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From 9dcfa5bda8c03d0acecd87953ebfc78372bb9755 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Nikola=20Forr=C3=B3?= <nforro@redhat.com>
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Date: Tue, 28 Jun 2016 13:02:45 +0200
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Subject: [PATCH 07/17] socket.7: document SO_REUSEPORT option
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---
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man-pages/man7/socket.7 | 33 +++++++++++++++++++++++++++++++++
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1 file changed, 33 insertions(+)
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diff --git a/man-pages/man7/socket.7 b/man-pages/man7/socket.7
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index 17bd0c3..94c98b6 100644
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--- a/man-pages/man7/socket.7
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+++ b/man-pages/man7/socket.7
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@@ -649,6 +649,39 @@ with a specific port then it is not possible
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to bind to this port for any local address.
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Argument is an integer boolean flag.
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.TP
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+.BR SO_REUSEPORT
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+Permits multiple
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+.B AF_INET
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+or
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+.B AF_INET6
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+sockets to be bound to an identical socket address.
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+This option must be set on each socket (including the first socket)
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+prior to calling
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+.BR bind (2)
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+on the socket.
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+To prevent port hijacking,
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+all of the processes binding to the same address must have the same
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+effective UID.
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+This option can be employed with both TCP and UDP sockets.
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+
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+For TCP sockets, this option allows
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+.BR accept (2)
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+load distribution in a multi-threaded server to be improved by
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+using a distinct listener socket for each thread.
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+This provides improved load distribution as compared
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+to traditional techniques such using a single
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+.BR accept (2)ing
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+thread that distributes connections,
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+or having multiple threads that compete to
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+.BR accept (2)
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+from the same socket.
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+
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+For UDP sockets,
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+the use of this option can provide better distribution
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+of incoming datagrams to multiple processes (or threads) as compared
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+to the traditional technique of having multiple processes
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+compete to receive datagrams on the same socket.
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+.TP
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.B SO_SNDBUF
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Sets or gets the maximum socket send buffer in bytes.
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The kernel doubles this value (to allow space for bookkeeping overhead)
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--
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2.7.4
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