Re: [Xenomai-help] rt_queue_write error: "Cannot allocate memory "; bug or feature ?

[Philippe Gerum <rpm@xenomai.org>]

Roderik.Wildenburg@domain.hid wrote:
>> No more than one block is allocated at any given time in your example.
>> This is expected due to the priority scheme your test 
>> undergoes. In any
>> case, 282 bytes (+ a few bytes message header) should grab 
>> one 512-byte
>> buffer here. For anything below the size of a logical page (4k in
>> 2.3.x), the allocator picks the next power of 2 greater or 
>> equal to the
>> requested size.
> 
> Is it possible that a allocated block remembers the size he is allocated
> for 
> and that the block is just usable for this size even after the block is
> freed ?
>

The block will belong to a 512-byte pool until all the blocks from the
same pool are free, in which case the entire page the pool sits on will
be moved to a free page list, and recycled for blocks of any size.

>> What if you don't set any limit to the queue elements, i.e. passing
>> Q_UNLIMITED instead of 10. Does this change the behaviour?
>>
> 
> This does not help. What helps is increasing the queue size to e.g. 
> MAXLEN*100 = 200000
> (rt_queue_create(&qtest1q, "qtest1q", MAXLEN*100, Q_UNLIMITED, Q_FIFO))
> 
> Could you please try to run my example on your machine, or are you
> shure, that this
> problem is specific to our platform ? Thank you for your help !

This is likely not a platform specific issue. You may want to run your
small test on v2.4-rc6 on your side.

> 
> Best regards
> Roderik 
> 
> MAN Roland Druckmaschinen AG
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> 


-- 
Philippe.