Is a client robot an OS thread?

Alex Rousskov rousskov at
Mon Sep 9 15:07:08 UTC 2013

On 09/08/2013 07:40 PM, Alberto Klocker wrote:

> We run tests on a 10 Gb network environment with Polygraph as one of
> the benchmarking tools but have found we are hitting 100% CPU usage
> on both the poly-client and poly-server which would indicate we need
> to spread the processes and systems out.

Yes, you must run multiple Polygraph client and server processes to test
at 10Gb speeds [without using huge responses].

> How well does the reporting engine handle log files from multiple sources? 

Reporter and lx handle them well because Polygraph had to merge logs
from different _hosts_ from the early days of first cache-offs.

The primary problem with the SMP test setup is in IP address management
and configuration. In our SMP tests, we usually:

- create all IP aliases before the test using polygraph-aka;

- use --fake-hosts to tell each Polygraph process which local IP aliases
it should use; and

- fool Polygraph into thinking that is running on multiple hosts to make
sure each client process generates appropriate load (in reality, each
host is a CPU core).

We are working on removing the need for above hacks in future Polygraph

The above may not be relevant/important if your workloads do not use PGL
Benches and related features.

> Say I were to script a system that launches two or three instances of
> the client and server, will the reporting engine be capable of
> combining the results into one report?

Yes. Just give polygraph-reporter all the client-side and all the
server-side logs at once.

> Would it be better I write something that "merges" the results together?

No, and merging statistics correctly is actually not as easy as it may seem.

> I'm curious to see what others have done to ramp Polygraph up above its single core limits.

Please see the above notes. We are working on publishing our 10Gb
results which will allow us to share more details of our setup.



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