From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-x232.google.com (mail-wi0-x232.google.com [IPv6:2a00:1450:400c:c05::232]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by huchra.bufferbloat.net (Postfix) with ESMTPS id 9B0A821F1A9 for ; Mon, 24 Feb 2014 08:14:20 -0800 (PST) Received: by mail-wi0-f178.google.com with SMTP id cc10so3253879wib.17 for ; Mon, 24 Feb 2014 08:14:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; bh=Jo+nuB7P6A9qF3XZ4QkUmWcckOFuCPeDLxzYKJ2yRgU=; b=SVMxf0QmIndglXSQNiUT3tctDTXX8qrCZjOunN+L10iqhmilQ28xhmZurCo1U+BhYs yaSHZIAETgTs4xCacjJ/iAubDUzSVeQc7lQE1HHkIukbYDae2h/Ov1YnKEXL694LgRN9 Tm3cF1gOt4ZbLTEqVeCldtKJzp0z7PYmXNMz6pY4q7453YkVua6HCEnz364+SSpIPL5h 1HB73t7wpC4SMV2VAfldPvdxNUD+9+g2f7gScY/Np+gdKOmJoWbpL2OyojxmPDO6TtOU lCPCuwuOqBP+VsihbzfxCmU1nk0Np1Ld2wCadiGAOx9suFfazVRvoVGpOvX+ov5pY3j8 LSkg== MIME-Version: 1.0 X-Received: by 10.180.188.169 with SMTP id gb9mr15198451wic.17.1393258458307; Mon, 24 Feb 2014 08:14:18 -0800 (PST) Received: by 10.216.8.1 with HTTP; Mon, 24 Feb 2014 08:14:18 -0800 (PST) In-Reply-To: References: <4E5BC321-2054-4364-BECC-DF34E0D20380@gmail.com> Date: Mon, 24 Feb 2014 11:14:18 -0500 Message-ID: From: Dave Taht To: Rich Brown Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: cerowrt-devel Subject: Re: [Cerowrt-devel] Equivocal results with using 3.10.28-14 X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 24 Feb 2014 16:14:21 -0000 On Mon, Feb 24, 2014 at 10:51 AM, Dave Taht wrote: > On Mon, Feb 24, 2014 at 9:36 AM, Rich Brown wro= te: >> >> CeroWrt 3.10.28-14 is doing a good job of keeping latency low. But... it= has two other effects: >> >> - I don't get the full "7 mbps down, 768 kbps up" as touted by my DSL pr= ovider (Fairpoint). In fact, CeroWrt struggles to get above 6.0/0.6 mbps. > > 0) try the tcp_upload or tcp_download or tcp_bidir tests to get > results closer to what your provider claims. > > since your plots are pretty sane, you can get cleaner ones with using > the 'totals' plot type > and/or comparing multiple runs to get a cdf > > -p totals or -p icmp (theres a few different ones, --list-plots > > -i somerun.json.gz -i somerun2.json.gz > > > 1) http://richb-hanover.com/wp-content/uploads/2014/02/6854-777-dflt-sqm-= disabled1.png > > is your baseline without SQM? > > If so why do you compare the providers stated rate... > > with the measured rate with/without SQM? > > These are two measures of the truth - one with and without a change. > > Vs a providers claim for link rate that doesn't account for real > packet dynamics. I awoke mildly grumpy this morning, sorry. The the sqm-disabled link above shows you getting less than a mbit down under the providers default settings. So rather than saying you lose 10% of link bandwidth relative to the stated ISP specification, I prefer to think you are getting 6x more usable bandwidth from using SQM, and somewhere around 1/25th or more less latency. Making tcp's congestion avoidance work rapidly and avoiding bursty packet loss leads to more usable bandwidth. > 2) the netperf reporting interval is too high to get good measurements > at below a few > mbit, so you kind of have to give up on the upload chart at these > rates. (totals chart is > clearer) > > Note that the tcp acks are invisible - you are getting >6mbit down, > and sending back approximately > 150kbit in acks which we can't easily measure. The overhead in the > measurement streams is > relative to the RTT as well. > > I'd really like to get to a test that emulated tcp and got a fully > correct measurement. > > 3) Generally using a larger fq_codel target will give you better > upload throughput and > better utiliziation at these rates. try target 40ms as a start. We've > embedded a version > of the calculation in the latest cero build attempts (but other stuff is = broke) > > nfq_codel seems also do to give a better balance between up and > downloads at low rates, > also with a larger target. > > it looks like overhead 44 is about right and your first set of charts > about right. so if you could repeat your first set of tests changing the target to at le= ast 40ms on the upload, and trying both nfq_codel and fq_codel, you'll be getti= ng somewhere. nfq_codel behaves more like SFQ, and is probably closer to what more people want at these speeds. > > > >> >> - When I adjust the SQM parameters to get close to those numbers, I get = increasing levels of packet loss (5-8%) during a concurrent ping test. > > Shows the pings are now accruing delay. > >> >> So my question to the group is whether this behavior makes sense: that w= e can have low latency while losing ~10% of the link capacity, or that gett= ing close to the link capacity should induce large packet loss... > > You never had the 10% in the first place. > >> >> Experimental setup: >> >> I'm using a Comtrend 583-U DSL modem, that has a sync rate of 7616 kbps = down, 864 kbps up. Theoretically, I should be able to tell SQM to use numbe= rs a bit lower than those values, with an ATM plus header overhead with def= ault settings. >> >> I have posted the results of my netperf-wrapper trials at http://richb-h= anover.com - There are a number of RRUL charts, taken with different link r= ates configured, and with different link layers. >> >> I welcome people's thoughts for other tests/adjustments/etc. >> >> Rich Brown >> Hanover, NH USA >> >> PS I did try the 3.10.28-16, but ran into troubles with wifi and etherne= t connectivity. I must have screwed up my local configuration - I was doing= it quickly - so I rolled back to 3.10.28.14. > > > manually adjust the target. > >> _______________________________________________ >> Cerowrt-devel mailing list >> Cerowrt-devel@lists.bufferbloat.net >> https://lists.bufferbloat.net/listinfo/cerowrt-devel > > > > -- > Dave T=E4ht > > Fixing bufferbloat with cerowrt: http://www.teklibre.com/cerowrt/subscrib= e.html --=20 Dave T=E4ht Fixing bufferbloat with cerowrt: http://www.teklibre.com/cerowrt/subscribe.= html