sysfs: survive NUMA nodes without memory.

Don't fail for CPU-only NUMA nodes. Treat them as DRAM nodes with 0
bytes of memory attached, but exclude them when calculating average
memory size for memory type approximation.

Signed-off-by: Krisztian Litkey <[email protected]>

pkg/sysfs/system.go

@@ -1183,6 +1183,15 @@ func (sys *system) discoverNodes() error {
 		return fmt.Errorf("failed to parse nodes with memory (%q): %v",
 			memoryNodeIDs, err)
 	}
+	onlineNodeIDs, err := readSysfsEntry(sysNodesPath, "online", nil)
+	if err != nil {
+		return fmt.Errorf("failed to discover online nodes: %v", err)
+	}
+	onlineNodes, err := cpuset.Parse(onlineNodeIDs)
+	if err != nil {
+		return fmt.Errorf("failed to parse online nodes (%q): %v",
+			onlineNodeIDs, err)
+	}
 
 	cpuNodesSlice := []int{}
 	for id, node := range sys.nodes {
@@ -1199,7 +1208,8 @@ func (sys *system) discoverNodes() error {
 	sys.Logger.Info("NUMA nodes with (any) memory: %s", memoryNodes.String())
 	sys.Logger.Info("NUMA nodes with normal memory: %s", normalMemNodes.String())
 
-	dramNodes := memoryNodes.Intersection(cpuNodes)
+	noMemNodes := onlineNodes.Difference(memoryNodes)
+	dramNodes := memoryNodes.Intersection(cpuNodes).Union(noMemNodes)
 	pmemOrHbmNodes := memoryNodes.Difference(dramNodes)
 
 	dramNodeIds := IDSetFromCPUSet(dramNodes)
@@ -1224,7 +1234,7 @@ func (sys *system) discoverNodes() error {
 				dramTotal += info.MemTotal
 			}
 		}
-		dramAvg = dramTotal / uint64(len(dramNodeIds))
+		dramAvg = dramTotal / uint64(len(dramNodeIds)-noMemNodes.Size())
 		if dramAvg == 0 {
 			// FIXME: should be no reason to bail out when memory types are properly determined.
 			return fmt.Errorf("no dram in the system, cannot determine special memory types")