[netperf-talk] Issues using parallel sessions of netperf

[Rick Jones]

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?

happy benchmarking,

rick jones

> 
> Thanks,
> Srikanth
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