From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-22-ewr.dyndns.com (mxout-101-ewr.mailhop.org [216.146.33.101]) by lists.bufferbloat.net (Postfix) with ESMTP id E599E2E062E for ; Sat, 19 Mar 2011 10:44:17 -0700 (PDT) Received: from scan-21-ewr.mailhop.org (scan-21-ewr.local [10.0.141.243]) by mail-22-ewr.dyndns.com (Postfix) with ESMTP id E117C31BC0 for ; Sat, 19 Mar 2011 17:44:16 +0000 (UTC) X-Spam-Score: -1.0 (-) X-Mail-Handler: MailHop by DynDNS X-Originating-IP: 209.85.215.171 Received: from mail-ey0-f171.google.com (mail-ey0-f171.google.com [209.85.215.171]) by mail-22-ewr.dyndns.com (Postfix) with ESMTP id C11CB31469 for ; Sat, 19 Mar 2011 17:44:11 +0000 (UTC) Received: by eydd26 with SMTP id d26so1441671eyd.16 for ; Sat, 19 Mar 2011 10:44:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:subject:mime-version:content-type:from :in-reply-to:date:cc:content-transfer-encoding:message-id:references :to:x-mailer; bh=Olj432S8Am/gfdYp8uRsHMXfCCgycWes5bF7YY3U3QA=; b=QVDCcGIYVKdz8TInZ5zxJkr4IGHPm+Vl7X/J9I+eidigzH0SZCwd6o+EgJcfneKOd4 ZopK1VIQRG/EqpJuEELhw13mDPznPMRb47iUmZ8O37fIUf7RGtRyMlunAt9edqPqehj0 WpDjM73WL9Bg0caNR+udZSxsK4xvucPOnCmic= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:mime-version:content-type:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to:x-mailer; b=bUTF58GgxiwBwVYu3AkqOb5BdMgnyT5NBLmwUWuxag/ndBy2N8SEehcgrhe2Mpr8+k IauvD0D1zhq/pVhAVZwYu9dWfpCKlPUS4Kkyqndxi8btiGmk/cMkrOYh210GC/KvAohN 8L9hyTG9vlmCJfwagaABAKCHqlCF6Oe0oYS2o= Received: by 10.14.137.200 with SMTP id y48mr468685eei.166.1300556651081; Sat, 19 Mar 2011 10:44:11 -0700 (PDT) Received: from [192.168.239.42] (xdsl-83-150-84-172.nebulazone.fi [83.150.84.172]) by mx.google.com with ESMTPS id x54sm731659eeh.12.2011.03.19.10.44.10 (version=TLSv1/SSLv3 cipher=OTHER); Sat, 19 Mar 2011 10:44:10 -0700 (PDT) Mime-Version: 1.0 (Apple Message framework v1082) Content-Type: text/plain; charset=us-ascii From: Jonathan Morton In-Reply-To: <4D829B58.1070601@swin.edu.au> Date: Sat, 19 Mar 2011 19:44:09 +0200 Content-Transfer-Encoding: quoted-printable Message-Id: References: <0D59AD34-AA64-4376-BB8E-58C5D378F488@gmail.com> <4D829B58.1070601@swin.edu.au> To: grenville armitage X-Mailer: Apple Mail (2.1082) Cc: bloat@lists.bufferbloat.net Subject: Re: [Bloat] Progress with latency-under-load tool X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 19 Mar 2011 17:44:18 -0000 On 18 Mar, 2011, at 1:38 am, grenville armitage wrote: > So, this is probably tangential to what the latency-under-load tool is > aiming to achieve, but we have a tool that can be used to measure > RTT between two points (e.g. either side of an 802.11 link) using > tcpdump on consumer-grade PCs and no active probing (ala ping). The average actual consumer isn't going to be able to set that up. = Sounds great for research though. After much headbutting of walls, my tool finally seems to work. The = biggest challenge turned out to be getting both ends to shut down = gracefully (and more-or-less simultaneously) after each phase of the = test. With that solved, I'm now running a full test run between two of my less = powerful machines on a wired LAN. I can immediately see that even a = 1996-vintage PC can saturate a 100Mbps link hard enough to exhibit = bloat-related problems. Once again, anyone claiming this to be a "new = problem" is grossly misinformed. More details when I have them. - Jonathan