perfSONAR User Q&A and Other Discussion

[Brian Candler <>]

On 18/12/2014 19:39, Bruce A. Mah wrote:
> I wonder if one of the endpoints was moving rapidly relative to the
> other, or whether one of them was deployed close to a singularity and
> was suffering from relativistic time dilation.:-)
Nice theory, but I have found it's triggered by the -Z (--zerocopy) 
option on iperf3 with OSX. It can be replicated with standalone iperf3 
without bwctl.

Below shows the same test with and without -Z.  Note that the actual 
transfer is fast: it's just the OSX end records much lower throughput 
figures than the perfsonar end.

Regards,

Brian.

[Note: cov-client-1 / ::252 is the OSX end, and cov-perf-1 / ::254 is 
the Perfsonar PS Toolkit end]

cov-client-1:~ admin$ iperf3 -c cov-perf-1 -Z
Connecting to host cov-perf-1, port 5201
[  6] local 2001:db8:0:64::252 port 51972 connected to 2001:db8:0:2::254 
port 5201
[ ID] Interval           Transfer     Bandwidth
[  6]   0.00-1.00   sec  4.62 MBytes  38.8 Mbits/sec
[  6]   1.00-2.00   sec  2.12 MBytes  17.8 Mbits/sec
[  6]   2.00-3.00   sec  1.62 MBytes  13.6 Mbits/sec
[  6]   3.00-4.00   sec  1.75 MBytes  14.7 Mbits/sec
[  6]   4.00-5.00   sec  1.50 MBytes  12.6 Mbits/sec
[  6]   5.00-6.00   sec  1.62 MBytes  13.6 Mbits/sec
[  6]   6.00-7.00   sec  1.88 MBytes  15.7 Mbits/sec
[  6]   7.00-8.00   sec  1.38 MBytes  11.5 Mbits/sec
[  6]   8.00-9.00   sec  1.50 MBytes  12.6 Mbits/sec
[  6]   9.00-10.00  sec  1.62 MBytes  13.6 Mbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth
[  6]   0.00-10.00  sec  19.6 MBytes  16.5 Mbits/sec                  sender
[  6]   0.00-10.00  sec  1.05 GBytes   904 Mbits/sec                  
receiver

iperf Done.
cov-client-1:~ admin$ iperf3 -c cov-perf-1
Connecting to host cov-perf-1, port 5201
[  6] local 2001:db8:0:64::252 port 51974 connected to 2001:db8:0:2::254 
port 5201
[ ID] Interval           Transfer     Bandwidth
[  6]   0.00-1.00   sec  84.8 MBytes   712 Mbits/sec
[  6]   1.00-2.00   sec  84.8 MBytes   711 Mbits/sec
[  6]   2.00-3.00   sec   110 MBytes   927 Mbits/sec
[  6]   3.00-4.00   sec   111 MBytes   927 Mbits/sec
[  6]   4.00-5.00   sec   110 MBytes   925 Mbits/sec
[  6]   5.00-6.00   sec   110 MBytes   926 Mbits/sec
[  6]   6.00-7.00   sec   110 MBytes   926 Mbits/sec
[  6]   7.00-8.00   sec   111 MBytes   928 Mbits/sec
[  6]   8.00-9.00   sec   110 MBytes   925 Mbits/sec
[  6]   9.00-10.00  sec   110 MBytes   926 Mbits/sec
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth
[  6]   0.00-10.00  sec  1.03 GBytes   883 Mbits/sec                  sender
[  6]   0.00-10.00  sec  1.03 GBytes   883 Mbits/sec                  
receiver

iperf Done.