From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 14 Oct 2001 07:50:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 14 Oct 2001 07:49:50 -0400 Received: from cs181088.pp.htv.fi ([213.243.181.88]:6528 "EHLO cs181088.pp.htv.fi") by vger.kernel.org with ESMTP id ; Sun, 14 Oct 2001 07:49:39 -0400 Message-ID: <3BC97BC5.9F341ACE@welho.com> Date: Sun, 14 Oct 2001 14:49:25 +0300 From: Mika Liljeberg X-Mailer: Mozilla 4.77 [en] (X11; U; Linux 2.4.10-ac10 i686) X-Accept-Language: en MIME-Version: 1.0 To: Andi Kleen CC: "David S. Miller" , linux-kernel@vger.kernel.org, kuznet@ms2.inr.ac.ru Subject: Re: TCP acking too fast In-Reply-To: <3BC94F3A.7F842182@welho.com> <20011014.020326.18308527.davem@redhat.com> <20011014.023948.95894368.davem@redhat.com> <20011014133004.34133@colin.muc.de> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andi Kleen wrote: > The only special case for PSH in RX left I can is in rcv_mss estimation, > where is assumes that a packet with PSH set is not full sized. A packet without PSH should be full size. Assuming the sender implemets SWS avoidance correctly, this should be a safe enough assumption. > On further > look the 2.4 tcp_measure_rcv_mss will never update rcv_mss for packets > which do have PSH set and in this case cause random ack behaviour depending > on the initial rcv_mss guess. > Not very nice; definitely violates the "be conservative what you accept" > rule. I'm not sure how to fix it, adding a fallback to every-two-packet-add > would pollute the fast path a bit. You're right. As far as I can see, it's not necessary to set the TCP_ACK_PUSHED flag at all (except maybe for SYN-ACK). I'm just writing a patch to clean this up. > -Andi Regards, MikaL