From 6b83d27d53e24bfe7c37e9f7578cfec9540aae1f Mon Sep 17 00:00:00 2001
From: MadCamel <madcamel@gmail.com>
Date: Sun, 7 Apr 2013 17:07:03 -0400
Subject: 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.
---
src/common/socket.cpp | 13 +++++++++++--
1 file 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);
--
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