Max messages in Message Queue

[Aleix Conchillo Flaqué]

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