From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-we0-f171.google.com (mail-we0-f171.google.com [74.125.82.171]) (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 F3398202230 for ; Sun, 17 Jun 2012 20:21:43 -0700 (PDT) Received: by wejx9 with SMTP id x9so6724109wej.16 for ; Sun, 17 Jun 2012 20:21:42 -0700 (PDT) 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=FtOzT4MbGY71dL7TaphvEWQG7Y5WYEMLcdS/DxiH5SI=; b=NewPEcJ2YcjnK90qrpeMAsLoJEmNQiHn6enYCWQdM3qa/qSdbKUsDsPjqanI8zX6sX 9nPWQGvPvsKY5PraFqeerkPZqVh00HrLwf8kEcpuWcd6+peLQzxpLotbOMTnWBhdcFTI 1wef9pf32bdZzzPu/8h+VmPNTV1s1hPUQi1tSV42P5nlrog6VtJ2D4m9VuI1ixY/f1nS vKpUSn2mmsYZmDz+DNjWUkwQYfxTkAL5zHSW/3awdhmz3WMMfNe2EDlYaUr1CV3u0nwq wVdhaHu8Y3gUBNdEVvjixWH40czZYp46y+8VsAx7lJa+r/qgtAGzRvx5SNJ1KSeofgy7 SQ+A== MIME-Version: 1.0 Received: by 10.180.88.194 with SMTP id bi2mr20563499wib.20.1339989702007; Sun, 17 Jun 2012 20:21:42 -0700 (PDT) Received: by 10.223.103.199 with HTTP; Sun, 17 Jun 2012 20:21:41 -0700 (PDT) In-Reply-To: <1339989030.7491.328.camel@edumazet-glaptop> References: <1339972217-19159-1-git-send-email-dave.taht@bufferbloat.net> <1339985869.7491.262.camel@edumazet-glaptop> <1339989030.7491.328.camel@edumazet-glaptop> Date: Sun, 17 Jun 2012 23:21:41 -0400 Message-ID: From: Dave Taht To: Eric Dumazet Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: codel@lists.bufferbloat.net, =?ISO-8859-1?Q?Dave_T=E4ht?= Subject: Re: [Codel] [RFC PATCH] Codel: Enable packet drop with ECN-marked packets on a threshold X-BeenThere: codel@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: CoDel AQM discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 18 Jun 2012 03:21:44 -0000 On Sun, Jun 17, 2012 at 11:10 PM, Eric Dumazet wro= te: > On Sun, 2012-06-17 at 22:40 -0400, Dave Taht wrote: > >> (side note, I noticed fq_codel defaulted to 10k packets which is >> rather excessive for tiny routers - I just trimmed that down >> significantly for cerowrt and the upcoming 3.3.8-4 release has the rfc >> patch in it) >> >> And apologies for not seeing this long ago, > > 10k packets is too small to absorb a burst of 64bytes packets on 10Gb > links. Whole CoDel point is to accept packets at enqueue and drop them > at dequeue _if_ sejourn time too big. Number of packets should be > irrelevant. I agree the setting is good for 10GigE. 40GigE is coming up. 100GigE is being specified... > If you don't know how much packet can be sent on wire per unit of time, > just set a reasonable big limit. > > 1000 packets limit is not reasonable, while 10k is. > > linux average machines have more ram than tiny routers, dont assume we > release specialized code. It should be generic enough, granted it can be > easily tuned. I don't have a problem with the limit being set to sane values for modern systems. I note that for 10GigE we are also setting target, interval at lower values manually already, so setting that value additionally seems less work than requiring that systems running at GigE and below set it - systems that already have a pretty standard 1000 packet limit baked into their PFIFO_FAST assumptions. An overall better no knobs approach would be to be able to set the limit based on the observed hard or soft line rate of the interface. That said, so long as the need for setting a lower limit in fq_codel is well documented for smaller systems like tiny routers I don't have a problem with it. A sane limit can be calculated for soft-limited interfaces on devices with memory constraints as well > --=20 Dave T=E4ht SKYPE: davetaht http://ronsravings.blogspot.com/