Redis.conf comment about tcp-backlog option improved.

redis.conf

@@ -44,7 +44,13 @@ pidfile /var/run/redis.pid
 # If port 0 is specified Redis will not listen on a TCP socket.
 port 6379
 
-# TCP listen() backlog
+# TCP listen() backlog.
+#
+# In high requests-per-second environments you need an high backlog in order
+# to avoid slow clients connections issues. Note that the Linux kernel
+# will silently truncate it to the value of /proc/sys/net/core/somaxconn so
+# make sure to raise both the value of somaxconn and tcp_max_syn_backlog
+# in order to get the desired effect.
 tcp-backlog 511
 
 # By default Redis listens for connections from all the network interfaces