[tx] increase timeres on TX pressure and reduce log noise

when TX sockets are overloaded, we spend more time spitting out
logs than recovering from the overload. ifdef the logging on
critical path out (still available with debug build).

also drastically reduce the waiting time by 64x.

this changes increases UDP perf on 3 nodes by 200%

Signed-off-by: Fabio M. Di Nitto <fdinitto@redhat.com>

libknet/threads_tx.c

@@ -74,12 +74,14 @@ static int _dispatch_to_links(knet_handle_t knet_h, struct knet_host *dst_host,
 				} else {
 					progress = 0;
 				}
+#ifdef DEBUG
 				log_debug(knet_h, KNET_SUB_TX, "Unable to send all (%d/%d) data packets to host %s (%u) link %s:%s (%u)",
 					  sent_msgs, msg_idx,
 					  dst_host->name, dst_host->host_id,
 					  dst_host->link[dst_host->active_links[link_idx]].status.dst_ipaddr,
 					  dst_host->link[dst_host->active_links[link_idx]].status.dst_port,
 					  dst_host->link[dst_host->active_links[link_idx]].link_id);
+#endif
 				goto retry;
 			}
 			if (!progress) {

libknet/transport_sctp.c

@@ -306,8 +306,10 @@ static int sctp_transport_tx_sock_error(knet_handle_t knet_h, int sockfd, int re
 				break;
 		}
 		if (recv_errno == EAGAIN) {
+#ifdef DEBUG
 			log_debug(knet_h, KNET_SUB_TRANSP_SCTP, "Sock: %d is overloaded. Slowing TX down", sockfd);
-			usleep(KNET_THREADS_TIMERES * 4);
+#endif
+			usleep(KNET_THREADS_TIMERES / 16);
 			return 1;
 		}
 		return -1;

libknet/transport_udp.c

@@ -356,8 +356,10 @@ static int udp_transport_tx_sock_error(knet_handle_t knet_h, int sockfd, int rec
 {
 	if (recv_err < 0) {
 		if ((recv_errno == ENOBUFS) || (recv_errno == EAGAIN)) {
+#ifdef DEBUG
 			log_debug(knet_h, KNET_SUB_TRANSP_UDP, "Sock: %d is overloaded. Slowing TX down", sockfd);
-			usleep(KNET_THREADS_TIMERES * 4);
+#endif
+			usleep(KNET_THREADS_TIMERES / 16);
 			return 1;
 		}
 		read_errs_from_sock(knet_h, sockfd);