[netperf-talk] Issues using parallel sessions of netperf

[Srikanth Sundaresan]

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?