From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Lameter Subject: Re: UDP multicast packet loss not reported if TX ring overrun? Date: Wed, 26 Aug 2009 12:29:34 -0400 (EDT) Message-ID: References: <1251239734.3169.65.camel@w-sridhar.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: David Stevens , "David S. Miller" , Eric Dumazet , netdev@vger.kernel.org, netdev-owner@vger.kernel.org, niv@linux.vnet.ibm.com, sri@linux.vnet.ibm.com To: Sridhar Samudrala Return-path: Received: from smtp4.ultrahosting.com ([74.213.175.253]:40542 "EHLO smtp.ultrahosting.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751287AbZHZQaJ (ORCPT ); Wed, 26 Aug 2009 12:30:09 -0400 In-Reply-To: <1251239734.3169.65.camel@w-sridhar.beaverton.ibm.com> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 25 Aug 2009, Sridhar Samudrala wrote: > Could you check if the UDP packet losses you are seeing are accounted for in > qdisc drops with this patch. But i am not completely positive on this as this > case happens only if qdisc is deactivated. This does not work. qdisc drops are still not reported. They are reported for IP and UDP. Test tool crashes on first TX overrun: clameter@rd-strategy3-deb64:~$ ./mcast -n1 -r400000 Receiver: Listening to control channel 239.0.192.1 Receiver: Subscribing to 0 MC addresses 239.0.192-254.2-254 offset 0 origin 10.2.36.123 Sender: Sending 400000 msgs/ch/sec on 1 channels. Probe interval=0.001-1 sec. sendto: No buffer space available Socket Send error netstat reports exactly one packet loss: clameter@rd-strategy3-deb64:~$ netstat -su IcmpMsg: InType3: 1 OutType3: 1 Udp: 298 packets received 0 packets to unknown port received. 0 packet receive errors 7232136 packets sent SndbufErrors: 1 root@rd-strategy3-deb64:/home/clameter#tc -s qdisc show qdisc pfifo_fast 0: dev eth0 root bands 3 priomap 1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1 Sent 6208 bytes 64 pkt (dropped 0, overlimits 0 requeues 0) rate 0bit 0pps backlog 0b 0p requeues 0 SNMP report one drop: root@rd-strategy3-deb64:/home/clameter#cat /proc/net/snmp Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests OutDiscards OutNoRoutes ReasmTimeout ReasmReqds ReasmOKs ReasmFails FragOKs FragFails FragCreates Ip: 2 64 1114 0 0 0 0 0 1114 7232754 1 0 0 0 0 0 0 0 0 Icmp: InMsgs InErrors InDestUnreachs InTimeExcds InParmProbs InSrcQuenchs InRedirects InEchos InEchoReps InTimestamps InTimestampReps InAddrMasks InAddrMaskReps OutMsgs OutErrors OutDestUnreachs OutTimeExcds OutParmProbs OutSrcQuenchs OutRedirects OutEchos OutEchoReps OutTimestamps OutTimestampReps OutAddrMasks OutAddrMaskReps Icmp: 1 0 1 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 IcmpMsg: InType3 OutType3 IcmpMsg: 1 1 Tcp: RtoAlgorithm RtoMin RtoMax MaxConn ActiveOpens PassiveOpens AttemptFails EstabResets CurrEstab InSegs OutSegs RetransSegs InErrs OutRsts Tcp: 1 200 120000 -1 26 4 0 0 2 774 595 0 0 0 Udp: InDatagrams NoPorts InErrors OutDatagrams RcvbufErrors SndbufErrors Udp: 308 0 0 7232146 0 1 UdpLite: InDatagrams NoPorts InErrors OutDatagrams RcvbufErrors SndbufErrors UdpLite: 0 0 0 0 0 0