From: Fan Du <fan.du@intel.com>
Date: Fri, 6 Mar 2015 03:18:22 +0000 (+0800)
Subject: ipv4: Raise tcp PMTU probe mss base size
X-Git-Tag: firefly_0821_release~176^2~1974^2~323^2~3
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=dcd8fb8533ceb493146ce030d15f7965b82d0c27;p=firefly-linux-kernel-4.4.55.git

ipv4: Raise tcp PMTU probe mss base size

Quotes from RFC4821 7.2.  Selecting Initial Values

   It is RECOMMENDED that search_low be initially set to an MTU size
   that is likely to work over a very wide range of environments.  Given
   today's technologies, a value of 1024 bytes is probably safe enough.
   The initial value for search_low SHOULD be configurable.

Moreover, set a small value will introduce extra time for the search
to converge. So set the initial probe base mss size to 1024 Bytes.

Signed-off-by: Fan Du <fan.du@intel.com>
Acked-by: John Heffner <johnwheffner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/include/net/tcp.h b/include/net/tcp.h
index f87599d5af82..834089b0cffc 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -65,7 +65,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo);
 #define TCP_MIN_MSS		88U
 
 /* The least MTU to use for probing */
-#define TCP_BASE_MSS		512
+#define TCP_BASE_MSS		1024
 
 /* After receiving this amount of duplicate ACKs fast retransmit starts. */
 #define TCP_FASTRETRANS_THRESH 3