From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from nm53-vm0.bullet.mail.ne1.yahoo.com (nm53-vm0.bullet.mail.ne1.yahoo.com [98.138.121.192]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id 1028321F11D for ; Wed, 5 Dec 2012 12:33:48 -0800 (PST) Received: from [98.138.226.176] by nm53.bullet.mail.ne1.yahoo.com with NNFMP; 05 Dec 2012 20:33:45 -0000 Received: from [98.138.87.1] by tm11.bullet.mail.ne1.yahoo.com with NNFMP; 05 Dec 2012 20:33:45 -0000 Received: from [127.0.0.1] by omp1001.mail.ne1.yahoo.com with NNFMP; 05 Dec 2012 20:33:44 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 999085.38177.bm@omp1001.mail.ne1.yahoo.com Received: (qmail 6955 invoked by uid 60001); 5 Dec 2012 20:33:44 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.com; s=s1024; t=1354739624; bh=ruX/TBGd1BCfzJ4hdREMoNCZk199T4SBpRQl46gNlRs=; h=X-YMail-OSG:Received:X-Rocket-MIMEInfo:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:Cc:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=d4MZ2+drzQOu2N1XFkfsqJv6GhgHVIeauYpc1wmNKuh7+unK5sJIZ7rwy8paC5mndrV/CYMLKepJHNxeAYXmwnteYxQvVphRZNuFxBGnx89Dno5In8P6juchPlNlbOpkjY/jWZbyi8ve87NPOPvFchO8ss2de00AQd+zGfYapxc= DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Rocket-MIMEInfo:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:Cc:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=vTurehyFvXMaM+Q29JVA7H5NYuAYHYjOtNex2E7TOTlwhKgRNq+Y9W/KwSLfGmdlF5rzRtGt5JlUAe38LeuGwQlkxLxNWXLY+gLziHCw9NjOysKcixEPYw7x/ZTNcMRYlTI7BSxOaQ94Db4vDzhItjxRMD2OBGrU9UKzBS4Tcrw=; X-YMail-OSG: zEgt344VM1njYQBenPyrneU1BF7Utyi6yO6Da23Wcms0Rjo IyuApM0HIMg3D233f3iXND4bKTsrghVC6.HZ7URWqGpzub4yIqHZwnybzLQK G8XQVMqSg8oP2NfSowiZUvPZUl.fDu1vocD6vO.HMtbiYUD9CUMy0_AlEhiK KcsiD5DJ8MVIHl8Tgw8Zs2aW7.lsRE0zdh1Z.kVo44L3xRNSn2cs2JdpVRUI Zc54QKNMg..ww.ymH9EtyuKLxadicJeNCmLXK7BBCgPrWqIC_f3lv6sJWTYG Bn_5oX7grSZ.XH04J3_9EJI3zgDmxluisLIxMZOQKJrFXYAzgiptHS1Gjylz Re1tpxqNWSEMgJhJXl6JgJNJrI2kntuI9nTnjbeD0lcjLZWSDcJzUdc56GQK sYOAjx9u_yBI7WtFgGRnvFy7R8PBCKvB5YNB_NL11PRHknOs9vnU2hEE4EIu LoRMqI2Ef6yWbkRU9mcmLihcPa9W0RupSGrRtCsHT9Z1CLr0lhhgET7Lg_Pl 60PGJzdpc9zr5QbPZmeA- Received: from [79.68.67.23] by web126205.mail.ne1.yahoo.com via HTTP; Wed, 05 Dec 2012 12:33:44 PST X-Rocket-MIMEInfo: 001.001, PiBGcm9tOiBEYW4gU2llbW9uIDxkYW5AY292ZXJmaXJlLmNvbT4KCgo.IFRoYW5rcyBmb3IgdGhlIGluZm8uIEkgZ3Vlc3MgSSdsbCBoYXZlIHRvIGtlZXAgZGlnZ2luZyB0byBmaWd1cmUgb3V0Cj4gd2hlcmUgdGhlIGxhdGVuY3kgY29tZXMgZnJvbS4KPiAKPiBJIGRpZCBhIGNvdXBsZSBtb3JlIGV4cGVyaW1lbnRzIHdoaWNoIGFwcGVhciB0byBjb25maXJtIHRoZSBsYXJnZSBhbW91bnQKPiBvZiBwZXItcGFja2V0IG92ZXJoZWFkOgo.IGh0dHA6Ly93d3cuY292ZXJmaXJlLmNvbS9hcmNoaXZlcy8yMDEyLzEBMAEBAQE- X-Mailer: YahooMailWebService/0.8.128.478 References: <20121123221842.GD2829@linux.vnet.ibm.com> <20121128172058.GB2474@linux.vnet.ibm.com> <20121202230635.GA16359@linux.vnet.ibm.com> <87obib5qf8.fsf@toke.dk> <1354550303.24281.103.camel@shinybook.infradead.org> <1354590837.29387.9.camel@ganymede.home> <1354613026.72238.YahooMailNeo@web126202.mail.ne1.yahoo.com> <1354678874.29387.12.camel@ganymede.home> Message-ID: <1354739624.4431.YahooMailNeo@web126205.mail.ne1.yahoo.com> Date: Wed, 5 Dec 2012 12:33:44 -0800 (PST) From: Alex Burr To: Dan Siemon In-Reply-To: <1354678874.29387.12.camel@ganymede.home> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable Cc: "codel@lists.bufferbloat.net" , "cerowrt-devel@lists.bufferbloat.net" , bloat Subject: Re: [Bloat] [Codel] [Cerowrt-devel] FQ_Codel lwn draft article review X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list Reply-To: Alex Burr List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 05 Dec 2012 20:33:49 -0000 > From: Dan Siemon =0A=0A=0A> Thanks for the info. I gue= ss I'll have to keep digging to figure out=0A> where the latency comes from= .=0A> =0A> I did a couple more experiments which appear to confirm the larg= e amount=0A> of per-packet overhead:=0A> http://www.coverfire.com/archives/= 2012/12/04/per-packet-overhead-on-vdsl2-2/=0A>=0A=0AIt almost looks like yo= u're being limited to 5k packets/sec. Now, I know that some devices will on= ly support a certain=A0 packet rate, and it's not as stupid as it sounds be= cause it's fairly rare to want to send max rate of solely minimum size pack= ets. But I wouldn't expect it here, because I would expect a VDSL2 device t= o work with 100Mbps down, 50Mbps up, even if your contract and line only su= pport much less. And the device would need to support more than 5k packets/= sec to get 50Mbps, even at the biggest packet size. I guess you might be ab= le to tell by plotting packet rate against packet size with more values of = packet size: if it's a rate limit, there will be a sharp corner, whereas if= it's overhead, there will should be more of a curve. The figure for the 75= byte payload suggests a curve.=0A=0APTM-TC has a minimum overhead of 2 byte= s/packet, IIRC. (I'm not counting the 65/64 cell overhead, because that is = not (in a good implementation) aligned to packet boundaries and is therefor= e better thought of as a 1/65 tax on your line rate). I'm not optimistic a= bout tuning shapers based on these details, however, as unlike ATM/AAL5, im= plementations are allowed to insert any amount of padding between packets, = so the per packet overhead is not predictable from the standard. There are = also nonstandard framing implementations. =0A=0A=0AAlex