From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-21-ewr.dyndns.com (mxout-046-ewr.mailhop.org [216.146.33.46]) by lists.bufferbloat.net (Postfix) with ESMTP id A6BB62E011F for ; Fri, 11 Mar 2011 16:00:33 -0800 (PST) Received: from scan-22-ewr.mailhop.org (scan-22-ewr.local [10.0.141.244]) by mail-21-ewr.dyndns.com (Postfix) with ESMTP id C37204B16 for ; Sat, 12 Mar 2011 00:00:32 +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-21-ewr.dyndns.com (Postfix) with ESMTP id E1D9017B4 for ; Sat, 12 Mar 2011 00:00:27 +0000 (UTC) Received: by eydd26 with SMTP id d26so1275362eyd.16 for ; Fri, 11 Mar 2011 16:00:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:from:content-type:content-transfer-encoding :subject:date:message-id:to:mime-version:x-mailer; bh=SzR++a0E7/szib/LWd9xsRAXFcKa5YjUyfrsmSDNCrg=; b=rbWvbK34GeBI1q2p3JsQDNuz8o8JzIWWmX4AGMuR9UwzXAI1XZFxgOyCIPPrJKTL4H 8ssonVQoqXYxcMWISKRN1BDEEoF8KiPn3h9IUxTWOCvRkXNL2bdPquOyLEqomIpzImTT wWA/20R2eoal+UEA+DyK2onFk8Z8oSBKgRqb0= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:content-type:content-transfer-encoding:subject:date:message-id :to:mime-version:x-mailer; b=Rbehm+4k90eE7SrRGw96CQoTcBM5DkRjmQiEav3OZfF4lTf1klqzBnjsDUpsK5Ymjc Wxgpxy27juySBqi5QJOxaZxqnOvii7dKunelcVZ+99jS1cb7OGVGHA4yWHT9Uwgrpegj veAhJtf4j2gVK16yZdJR2/v7lc+i0CM4+bC6s= Received: by 10.213.17.8 with SMTP id q8mr9575eba.141.1299888027184; Fri, 11 Mar 2011 16:00:27 -0800 (PST) Received: from [192.168.239.42] (xdsl-83-150-84-172.nebulazone.fi [83.150.84.172]) by mx.google.com with ESMTPS id t50sm3902173eeh.6.2011.03.11.16.00.26 (version=TLSv1/SSLv3 cipher=OTHER); Fri, 11 Mar 2011 16:00:26 -0800 (PST) From: Jonathan Morton Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Date: Sat, 12 Mar 2011 02:00:25 +0200 Message-Id: <16808EAB-2F52-4D32-8A8C-2AE09CD4D103@gmail.com> To: bloat@lists.bufferbloat.net Mime-Version: 1.0 (Apple Message framework v1082) X-Mailer: Apple Mail (2.1082) Subject: [Bloat] Measuring latency-under-load consistently 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, 12 Mar 2011 00:00:33 -0000 I'm currently resurrecting my socket-programming skills (last used = almost 10 years ago when IPv6 really *was* experimental) in the hope of = making a usable latency-under-load tester. This could be run in = server-mode on one host, and then as a client on another host could be = pointed at the server, followed by several minutes of churning and some = nice round numbers. It would need to make multiple TCP connections simultaneously, one of = which would be used to measure latency (using NODELAY marked sockets), = and one or more others used to load the network and measure goodput. It = would automatically determine how long to run in order to get a reliable = result that can't easily be challenged by (eg.) an ISP. The output metrics would be: 1) Average goodput for uplink and downlink, for single flows and = multiple flows, in binary megabytes per second. Just for laughs, I = might also add the equivalent gigabytes-per-month figures. 2) Maximum latency (in the parallel "interactive" flow) under load, = expressed in Hz rather than milliseconds. This gives a number that gets = bigger for better performance, which is much easier for laymen to = understand. 3) Flow smoothness, measured as the maximum time between sequential = received data for any continuous flow, also expressed in Hz. This is an = important metric for video and radio streaming, and one which CUBIC will = probably do extremely badly at if there are large buffers in the path = (without AQM or Blackpool). Any thoughts on this idea? - Jonathan