Enable TCP_NODELAY

common.c

@@ -33,6 +33,7 @@
 #include <setjmp.h>
 #include <inttypes.h>
 #include <arpa/inet.h>
+#include <netinet/tcp.h>
 
 /// Shorthand to set an error and return failure from the function
 #define FAIL(...)                                                              \

degesch.c

@@ -4732,6 +4732,12 @@ irc_finish_connection (struct server *s, int socket)
 {
 	struct app_context *ctx = s->ctx;
 
+	// Most of our output comes from the user one full command at a time and we
+	// use output buffering, so it makes a lot of sense to avoid these delays
+	int yes = 1;
+	soft_assert (setsockopt (socket, IPPROTO_TCP, TCP_NODELAY,
+		&yes, sizeof yes) != -1);
+
 	set_blocking (socket, false);
 	s->socket = socket;
 	s->transport = get_config_boolean (s->config, "tls")

kike.c

@@ -3421,6 +3421,13 @@ irc_try_fetch_client (struct server_context *ctx, int listen_fd)
 	c->ping_timer.dispatcher = on_client_ping_timer;
 	c->ping_timer.user_data = c;
 
+	// A little bit questionable once the traffic gets high enough (IMO),
+	// but it reduces silly latencies that we don't need because we already
+	// do buffer our output
+	int yes = 1;
+	soft_assert (setsockopt (fd, IPPROTO_TCP, TCP_NODELAY,
+		&yes, sizeof yes) != -1);
+
 	set_blocking (fd, false);
 	client_update_poller (c, NULL);
 	client_set_kill_timer (c);