agent: Change monitor queue size default

The existing default of 0.5M entries for the buffered go channel wastes a lot
of of memory in smaller environments. Reduce it to 32K and allow to customize
it for bigger environments via --monitor-queue-size=INT

Signed-off-by: Thomas Graf <thomas@cilium.io>

Documentation/cmdref/cilium-agent.md

@@ -78,6 +78,7 @@ cilium-agent
       --logstash-probe-timer uint32                 Logstash probe timer (seconds) (default 10)
       --masquerade                                  Masquerade packets from endpoints leaving the host (default true)
       --monitor-aggregation string                  Level of monitor aggregation for traces from the datapath (default "None")
+      --monitor-queue-size int                      Size of the event queue when reading monitor events (default 32768)
       --mtu int                                     Overwrite auto-detected MTU of underlying network (default 1500)
       --nat46-range string                          IPv6 prefix to map IPv4 addresses to (default "0:0:0:0:0:FFFF::/96")
       --pprof                                       Enable serving the pprof debugging API

daemon/config.go

@@ -49,4 +49,5 @@ func populateConfig() {
 	option.Config.K8sNamespace = viper.GetString(option.K8sNamespaceName)
 	option.Config.EnableIPv4 = getIPv4Enabled()
 	option.Config.EnableIPv6 = viper.GetBool(option.EnableIPv6Name)
+	option.Config.MonitorQueueSize = viper.GetInt(option.MonitorQueueSizeName)
 }

daemon/daemon.go

@@ -859,7 +859,7 @@ func NewDaemon() (*Daemon, *endpointRestoreState, error) {
 		k8sSvcCache:   k8s.NewServiceCache(),
 		policy:        policy.NewPolicyRepository(),
 		uniqueID:      map[uint64]context.CancelFunc{},
-		nodeMonitor:   monitorLaunch.NewNodeMonitor(),
+		nodeMonitor:   monitorLaunch.NewNodeMonitor(option.Config.MonitorQueueSize),
 		prefixLengths: createPrefixLengthCounter(),
 
 		buildEndpointSem: semaphore.NewWeighted(int64(numWorkerThreads())),

daemon/daemon_main.go

@@ -474,6 +474,9 @@ func init() {
 	flags.String(option.MonitorAggregationName, "None",
 		"Level of monitor aggregation for traces from the datapath")
 	viper.BindEnv(option.MonitorAggregationName, "CILIUM_MONITOR_AGGREGATION_LEVEL")
+	flags.Int(option.MonitorQueueSizeName, defaults.MonitorQueueSize,
+		"Size of the event queue when reading monitor events")
+	viper.BindEnv(option.MonitorQueueSizeName, option.MonitorQueueSizeNameEnv)
 	flags.IntVar(&option.Config.MTU,
 		option.MTUName, mtu.AutoDetect(), "Overwrite auto-detected MTU of underlying network")
 	flags.Bool(option.PrependIptablesChainsName, true, "Prepend custom iptables chains instead of appending")

monitor/launch/launcher.go

@@ -38,9 +38,6 @@ var log = logging.DefaultLogger.WithField(logfields.LogSubsys, "monitor-launcher
 
 const (
 	targetName = "cilium-node-monitor"
-
-	// queueSize is the size of the message queue
-	queueSize = 524288
 )
 
 // NodeMonitor is used to wrap the node executable binary.
@@ -59,7 +56,7 @@ type NodeMonitor struct {
 }
 
 // NewNodeMonitor returns a new node monitor
-func NewNodeMonitor() *NodeMonitor {
+func NewNodeMonitor(queueSize int) *NodeMonitor {
 	nm := &NodeMonitor{
 		queue: make(chan []byte, queueSize),
 	}

pkg/defaults/defaults.go

@@ -114,4 +114,7 @@ const (
 
 	// EnableIPv6 is the default value for IPv6 enablement
 	EnableIPv6 = true
+
+	// MonitorQueueSize is the default value for the monitor queue size
+	MonitorQueueSize = 32768
 )

pkg/option/config.go

@@ -166,6 +166,10 @@ const (
 	// EnableIPv6Name is the name of the option to enable IPv6 support
 	EnableIPv6Name    = "enable-ipv6"
 	EnableIPv6NameEnv = "CILIUM_ENABLE_IPV6"
+
+	// MonitorQueueSizeName is the name of the option MonitorQueueSize
+	MonitorQueueSizeName    = "monitor-queue-size"
+	MonitorQueueSizeNameEnv = "CILIUM_MONITOR_QUEUE_SIZE"
 )
 
 // Available option for daemonConfig.Tunnel
@@ -375,6 +379,9 @@ type daemonConfig struct {
 
 	// EnableIPv6 is true when IPv6 is enabled
 	EnableIPv6 bool
+
+	// MonitorQueueSize is the size of the monitor event queue
+	MonitorQueueSize int
 }
 
 var (