From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Seymour, Shane M" 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 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT To: "netdev@vger.kernel.org" Return-path: Received: from mail-bn1bn0107.outbound.protection.outlook.com ([157.56.110.107]:8962 "EHLO na01-bn1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751017AbcF1GIr convert rfc822-to-8bit (ORCPT ); Tue, 28 Jun 2016 02:08:47 -0400 Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: 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 --- --- 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;