From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-22-ewr.dyndns.com (mxout-021-ewr.mailhop.org [216.146.33.21]) by lists.bufferbloat.net (Postfix) with ESMTP id C47162E0271 for ; Tue, 15 Mar 2011 15:42:58 -0700 (PDT) Received: from scan-22-ewr.mailhop.org (scan-22-ewr.local [10.0.141.244]) by mail-22-ewr.dyndns.com (Postfix) with ESMTP id 500012E2EF for ; Tue, 15 Mar 2011 22:42:56 +0000 (UTC) X-Spam-Score: 0.0 () X-Mail-Handler: MailHop by DynDNS X-Originating-IP: 76.74.103.46 Received: from mail.vyatta.com (mail.vyatta.com [76.74.103.46]) by mail-22-ewr.dyndns.com (Postfix) with ESMTP id 9D9C7303D3 for ; Tue, 15 Mar 2011 22:42:51 +0000 (UTC) Received: from localhost (localhost.localdomain [127.0.0.1]) by mail.vyatta.com (Postfix) with ESMTP id ED3681829442; Tue, 15 Mar 2011 15:42:50 -0700 (PDT) X-Virus-Scanned: amavisd-new at tahiti.vyatta.com Received: from mail.vyatta.com ([127.0.0.1]) by localhost (mail.vyatta.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 18pbj4K6M5E3; Tue, 15 Mar 2011 15:42:50 -0700 (PDT) Received: from nehalam (pool-74-107-135-205.ptldor.fios.verizon.net [74.107.135.205]) by mail.vyatta.com (Postfix) with ESMTPSA id EBDA71829151; Tue, 15 Mar 2011 15:42:49 -0700 (PDT) Date: Tue, 15 Mar 2011 15:42:48 -0700 From: Stephen Hemminger To: Jonathan Morton Message-ID: <20110315154248.7d7fec3a@nehalam> In-Reply-To: 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> <219C7840-ED79-49EA-929D-96C5A6200401@gmail.com> <20110315151946.31e86b46@nehalam> <1300228592.2087.2191.camel@tardy> Organization: Vyatta X-Mailer: Claws Mail 3.7.6 (GTK+ 2.22.0; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII 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 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 22:42:59 -0000 On Wed, 16 Mar 2011 00:40:28 +0200 Jonathan Morton wrote: > > On 16 Mar, 2011, at 12:36 am, Rick Jones wrote: > > > Back and forth synchronization between driver and device is > > doubleplusungood. Being able to remove a packet on the tx queue already > > made known to the NIC sounds like it could become a rathole. If you are > > lucky, you *might* have a "valid/invalid" bit in a packet descriptor > > that the driver could hope to set before the NIC had pulled-in a copy > > across the I/O bus. > > Since this would be on the order of a second after submission, this seems unlikely then. > > The even better solution would be if the hardware timed-out an old packet by itself after about 1 second. Does this happen already? If not, can it? > > - Jonathan The real problem was the IEEE 802 design that does retransmit at link level and therefore ends up being outside of control of software.