Max messages in Message Queue

Samuel Bitton S.Bitton at sstl.co.uk
Tue Jun 16 08:00:29 UTC 2009


> On Tue, Jun 16, 2009 at 09:45, Aleix Conchillo Flaqué<aconchillo at ice.csic.es> wrote:
>> On Tue, Jun 16, 2009 at 09:20, Samuel Bitton<S.Bitton at sstl.co.uk> wrote:
>>> It cannot be too many queues as I can create the queue ok with 100
>>> messages in it.
>>> Note that I get the error when I call create with 500 messages.
>>> Also note that I don't think it is a memory issue as for 100 messages
>>> the message size is set to 33 bytes and for the 500 messages case, I set
>>> the message size to 5 bytes only. So in theory this would require as
>>> much memory (unless RTEMS uses a lot of overhead on a per message
>>> bases).
>>>
>>> So to me there is a limiting factor for the number of messages per
>>> queue?
>>>
>>
>> I'm not sure if this will be the problem, but if you are running 4.7
>> or older you might need to setup CONFIGURE_MEMORY_OVERHEAD which adds
>> space in the workspace for message queue buffers. Buffers are not
>> taken into account when reserving memory for message queues.
>>
>
> I forgot to mention:
>
> #define CONFIGURE_MEMORY_OVERHEAD 128
>
> would reserve 128Kbytes.
>
> For new RTEMS versions I think you need to use CONFIGURE_MESSAGE_BUFFER_MEMORY.
>
> Aleix

That was it! Many thanks Aleix.

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