From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: UDP multicast packet loss not reported if TX ring overrun? Date: Tue, 25 Aug 2009 17:58:08 +0200 Message-ID: <4A940A10.60607@gmail.com> References: <4A89C026.4030402@us.ibm.com> <1250545839.25939.21.camel@w-sridhar.beaverton.ibm.com> <1250549034.25939.30.camel@w-sridhar.beaverton.ibm.com> <1250554332.25939.46.camel@w-sridhar.beaverton.ibm.com> <4A930DEF.5000008@gmail.com> <4A93EB9B.5020600@gmail.com> <4A9403F0.2060301@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Sridhar Samudrala , Nivedita Singhvi , netdev@vger.kernel.org, "David S. Miller" To: Christoph Lameter Return-path: Received: from gw1.cosmosbay.com ([212.99.114.194]:59973 "EHLO gw1.cosmosbay.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752936AbZHYP7K (ORCPT ); Tue, 25 Aug 2009 11:59:10 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: Christoph Lameter a =E9crit : > On Tue, 25 Aug 2009, Eric Dumazet wrote: >=20 >> Christoph Lameter a ?crit : >>> On Tue, 25 Aug 2009, Eric Dumazet wrote: >>> >>>> Please hold on, I would like to fully understand what's happening, >>>> and test the patch :) >>> Ok. It would be good if the drops would also be somehow noted by th= e UDP >>> subsystem (one should see something with netstat -su) and may be ev= en the >>> socket. I see a drops column in /proc/net/udp. rx_drops, tx_drops? >> This /proc/net/udp column is for rx_drops currently and was recently= added... >=20 > So lets rename it to rx_drops and then add tx_drops? >=20 It wont be very nice, because it'll add yet another 32bits counter in e= ach socket structure, for a unlikely use. While rx_drops can happen if application= is slow. Also, tx_drops might be done later and not noticed. Please read this old (and usefull) thread, with Alexey words... http://oss.sgi.com/archives/netdev/2002-10/msg00612.html http://oss.sgi.com/archives/netdev/2002-10/msg00617.html So I bet your best choice is to set IP_RECVERR, as mentioned in 2002 by= Jamal and Alexey :)