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 08:46:12 +0200 Message-ID: <4A9388B4.8030401@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> <4A931ED3.1090206@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Christoph Lameter , Sridhar Samudrala , Nivedita Singhvi , netdev@vger.kernel.org To: unlisted-recipients:; (no To-header on input) Return-path: Received: from gw1.cosmosbay.com ([212.99.114.194]:50503 "EHLO gw1.cosmosbay.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754356AbZHYGqR (ORCPT ); Tue, 25 Aug 2009 02:46:17 -0400 In-Reply-To: <4A931ED3.1090206@gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: Eric Dumazet a =E9crit : > Christoph Lameter a =E9crit : >> On Mon, 17 Aug 2009, Sridhar Samudrala wrote: >> >>> On Mon, 2009-08-17 at 18:13 -0400, Christoph Lameter wrote: >>>> On Mon, 17 Aug 2009, Sridhar Samudrala wrote: >>>> >>>>> What about ethtool -S ? Does it report any errors? >>>> Neither. This is is a broadcom bnx2 NIC. >>> Are you sure the packets are dropped at the sender? >> Yes I am sending 400k messages from the app and the receiver only ge= ts >> 341k @300 byte (which is the line rate). There is no way that the 40= 0k get >> over the line. Also if I reduce SO_SNDBUF then both receiver and >> sender get down to 341k. >> >> I added the output of ethtool -S at the end. >> >> The mcast tool can be had from http://gentwo.org/ll or from my direc= tory >> on www.kernel.org. >> >=20 > # gcc -v > Using built-in specs. > Target: i686-pc-linux-gnu > Configured with: ../gcc-4.4.1/configure --enable-languages=3Dc,c++ --= prefix=3D/usr > Thread model: posix > gcc version 4.4.1 (GCC) > # pwd > /opt/src/lldiag-0.14 > # make > gcc -Wall -omcast mcast.c -lrt -lm > mcast.c: In function =91set_ip=92: > mcast.c:121: warning: implicit declaration of function =91htons=92 > mcast.c: In function =91build_pattern_array=92: > mcast.c:168: warning: implicit declaration of function =91htonl=92 > /tmp/cc4sYCDr.o: In function `lock': > mcast.c:(.text+0xcad): undefined reference to `__sync_fetch_and_add_4= ' > collect2: ld returned 1 exit status > make: *** [mcast] Error 1 >=20 >=20 > I have no idea where is defined sync_fetch_and_add >=20 Doh... Dont bother, I had to add "-march=3Di686" to CFLAGS to get "xadd" suppo= rt