[zeromq-dev] ZMQ_RATE

[Steven McCoy]

On 3 October 2011 11:18, Emmanuel TAUREL <taurel at esrf.fr> wrote:

>  On 03/10/2011 17:02, Steven McCoy wrote:
>
> On 3 October 2011 10:19, Emmanuel TAUREL <taurel at esrf.fr> wrote:
>
>> Hello all,
>>
>> I am experimenting PUB/SUB sockets with PGM protocol.
>> I am actually using with the ZMQ_RATE socket option.
>> My understanding of this parameter was that it is the maximum rate for
>> sending/receiving data and thus limits the network bandwidth used by PGM.
>> In my test, the publisher sends messages as fast as it can.
>> I have tried different value for the ZMQ_RATE parameter: 100 which means
>> 100 kbits/sec (the default) and 80000 which means 80Mbit/sec.
>> I capture network packets using wireshark. When I look at its IO graph
>> after the capture, there is no difference between the two runs.
>> During the PGM transmission, I always have a network usage close to 100
>> Mbit/sec which is my network bandwidth between the pub and sub hosts.
>>
>> Where is my error?
>> Do I have to understand that ZMQ_RATE limits the data rate in the
>> process but not on the network (meaning buffering required in case of
>> slow ZMQ_RATE)?
>>
>>
>  Correct but the differences are going to be only latent.
>
>  The default for ZMQ_RATE is now 40*1000, 40mbit/s, because you cannot
> really do any testing with 100kbit/s as it is way too slow.  This does
> suggest you are on an older version and you may wish to retry with at least
> 2.1.9.
>
>  You can compare with the local_thr and remote_thr performance test
> programs which work correctly.
>
>  There may be a problem with timer accuracy on your platform, you may try
> setting the environment variable PGM_TIMER to GETTIMEOFDAY, TSC, or CLOCK_GETTIME
> for different methods:
>
>
> http://code.google.com/p/openpgm/wiki/OpenPgmCReferenceRunWithTheseCapabilities
>
>
> Thank's for your answer.
> I am using zmq 3.
>
>
So this might be a regression on setting the rate limit on the PGM socket.
 I would suggest comparing operation with version 2.  I'm only looking at v2
for bug fixes and v4 for enhancements so additional awareness is required
for the v3 branch.

-- 
Steve-o
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