From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-11-ewr.dyndns.com (mxout-069-ewr.mailhop.org [216.146.33.69]) by lists.bufferbloat.net (Postfix) with ESMTP id A73D62E0392 for ; Tue, 15 Mar 2011 14:32:03 -0700 (PDT) Received: from scan-11-ewr.mailhop.org (scan-11-ewr.local [10.0.141.229]) by mail-11-ewr.dyndns.com (Postfix) with ESMTP id E912692A263 for ; Tue, 15 Mar 2011 21:32:02 +0000 (UTC) X-Spam-Score: -4.0 (----) X-Mail-Handler: MailHop by DynDNS X-Originating-IP: 15.201.24.20 Received: from g4t0017.houston.hp.com (g4t0017.houston.hp.com [15.201.24.20]) by mail-11-ewr.dyndns.com (Postfix) with ESMTP id 9FF9E92A153 for ; Tue, 15 Mar 2011 21:32:02 +0000 (UTC) Received: from g4t0018.houston.hp.com (g4t0018.houston.hp.com [16.234.32.27]) by g4t0017.houston.hp.com (Postfix) with ESMTP id 38A8D387DE; Tue, 15 Mar 2011 21:32:02 +0000 (UTC) Received: from [16.89.244.213] (tardy.cup.hp.com [16.89.244.213]) by g4t0018.houston.hp.com (Postfix) with ESMTP id CFF1810187; Tue, 15 Mar 2011 21:32:01 +0000 (UTC) From: Rick Jones To: "John W. Linville" In-Reply-To: <20110315205146.GF2542@tuxdriver.com> References: <4D7F4121.40307@freedesktop.org> <20110315175942.GA10064@goldfish> <1300212877.2087.2155.camel@tardy> <20110315183111.GB2542@tuxdriver.com> <29B06777-CC5F-4802-8727-B04F58CDA9E3@gmail.com> <20110315205146.GF2542@tuxdriver.com> Content-Type: text/plain; charset="UTF-8" Date: Tue, 15 Mar 2011 14:31:59 -0700 Message-ID: <1300224719.2087.2173.camel@tardy> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Cc: bloat@lists.bufferbloat.net Subject: Re: [Bloat] Random idea in reaction to all the discussion of TCP flavours - timestamps? X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list Reply-To: rick.jones2@hp.com List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 15 Mar 2011 21:32:04 -0000 On Tue, 2011-03-15 at 16:51 -0400, John W. Linville wrote: > On Tue, Mar 15, 2011 at 09:40:06PM +0200, Jonathan Morton wrote: > > > > On 15 Mar, 2011, at 8:31 pm, John W. Linville wrote: > > > > > If you don't throttle _both_ > > > the _enqueue_ and the _dequeue_, then you could be keeping a nice, > > > near-empty tx queue on the host and still have a long, bloated queue > > > building at the device. > > > > Don't devices at least let you query how full their queue is? > > I suppose it depends on what you mean? Presumably drivers know that, > or at least can figure it out. The accuracy of that might depend on > the exact mechanism, how often the tx rings are replinished, etc. > > However, I'm not aware of any API that would let something in the > stack (e.g. a qdisc) query the device driver for the current device > queue depth. At least, I don't think Linux has one -- do other > kernels/stacks provide that? HP-UX's lanadmin (and I presume the nwmgr command in 11.31) command will display the "classic" interface MIB stats, which includes the outbound queue length. What it does (or should do) for that statistic in the face of a multi-queue device I've no idea :) rick jones