From mboxrd@z Thu Jan 1 00:00:00 1970 From: jamal Subject: Re: [PATCH] NET: Multiqueue network device support. Date: Tue, 12 Jun 2007 08:17:42 -0400 Message-ID: <1181650662.4060.72.camel@localhost> References: <1181082517.4062.31.camel@localhost> <4666CEB7.6030804@trash.net> <1181168020.4064.46.camel@localhost> <466D38CF.9060709@trash.net> <1181564611.4043.220.camel@localhost> <1181639998.29767.59.camel@johannes.berg> Reply-To: hadi@cyberus.ca Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Patrick McHardy , "Waskiewicz Jr, Peter P" , davem@davemloft.net, netdev@vger.kernel.org, jeff@garzik.org, "Kok, Auke-jan H" To: Johannes Berg Return-path: Received: from wx-out-0506.google.com ([66.249.82.227]:21695 "EHLO wx-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753070AbXFLMRs (ORCPT ); Tue, 12 Jun 2007 08:17:48 -0400 Received: by wx-out-0506.google.com with SMTP id t15so1768826wxc for ; Tue, 12 Jun 2007 05:17:47 -0700 (PDT) In-Reply-To: <1181639998.29767.59.camel@johannes.berg> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Tue, 2007-12-06 at 11:19 +0200, Johannes Berg wrote: > On Mon, 2007-06-11 at 08:23 -0400, jamal wrote: > > Sure. Packets stashed on the any DMA ring are considered "gone to the > > wire". That is a very valid assumption to make. > > Not at all! Packets could be on the DMA queue forever if you're feeding > out more packets. Heck, on most wireless hardware packets can even be > *expired* from the DMA queue and you get an indication that it was > impossible to send them. The spirit of the discussion you are quoting was much higher level than that. Yes what you describe can happen on any DMA (to hard-disk etc) A simpler example, if you tcpdump on an outgoing packet you see it on its way to the driver - it is accounted for as "gone"[1]. In any case, read the rest of the thread. cheers, jamal [1] Current Linux tcpdumping is not that accurate, but i dont wanna go into that discussion