From 9dcfa5bda8c03d0acecd87953ebfc78372bb9755 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Nikola=20Forr=C3=B3?= <nforro@redhat.com>
Date: Tue, 28 Jun 2016 13:02:45 +0200
Subject: [PATCH 07/17] socket.7: document SO_REUSEPORT option

---
 man-pages/man7/socket.7 | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/man-pages/man7/socket.7 b/man-pages/man7/socket.7
index 17bd0c3..94c98b6 100644
--- a/man-pages/man7/socket.7
+++ b/man-pages/man7/socket.7
@@ -649,6 +649,39 @@ with a specific port then it is not possible
 to bind to this port for any local address.
 Argument is an integer boolean flag.
 .TP
+.BR SO_REUSEPORT
+Permits multiple
+.B AF_INET
+or
+.B AF_INET6
+sockets to be bound to an identical socket address.
+This option must be set on each socket (including the first socket)
+prior to calling
+.BR bind (2)
+on the socket.
+To prevent port hijacking,
+all of the processes binding to the same address must have the same
+effective UID.
+This option can be employed with both TCP and UDP sockets.
+
+For TCP sockets, this option allows
+.BR accept (2)
+load distribution in a multi-threaded server to be improved by
+using a distinct listener socket for each thread.
+This provides improved load distribution as compared
+to traditional techniques such using a single
+.BR accept (2)ing
+thread that distributes connections,
+or having multiple threads that compete to
+.BR accept (2)
+from the same socket.
+
+For UDP sockets,
+the use of this option can provide better distribution
+of incoming datagrams to multiple processes (or threads) as compared
+to the traditional technique of having multiple processes
+compete to receive datagrams on the same socket.
+.TP
 .B SO_SNDBUF
 Sets or gets the maximum socket send buffer in bytes.
 The kernel doubles this value (to allow space for bookkeeping overhead)
-- 
2.7.4