diff --git a/include/villas/nodes/cbuilder.h b/include/villas/nodes/cbuilder.h
index 06aab7861..169500230 100644
--- a/include/villas/nodes/cbuilder.h
+++ b/include/villas/nodes/cbuilder.h
@@ -45,7 +45,8 @@ struct cbuilder {
 	 * The simulation step is triggerd by a call to cbuilder_write().
 	 */
 	pthread_mutex_t mtx;
-	pthread_cond_t cv;
+	
+	int eventfd; /**< Eventfd for synchronizing cbuilder_read() / cbuilder_write() access. */
 };
 
 /** @} */
diff --git a/lib/nodes/cbuilder.c b/lib/nodes/cbuilder.c
index 759851d28..0b6e64977 100644
--- a/lib/nodes/cbuilder.c
+++ b/lib/nodes/cbuilder.c
@@ -4,6 +4,8 @@
  * @copyright 2017, Steffen Vogel
  **********************************************************************************/
 
+#include <sys/eventfd.h>
+
 #include "node.h"
 #include "log.h"
 #include "plugin.h"
@@ -60,7 +62,10 @@ int cbuilder_start(struct node *n)
 
 	/* Initialize mutex and cv */
 	pthread_mutex_init(&cb->mtx, NULL);
-	pthread_cond_init(&cb->cv, NULL);
+	
+	cb->eventfd = eventfd(0, 0);
+	if (cb->eventfd < 0)
+		return -1;
 
 	/* Currently only a single timestep per model / instance is supported */
 	cb->step = 0;
@@ -77,10 +82,14 @@ int cbuilder_start(struct node *n)
 
 int cbuilder_stop(struct node *n)
 {
+	int ret;
 	struct cbuilder *cb = n->_vd;
+	
+	ret = close(cb->eventfd);
+	if (ret)
+		return ret;
 
 	pthread_mutex_destroy(&cb->mtx);
-	pthread_cond_destroy(&cb->cv);
 
 	return 0;
 }
@@ -89,11 +98,13 @@ int cbuilder_read(struct node *n, struct sample *smps[], unsigned cnt)
 {
 	struct cbuilder *cb = n->_vd;
 	struct sample *smp = smps[0];
+	
+	uint64_t cntr;
+	
+	read(cb->eventfd, &cntr, sizeof(cntr));
 
 	/* Wait for completion of step */
 	pthread_mutex_lock(&cb->mtx);
-	while (cb->read >= cb->step)
-		pthread_cond_wait(&cb->cv, &cb->mtx);
 	
 	float data[smp->capacity];
 
@@ -125,13 +136,22 @@ int cbuilder_write(struct node *n, struct sample *smps[], unsigned cnt)
 	cb->model->code();
 
 	cb->step++;
+	
+	uint64_t incr = 1;
+	write(cb->eventfd, &incr, sizeof(incr));
 
-	pthread_cond_signal(&cb->cv);
 	pthread_mutex_unlock(&cb->mtx);
 
 	return 1;
 }
 
+int cbuilder_fd(struct node *n)
+{
+	struct cbuilder *cb = n->_vd;
+	
+	return cb->eventfd;
+}
+
 static struct plugin p = {
 	.name		= "cbuilder",
 	.description	= "RTDS CBuilder model",
@@ -143,7 +163,8 @@ static struct plugin p = {
 		.start		= cbuilder_start,
 		.stop		= cbuilder_stop,
 		.read		= cbuilder_read,
-		.write		= cbuilder_write
+		.write		= cbuilder_write,
+		.fd		= cbuilder_fd
 	}
 };
 
diff --git a/lib/nodes/loopback.c b/lib/nodes/loopback.c
index 995a8d055..cb866a5aa 100644
--- a/lib/nodes/loopback.c
+++ b/lib/nodes/loopback.c
@@ -57,7 +57,7 @@ int loopback_open(struct node *n)
 	if (ret)
 		return ret;
 
-	return queue_signalled_init(&l->queue, l->queuelen, &memtype_hugepage);
+	return queue_signalled_init(&l->queue, l->queuelen, &memtype_hugepage, QUEUE_SIGNALLED_EVENTFD);
 }
 
 int loopback_close(struct node *n)
@@ -116,19 +116,27 @@ char * loopback_print(struct node *n)
 	return buf;
 };
 
+int loopback_fd(struct node *n)
+{
+	struct loopback *l = n->_vd;
+	
+	return queue_signalled_fd(&l->queue);
+}
+
 static struct plugin p = {
 	.name = "loopback",
 	.description = "Loopback to connect multiple paths",
 	.type = PLUGIN_TYPE_NODE,
 	.node = {
 		.vectorize = 0,
-		.size  = sizeof(struct loopback),
-		.parse = loopback_parse,
-		.print = loopback_print,
-		.start = loopback_open,
-		.stop  = loopback_close,
-		.read  = loopback_read,
-		.write = loopback_write
+		.size	= sizeof(struct loopback),
+		.parse	= loopback_parse,
+		.print	= loopback_print,
+		.start	= loopback_open,
+		.stop	= loopback_close,
+		.read	= loopback_read,
+		.write	= loopback_write,
+		.fd	= loopback_fd
 	}
 };
 
diff --git a/lib/nodes/shmem.c b/lib/nodes/shmem.c
index 6b16a843f..688dcb22b 100644
--- a/lib/nodes/shmem.c
+++ b/lib/nodes/shmem.c
@@ -186,7 +186,7 @@ char * shmem_print(struct node *n)
 	}
 
 	return buf;
-};
+}
 
 static struct plugin p = {
 	.name = "shmem",
@@ -194,13 +194,13 @@ static struct plugin p = {
 	.type = PLUGIN_TYPE_NODE,
 	.node = {
 		.vectorize = 0,
-		.size = sizeof(struct shmem),
-		.parse = shmem_parse,
-		.print = shmem_print,
-		.start = shmem_open,
-		.stop = shmem_close,
-		.read = shmem_read,
-		.write = shmem_write
+		.size	= sizeof(struct shmem),
+		.parse	= shmem_parse,
+		.print	= shmem_print,
+		.start	= shmem_open,
+		.stop	= shmem_close,
+		.read	= shmem_read,
+		.write	= shmem_write
 	}
 };
 
diff --git a/lib/nodes/websocket.c b/lib/nodes/websocket.c
index 95f99a641..52ebb1e72 100644
--- a/lib/nodes/websocket.c
+++ b/lib/nodes/websocket.c
@@ -346,7 +346,7 @@ int websocket_start(struct node *n)
 	if (ret)
 		return ret;
 
-	ret = queue_signalled_init(&w->queue, DEFAULT_WEBSOCKET_QUEUELEN, &memtype_hugepage);
+	ret = queue_signalled_init(&w->queue, DEFAULT_WEBSOCKET_QUEUELEN, &memtype_hugepage, 0);
 	if (ret)
 		return ret;
 
@@ -558,6 +558,13 @@ char * websocket_print(struct node *n)
 	return buf;
 }
 
+int websocket_fd(struct node *n)
+{
+	struct websocket *w = n->_vd;
+	
+	return queue_signalled_fd(&w->queue);
+}
+
 static struct plugin p = {
 	.name		= "websocket",
 	.description	= "Send and receive samples of a WebSocket connection (libwebsockets)",
@@ -573,7 +580,8 @@ static struct plugin p = {
 		.read		= websocket_read,
 		.write		= websocket_write,
 		.print		= websocket_print,
-		.parse		= websocket_parse
+		.parse		= websocket_parse,
+		.fd		= websocket_fd
 	}
 };