/worker.yaml

@@ -87,6 +87,9 @@ spec:
         - name: host-lib
           mountPath: "/host-lib"
           readOnly: true
+        - name: host-proc-swaps
+W2AQ          mountPath: "/host-proc/swaps"
+          readOnly: true
         {{- if .Values.worker.mountUsrSrc }}
         - name: host-usr-src
           mountPath: "/host-usr/src"
@@ -122,6 +125,9 @@ spec:
         - name: host-lib
           hostPath:
             path: "/lib"
+        - name: host-proc/swaps
+          hostPath:
+            path: "/proc/swaps"
         {{- if .Values.worker.mountUsrSrc }}
         - name: host-usr-src
           hostPath:

docs/usage/customization-guide.md

@@ -966,6 +966,8 @@ The following features are available for matching:
 | **`memory.numa`**  | attribute  |          |            | NUMA nodes |
 |                  |              | **`is_numa`** | bool  | `true` if NUMA architecture, `false` otherwise |
 |                  |              | **`node_count`** | int | Number of NUMA nodes |
+| **`memory.swap`**  | attribute  |          |            | Swap enabled on node |
+|                  |              | **`enabled`** | bool  | `true` if swap partition detected, `false` otherwise |
 | **`network.device`** | instance |          |            | Physical (non-virtual) network interfaces present in the system |
 |                  |              | **`name`** | string   | Name of the network interface |
 |                  |              | **`<sysfs-attribute>`** | string | Sysfs network interface attribute, available attributes: `operstate`, `speed`, `sriov_numvfs`, `sriov_totalvfs` |

docs/usage/features.md

@@ -177,6 +177,7 @@ configuration options for details.
 | **`memory-numa`**    | true  | Multiple memory nodes i.e. NUMA architecture detected     |
 | **`memory-nv.present`** | true | NVDIMM device(s) are present                              |
 | **`memory-nv.dax`** | true  | NVDIMM region(s) configured in DAX mode are present        |
+| **`memory-swap.enabled`** | true  | Swap is enabled on the node                          |
 
 ### Network
 

pkg/utils/hostpath/hostpath.go

@@ -34,6 +34,8 @@ var (
 	VarDir = HostDir(pathPrefix + "var")
 	// LibDir is where the /lib directory of the system to be inspected is located
 	LibDir = HostDir(pathPrefix + "lib")
+	// ProcDir is where the /proc directory of the system to be inspected is located
+	ProcDir = HostDir(pathPrefix + "proc")
 )
 
 // HostDir is a helper for handling host system directories

source/memory/memory.go

@@ -40,6 +40,9 @@ const NvFeature = "nv"
 // NumaFeature is the name of the feature set that holds all NUMA related features.
 const NumaFeature = "numa"
 
+// SwapFeature is the name of the feature set that holds all Swap related features
+const SwapFeature = "swap"
+
 // memorySource implements the FeatureSource and LabelSource interfaces.
 type memorySource struct {
 	features *nfdv1alpha1.Features
@@ -68,6 +71,11 @@ func (s *memorySource) GetLabels() (source.FeatureLabels, error) {
 		labels["numa"] = true
 	}
 
+	// Swap
+	if isSwap, ok := features.Attributes[SwapFeature].Elements["enabled"]; ok && isSwap == "true" {
+		labels["swap"] = true
+	}
+
 	// NVDIMM
 	if len(features.Instances[NvFeature].Elements) > 0 {
 		labels["nv.present"] = true
@@ -93,6 +101,13 @@ func (s *memorySource) Discover() error {
 		s.features.Attributes[NumaFeature] = nfdv1alpha1.AttributeFeatureSet{Elements: numa}
 	}
 
+	// Detect Swap
+	if swap, err := detectSwap(); err != nil {
+		klog.ErrorS(err, "failed to detect Swap nodes")
+	} else {
+		s.features.Attributes[SwapFeature] = nfdv1alpha1.AttributeFeatureSet{Elements: swap}
+	}
+
 	// Detect NVDIMM
 	if nv, err := detectNv(); err != nil {
 		klog.ErrorS(err, "failed to detect nvdimm devices")
@@ -113,6 +128,20 @@ func (s *memorySource) GetFeatures() *nfdv1alpha1.Features {
 	return s.features
 }
 
+// detectSwap detects Swap node information
+func detectSwap() (map[string]string, error) {
+	procBasePath := hostpath.ProcDir.Path("swaps")
+	lines, err := getNumberOfLinesFromFile(procBasePath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read swaps file: %w", err)
+	}
+	// /proc/swaps has a header row
+	// If there is more than a header then we assume we have swap.
+	return map[string]string{
+		"enabled": strconv.FormatBool(lines > 1),
+	}, nil
+}
+
 // detectNuma detects NUMA node information
 func detectNuma() (map[string]string, error) {
 	sysfsBasePath := hostpath.SysfsDir.Path("bus/node/devices")
@@ -166,6 +195,14 @@ func readNdDeviceInfo(path string) nfdv1alpha1.InstanceFeature {
 	return *nfdv1alpha1.NewInstanceFeature(attrs)
 }
 
+func getNumberOfLinesFromFile(path string) (int, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return 0, err
+	}
+	return len(strings.Split(string(data), "\n")), nil
+}
+
 func init() {
 	source.Register(&src)
 }

source/memory/memory_test.go

@@ -31,5 +31,33 @@ func TestMemorySource(t *testing.T) {
 
 	assert.Nil(t, err, err)
 	assert.Empty(t, l)
+}
 
+func TestGetNumberofLinesFromFile(t *testing.T) {
+	type testCase struct {
+		path          string
+		expectedLines int
+		expectErr     bool
+	}
+	tc := []testCase{
+		{
+			path:          "testdata/swap",
+			expectedLines: 2,
+		},
+		{
+			path:          "testdata/noswap",
+			expectedLines: 1,
+		},
+		{
+			path:      "file_not_exist",
+			expectErr: true,
+		},
+	}
+	for _, tc := range tc {
+		actual, err := getNumberOfLinesFromFile(tc.path)
+		if tc.expectErr {
+			assert.NotNil(t, err, "should get an error")
+		}
+		assert.Equal(t, tc.expectedLines, actual, "lines should match")
+	}
 }

source/memory/testdata/noswap

@@ -0,0 +1 @@
+Filename                          Type        Size     Used    Priority

source/memory/testdata/swap

@@ -0,0 +1,2 @@
+Filename                          Type        Size     Used    Priority
+dummyfile   partition   65555   0       -1