Re: [certi-dev] Maximum amount of federates

[Timi Tuohenmaa]

2014-10-21 17:55 GMT+03:00 Eric Noulard <address@hidden>:
>
>
> 2014-10-21 13:01 GMT+02:00 Timi Tuohenmaa <address@hidden>:
>>
>> Hi,
>>
>> Yes! This seemed to be the issue. I added
>> ADD_DEFINITIONS(-DFD_SETSIZE=128) to CMakeLists.txt and it seemed to
>> fix the problem.
>
>
> Nice, thank you for testing.

It was obviously for selfish reasons ;)

>>
>> I suppose we will compile CERTI with 256 just in case... We'll see how
>> much performance issues that many federates will cause, but 64 is not
>> really a problem apart from this stupid Winsock limitation.
>
>
> On modern host I don't you'll hit the performance wall very soon
> RTIG as a central point may appear as a kind of bottleneck handling that
> much
> connection (100+) but in fact the limiting factor is certainly the network
> throughput, i.e.
> how many messages (per second) each federate generate.
>
> So handling a 100+ federate shouldn't be a problem unless some if not all of
> them
> tries to generate 200Hz messages...

We'll see how it goes. Some of the data needs to be updated quite often.

>>
>> I don't know if that limit should be risen by default CERTI, but maybe
>> it should be added as option in CMake.
>
>
>
> An option would be good  I think, our average user do not go further
> than 20+ federates.

That's quite likely when simulation does not need to scale (using same
federates all over again).

>>
>> But very much thank you. I think it would have taken quite much time
>> to realise that issue is not in CERTI but Winsock.
>
>
> You're welcome.
> I have always in mind that I'm convinced that CERTI cannot always be the
> culprit :-)
>
> More seriously, 64 didn't look like any limit/constant I know in CERTI
> source code
> and I did never hit such a limit on my usual unix environment.
>
> I'm curious why you need more than 64 federates, could you tell us a bit
> more about that?

We run real time training simulator and different parts of the
simulation are built
to different programs. When we add more student stations we need to
have multiple
new federates. We could combine some of them to a single program, but currently
there has been no need to do it.

That's why I have been somewhat active to fix some issues in CERTI and offer
fixes to bugs I have found.

-Timi

>
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