From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarek Poplawski Subject: Re: [PATCH] af_packet: Don't use skb after dev_queue_xmit() Date: Mon, 18 Jan 2010 22:50:48 +0100 Message-ID: <20100118215048.GF3157@del.dom.local> References: <20100117221746.GA3161@del.dom.local> <4B53906B.2020608@majjas.com> <20100117230531.GC3161@del.dom.local> <4B539A0A.2000504@majjas.com> <20100118073018.GA6270@ff.dom.local> <4B548C6B.10607@majjas.com> <20100118204658.GC3157@del.dom.local> <4B54CB0D.5070604@majjas.com> <20100118130038.77a3adfb@nehalam> <4B54D1A4.2020609@majjas.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Stephen Hemminger , David Miller , akpm@linux-foundation.org, flyboy@gmail.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org To: Michael Breuer Return-path: Received: from mail-fx0-f225.google.com ([209.85.220.225]:63847 "EHLO mail-fx0-f225.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754434Ab0ARVuz (ORCPT ); Mon, 18 Jan 2010 16:50:55 -0500 Content-Disposition: inline In-Reply-To: <4B54D1A4.2020609@majjas.com> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, Jan 18, 2010 at 04:24:52PM -0500, Michael Breuer wrote: > On 1/18/2010 4:00 PM, Stephen Hemminger wrote: > >On Mon, 18 Jan 2010 15:56:45 -0500 > >Michael Breuer wrote: > > > >>>>2. The dropped tx packet (DHCP) is a bit harder to recreate, but it > >>>>still happens. > >>>> > >You might want to use tc filter rule to set priority of DHCP packets > >higher. This would cause them to be in a separate queue and eliminate > >the problem. > > > Ok - for fun, tried that - no change. Not sure I see why this might > be a factor. The packet loss happens when TX load is low and RX > high. > Also, packets only being dropped if traversing a router vs.to the > router itself. Keep in mind that pings to the router did not lose > packets, pings through the router lost packets. The router was not > under load (traffic is being generated from a device connected via > the 1Gb switch, not the wifi router), and tcpdump on the router > input port shows the pings to the router, but not the ones through > the router. > > One added note, when I just tried this, the test data ended while > the packet loss was occurring. The DHCPOFFER packet loss did not > clear until about a minute after the throughput abated. I really > think something is getting hosed, and I'd but some weird interaction > with the arp logic high on the list of suspects. Not sure what else > would be a factor when looking at the extra hop on the same subnet. Good point! Actually, IIRC, your setup might be a problem: you seem to have two switches on the path (I guess the router is a bridge for these wireless), so I wonder if it's not something between them. Jarek P.