From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-vw0-f43.google.com (mail-vw0-f43.google.com [209.85.212.43]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id B4932200994; Thu, 24 Nov 2011 01:38:15 -0800 (PST) Received: by vbbfq11 with SMTP id fq11so3250950vbb.16 for ; Thu, 24 Nov 2011 01:38:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:date:message-id:subject:from:to:content-type :content-transfer-encoding; bh=dBcYjpV8jdoYz6m6Rfj5Q/29o91C7aIAOrKcGZ5HipQ=; b=yH8btLqWM6ERplay3/NSZz+oLI5Z+C350T8mV6NcDD0OEybDXIs9ZtHR8qWdyrFozR 9IgCa4GkHU2XSWKdt0VDaZLAgv1jGsZ/tnnpb4QkQH/aUzS7+pWazS0fM7tcUWtgp2IC TU59gMgYers7wDbYP1WbO/ieiUviy7yNJ33tM= MIME-Version: 1.0 Received: by 10.182.207.104 with SMTP id lv8mr9175939obc.36.1322127494107; Thu, 24 Nov 2011 01:38:14 -0800 (PST) Received: by 10.182.193.65 with HTTP; Thu, 24 Nov 2011 01:38:14 -0800 (PST) Date: Thu, 24 Nov 2011 10:38:14 +0100 Message-ID: From: Dave Taht To: bloat-devel , bloat Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Subject: [Bloat] Analyzing fairness across multiple tcp flows in a packet capture? 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: Thu, 24 Nov 2011 09:38:16 -0000 As a result of Byte queue limits actually giving the packet scheduler layer something to do, at least on ethernet, I've given up on wireless for a while. I've been fiddling with QFQ (the quick fair scheduler) and Red, to get a feel for how the results 'look', mostly in tcptrace + xplot. I dumped the latest wip on that up on github before I dared boot into a BQL enabled kernel... https://github.com/dtaht/deBloat/tree/master/wip (eqfq and various forms of eqfq.red are what I'm mostly fiddling with - most of the other scripts are garbage which I'll clean up in a bit) You'd need a debloat-testing or bql enabled kernel and the latest iproute2 = code to mess with QFQ. The good news is that a home router CAN run the above scripts - and does run at well over 100Mbit with them over ethernet. While in my limited testing QFQ feels like a win at these timescales and traffic volumes... reducing interstream latency to less than 2ms for the first new stream, as one example - I'd like to be doing something comprehensive, not-ad-hoc, and repeatable by others. it's really, really hard to 'see' what's really going on, in particular measuring how well flows are interleaved... So I'm curious if there is any tool out there that= can take a packet capture and determine that? (WFI (worst case fair index)) Adding netperf's tcp_rr test to the list seems like a good idea... I did things like google for things like "measuring fairness across flows" - which actually was quite interesting, this paper was kind of encouraging re the wireless mesh problem. ( http://www.ecsl.cs.sunysb.edu/tr/TR210.pdf ) but I digress. At the moment I'm fiddling with ethernet. and poked through wireshark's plugins, but otherwise came up empty. Alright, alright, enough on wired (I'm happy about wired at the moment) Wireless, not so much. I had meant to mention this wireless paper weeks ago: www-users.aston.ac.uk/~pengx1/QoS-project/ants-08.pdf It shows how EDCA (802.11e) works on 'g', and suggests an interesting wireshark filter for analyzing real behavior on the air, and the ironic money quote, for me, was... "Fig. 5 demonstrates the effect of introducing 3 TCP streams using legacy DCF at t =3D 30 and t =3D 60 seconds, respectively. We can clearly see that the lack of service differentiation results in the individual stations sharing the available bandwidth equally" I'm figuring the results of that wireshark filter will be 'interesting' on wireless-n as presently implemented. tcp's RTT differences does interesting things... --=20 Dave T=E4ht http://www.bufferbloat.net