From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rick Jones Subject: Re: lowpri - RTO for unidirectional reciever Date: Tue, 09 Dec 2008 11:25:19 -0800 Message-ID: <493EC61F.7090806@hp.com> References: <493DD199.6080600@hp.com> <20081208.235622.149344934.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: David Miller Return-path: Received: from g5t0009.atlanta.hp.com ([15.192.0.46]:28270 "EHLO g5t0009.atlanta.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754016AbYLITZX (ORCPT ); Tue, 9 Dec 2008 14:25:23 -0500 In-Reply-To: <20081208.235622.149344934.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: David Miller wrote: > We should not use the SYN|ACK for RTT estimates. > > It's a bug, and in fact we used to, but I fixed that long > ago. > > Since there is no data in the packet, and it's therefore very small > compared to real data bearing packets, the RTT measured might be > artificially small and not really representative. A miracle occurs going from zero bytes of payload but several bytes of TCP options (scale and MSS) to having one byte of payload and no bytes of options? (Timestamp options remaining the same in both cases) rick jones