RTEMS Message Queue Behaviour

[Aleix Conchillo Flaqué]

A while ago I experienced strange problems with queues until I
configured the memory for them. In 4.6.6 CONFIGURE_MEMORY_OVERHEAD
defines the number of  kbytes necessary to fit your queue messages and
CONFIGURE_MESSAGE_BUFFER_MEMORY for newer RTEMS versions. Buffers are
not taken into account when reserving memory for message queues.

Hope it helps,

Aleix

On Fri, Apr 9, 2010 at 11:56, Jamie Bowman
<jamie.bowman at steepestascent.com> wrote:
> All
>
>
>
> I am experiencing some strange behaviour with RTEMS message queues, although
> I suspect the problem may more to be with the main configuration of the
> application.
>
>
>
> I have a multi-threaded system, with a central logging thread. Information
> is sent from each thread to the logging thread via a single logging thread
> message queue. At the moment the logging thread simply uses a printf to
> output the messages it receives. The behaviour we are seeing though is that
> the logging thread is in a certain instances reading the messages out of the
> queue in the wrong order and it also seems that some messages are going
> missing all together. Monitoring the return of the rtems_message_queue_send
> does not seem to reveal any issues with RTEMS_SUCCESSFUL returned every
> time. An example of what I am seeing is as follows:
>
>
>
> Sent: Message 1
>
> Sent: Message 2
>
> Sent: Message 3
>
> Sent: Message 4
>
> Sent: Message 5
>
> Sent: Message 6
>
> Sent: Message 7
>
>
>
>             LOGGING THREAD
>
> Read: Message 1
>
> Read: Message 2
>
> Read: Message 4
>
> Read: Message 3
>
> Read: Message 5
>
>
>
> Messages 3 and 4 are out of order and 6 and 7 never seem to get through.
>
>
>
> Does anyone have any ideas as to why this may be happening? I am using RTEMS
> 4.8.1.
>
>
>
> Kind regards
>
>
>
>             Jamie
>
>
>
>
>
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>