Created attachment 289793 [details] fix compat/delay.cpp:delay_loop() for delays of 1s and greater Trying to send UDP packets at low bandwidth will fail horribly and flood. An example, requesting a bandwidth of 1000 bits/s, sending 10 packets of 125 bytes, which should mean 1 packet per second, this is what I get: $ time iperf -u -c 10.0.0.254 -b1000 -l125 -n1250 ------------------------------------------------------------ Client connecting to 10.0.0.254, UDP port 5001 Sending 125 byte datagrams nanosleep failed: Invalid argument UDP buffer size: 120 KByte (default) ------------------------------------------------------------ nanosleep failed: Invalid argument [ 3] local 10.0.0.18 port 50674 connected with 10.0.0.254 port 5001 nanosleep failed: Invalid argument nanosleep failed: Invalid argument nanosleep failed: Invalid argument nanosleep failed: Invalid argument nanosleep failed: Invalid argument nanosleep failed: Invalid argument nanosleep failed: Invalid argument nanosleep failed: Invalid argument [ ID] Interval Transfer Bandwidth [ 3] 0.0- 0.0 sec 1.22 KBytes 119 Mbits/sec [ 3] Sent 10 datagrams [ 3] Server Report: [ 3] 0.0-3814.5 sec 1.22 KBytes 2.62 bits/sec 0.000 ms 0/ 9 (0%) [ 3] 0.0-3814.5 sec 1 datagrams received out-of-order real 0m0.021s user 0m0.003s sys 0m0.000s The problem is the function which is called to do the sleeping between packet sends. It's compat/delay.cpp:delay_loop() and it doesn't deal with usec>=1000000 (1 second) properly. It uses POSIX nanosleep(), which requires that the tv_nsec argument be lower than 1000 million, that is, that the seconds value be used appropriately and not just set to zero. As is, delay_loop will fail for usec > 999999. It doesn't sleep at all, causing a very high packet send rate. Steps to reproduce: 1. Set up an UDP iperf server on a remote machine: iperf -u -s -U 2. Send UDP packets at a low rate, e.g. for 10 packets (to limit amount of errors): iperf -u -c $server_ip -b1000 -l125 -n1250 3. See a bunch of errors and the actual rate is much higher. I am attaching a patch that fixes this and restores expected behavior: $ time ./src/iperf -u -c 10.0.0.254 -b1000 -l125 -n1250 ------------------------------------------------------------ Client connecting to 10.0.0.254, UDP port 5001 Sending 125 byte datagrams UDP buffer size: 120 KByte (default) ------------------------------------------------------------ [ 3] local 10.0.0.18 port 35078 connected with 10.0.0.254 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.0 sec 1.22 KBytes 1000 bits/sec [ 3] Sent 10 datagrams [ 3] Server Report: [ 3] 0.0-4130.0 sec 1.22 KBytes 2.42 bits/sec 0.006 ms 0/ 10 (0%) real 0m10.027s user 0m0.000s sys 0m0.010s Patch is made against upstream SVN trunk (r81), but it also applies perfectly against release 2.0.5. Upstream's last commit was a year ago, and they have stated in their site that they don't plan on updating 2.0x unless absolutely necessary, so IMHO it would be good to merge this patch into Portage. Changelog entry: 2011-10-14 Israel G. Lugo <israel.lugo@lugosys.com> * Fix delay_loop() for delays of 1s and greater. Was causing breakage when a low bandwidth limit was specified.
+ 06 Oct 2012; Sergey Popov <pinkbyte@gentoo.org> +iperf-2.0.5-r1.ebuild, + +files/iperf-fix-bandwidth-limit.patch: + Revision bump, add fix for bug #387129, bump to EAPI 4
