Enable tcp_thin socket optimizations on Linux

See kernel/Documentation/networking/tcp-thin.txt
These TCP optimizations were designed for the specific purpose of
low latency TCP gameservers and can help reduce latency in adverse
network conditions.

1 files changed, 11 insertions, 2 deletions

diff --git a/src/common/socket.cpp b/src/common/socket.cpp
index cc6e4b3..e79f27a 100644
--- a/src/common/socket.cpp
+++ b/src/common/socket.cpp
@@ -117,10 +117,19 @@ static void connect_client (int listen_fd)
     setsockopt (fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof yes);
     /// Send packets as soon as possible
     /// even if the kernel thinks there is too little for it to be worth it!
-    // I'm not convinced this is a good idea; although in minimizes the
-    // latency for an individual write, it increases traffic in general.
+    /// Testing shows this is indeed a good idea.
     setsockopt (fd, IPPROTO_TCP, TCP_NODELAY, &yes, sizeof yes);
 
+    // Linux-ism: Set socket options to optimize for thin streams
+    // See http://lwn.net/Articles/308919/ and
+    // Documentation/networking/tcp-thin.txt .. Kernel 3.2+
+#ifdef TCP_THIN_LINEAR_TIMEOUTS
+    setsockopt(fd, IPPROTO_TCP, TCP_THIN_LINEAR_TIMEOUTS, &yes, sizeof yes);
+#endif
+#ifdef TCP_THIN_DUPACK
+    setsockopt(fd, IPPROTO_TCP, TCP_THIN_DUPACK, &yes, sizeof yes);
+#endif
+
     FD_SET (fd, &readfds);
 
     fcntl (fd, F_SETFL, O_NONBLOCK);