From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-03-iad.dyndns.com (mxout-098-iad.mailhop.org [216.146.32.98]) by lists.bufferbloat.net (Postfix) with ESMTP id 892912E098A for ; Tue, 15 Mar 2011 18:02:52 -0700 (PDT) Received: from scan-01-iad.mailhop.org (scan-01-iad.local [10.150.0.206]) by mail-03-iad.dyndns.com (Postfix) with ESMTP id 25187834AC0 for ; Wed, 16 Mar 2011 01:02:54 +0000 (UTC) X-Spam-Score: -4.0 (----) X-Mail-Handler: MailHop by DynDNS X-Originating-IP: 15.193.32.61 Received: from g6t0184.atlanta.hp.com (g6t0184.atlanta.hp.com [15.193.32.61]) by mail-03-iad.dyndns.com (Postfix) with ESMTP id CF47C834A92 for ; Wed, 16 Mar 2011 01:02:53 +0000 (UTC) Received: from g5t0030.atlanta.hp.com (g5t0030.atlanta.hp.com [16.228.8.142]) by g6t0184.atlanta.hp.com (Postfix) with ESMTP id D8ACAC34A; Wed, 16 Mar 2011 01:02:50 +0000 (UTC) Received: from [16.89.244.213] (tardy.cup.hp.com [16.89.244.213]) by g5t0030.atlanta.hp.com (Postfix) with ESMTP id 7321414073; Wed, 16 Mar 2011 01:02:50 +0000 (UTC) From: Rick Jones To: "John W. Linville" In-Reply-To: <20110316003234.GC28663@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> <1300224719.2087.2173.camel@tardy> <20110316003234.GC28663@tuxdriver.com> Content-Type: text/plain; charset="UTF-8" Date: Tue, 15 Mar 2011 18:02:47 -0700 Message-ID: <1300237367.2087.2238.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: Wed, 16 Mar 2011 01:02:52 -0000 On Tue, 2011-03-15 at 20:32 -0400, John W. Linville wrote: > On Tue, Mar 15, 2011 at 02:31:59PM -0700, Rick Jones wrote: > > 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 :) > > But that is capacity, right? Not current occupancy? I thought that > was the outcome of an earlier thread? No, HP-UX shows current occupancy on its interfaces. I think it is Cisco which shows capacity - at least that is my recollection of one of the other discussions. rick