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From: "Seymour, Shane M" <shane.seymour@hpe.com>
To: "netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: [PATCH net-next] tcp: increase size at which tcp_bound_to_half_wnd bounds to > TCP_MSS_DEFAULT
Date: Tue, 28 Jun 2016 04:33:30 +0000	[thread overview]
Message-ID: <CS1PR84MB0295E420892A535E40FE338EFD220@CS1PR84MB0295.NAMPRD84.PROD.OUTLOOK.COM> (raw)

In previous commit 01f83d69844d307be2aa6fea88b0e8fe5cbdb2f4
the following comments were added:

"When peer uses tiny windows, there is no use in packetizing to sub-MSS
pieces for the sake of SWS or making sure there are enough packets in
the pipe for fast recovery."

The test should be > TCP_MSS_DEFAULT not >= 512. This allows low end
devices that send an MSS of 536 (TCP_MSS_DEFAULT) to see better network
performance by sending it 536 bytes of data at a time instead of bounding
to half window size (268). Other network stacks work this way, e.g. HP-UX.

Signed-off-by: Shane Seymour <shane.seymour@hpe.com>
---
--- b/include/net/tcp.h	2016-06-23 20:59:14.521686048 -0500
+++ a/include/net/tcp.h	2016-06-15 17:19:21.964821477 -0500
@@ -589,7 +589,7 @@ static inline int tcp_bound_to_half_wnd(
 	 * On the other hand, for extremely large MSS devices, handling
 	 * smaller than MSS windows in this way does make sense.
 	 */
-	if (tp->max_window > TCP_MSS_DEFAULT)
+	if (tp->max_window >= 512)
 		cutoff = (tp->max_window >> 1);
 	else
 		cutoff = tp->max_window;

             reply	other threads:[~2016-06-28  6:08 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-28  4:33 Seymour, Shane M [this message]
2016-06-28 11:58 ` [PATCH net-next] tcp: increase size at which tcp_bound_to_half_wnd bounds to > TCP_MSS_DEFAULT Eric Dumazet
2016-06-28 21:54   ` Seymour, Shane M
2016-06-28 22:35     ` Eric Dumazet
2016-06-28 22:51       ` Seymour, Shane M
2016-06-28 22:35     ` Neal Cardwell

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