Hi Martin, For me, with traffic control and the txqueuelen set to zero, the iperf client does not seem to get the ENOBUFS and the tx rate reporting is that per the -b (offered load). The iperf server is receiving at the qdisc setting (shaped rate) vs the offered load (-b). So it does look like there is some interplay between ENOBUFS, qdiscs, and the txqueuelen that affects tx rate reporting.
Bob -----Original Message----- From: Martin T [mailto:m4rtn...@gmail.com] Sent: Thursday, September 25, 2014 4:10 PM To: Bob (Robert) McMahon Cc: Marc Herbert; Andrew Gallatin; iperf-users@lists.sourceforge.net Subject: Re: [Iperf-users] Iperf client sends out less UDP traffic than determined with "-b" flag Bob, I see, thanks! As a last thing, I played around with qdisc buffer and kernel NIC driver circular-buffer size. Unfortunately I wasn't able to reproduce the results I saw on this virtual-machine. Even with no qdisc buffer("ip link set dev eth0 txqueuelen 0") and lowest NIC driver buffer supported on my tg3(ver 3.2.0-4-amd64) driver for my Broadcom BCM5721 chipset, the Iperf client sent out as much UDP traffic as determined with "-b" option: root@3:~# ip link show dev eth0 2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT link/ether 00:1d:09:f0:92:ab brd ff:ff:ff:ff:ff:ff root@3:~# ethtool -g eth0 Ring parameters for eth0: Pre-set maximums: RX: 511 RX Mini: 0 RX Jumbo: 0 TX: 511 Current hardware settings: RX: 0 RX Mini: 0 RX Jumbo: 0 TX: 55 root@3:~# iperf -c 192.0.2.1 -fm -t 10 -u -b 800m ------------------------------------------------------------ Client connecting to 192.0.2.1, UDP port 5001 Sending 1470 byte datagrams UDP buffer size: 0.22 MByte (default) ------------------------------------------------------------ [ 3] local 192.168.1.45 port 44172 connected with 192.0.2.1 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.0 sec 962 MBytes 807 Mbits/sec [ 3] Sent 686293 datagrams [ 3] WARNING: did not receive ack of last datagram after 10 tries. root@3:~# Has anyone managed to reproduce the behavior described in my initial e-mail with decreasing the Tx buffers sizes on (virtual-)machine where the Iperf client is running? regards, Martin ------------------------------------------------------------------------------ Meet PCI DSS 3.0 Compliance Requirements with EventLog Analyzer Achieve PCI DSS 3.0 Compliant Status with Out-of-the-box PCI DSS Reports Are you Audit-Ready for PCI DSS 3.0 Compliance? Download White paper Comply to PCI DSS 3.0 Requirement 10 and 11.5 with EventLog Analyzer http://pubads.g.doubleclick.net/gampad/clk?id=154622311&iu=/4140/ostg.clktrk _______________________________________________ Iperf-users mailing list Iperf-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/iperf-users
