From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH net-next] tcp: increase size at which tcp_bound_to_half_wnd bounds to > TCP_MSS_DEFAULT Date: Tue, 28 Jun 2016 13:58:10 +0200 Message-ID: <1467115090.6850.202.camel@edumazet-glaptop3.roam.corp.google.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: "netdev@vger.kernel.org" To: "Seymour, Shane M" Return-path: Received: from mail-wm0-f46.google.com ([74.125.82.46]:37907 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752185AbcF1L60 (ORCPT ); Tue, 28 Jun 2016 07:58:26 -0400 Received: by mail-wm0-f46.google.com with SMTP id r201so24138471wme.1 for ; Tue, 28 Jun 2016 04:58:17 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 2016-06-28 at 04:33 +0000, Seymour, Shane M wrote: > 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. Trying to cope with ridiculous windows these days is really a waste of time, as we perform this check for all tcp sendmsg() calls :( Anyway, your patch is reversed.