[netperf-talk] Issues using parallel sessions of netperf

[Rick Jones]

On Wed, 2011-04-13 at 16:57 -0400, Srikanth Sundaresan wrote:
> 
> On 04/13/2011 04:54 PM, Rick Jones wrote:
> > On Wed, 2011-04-13 at 16:31 -0400, Srikanth Sundaresan wrote:
> >> Hi,
> >> We are a group from Georgia Tech working on building a benchmarking
> >> suite for home broadband internet. I've been testing netperf out as the
> >> throughput tool.
> >> In order to fully saturate the link, I'm running 3 netperf sessions
> >> simultaneously. However, this causes 1 or two of the sessions to fail
> >> with the following error:
> >>
> >> send_tcp_maerts: data recv error: Interrupted system call.
> >> The output also has the following error: len was -1
> >>
> >> This only seems to occur on the TCP_MAERTS test; the TCP_STREAM test
> >> seems to work fine (caveat: this is from a few dozen runs). Also, if I
> >> run only 1 session, TCP_MAERTS works.
> >>
> >> Here's a sample output:
> >> bin/netperf -l30 -P0 -fk -t TCP_MAERTS -p14536 143.215.129.122
> >> bin/netperf -l30 -P0 -fk -t TCP_MAERTS -p14536 143.215.129.122
> >> bin/netperf -l30 -P0 -fk -t TCP_MAERTS -p14536 143.215.129.122
> >> send_tcp_maerts: data recv error: Interrupted system call
> >>
> >> In this example, one session failed. I tried opening 3 instances of
> >> netserver on the server on 3 ports, but the same error occurred.
> >>
> >> I'm using netperf 2.4.5 on Linux 2.6.32. Please let me know if you need
> >> more information. Any help would be greatly appreciated.
> > 
> > My initial guess is that the end-of-test timer is firing when it was not
> > expected to - perhaps the rate of data flow through the broadband link
> > into the netperf(s) is such that the remote's close does not happen
> > before the watchdog timer pops?
> > 
> This testing is in an academic network (1Gbps connection between 2
> servers). I was able to replicate it on a broadband link (though I only
> ran the experiment a couple of times). Is there any more information
> that I can give you that might help in debugging the issue?

How much time passes before the error message(s) appear?

happy benchmarking,

rick jones