Jan Kiszka wrote:
> Philippe Gerum wrote:
>> Jan Kiszka wrote:
>>> Philippe Gerum wrote:
>>>> Jan Kiszka wrote:
>>>>> Gilles Chanteperdrix wrote:
>>>>>> Jan Kiszka wrote:
>>>>>>> Gilles Chanteperdrix wrote:
>>>>>>>> Jan Kiszka wrote:
>>>>>>>>> Hi Gilles,
>>>>>>>>> how much XENO_OPT_SYS_STACKPOOLSZ do I need to run switchtest for
>>>>>>>>> default settings? At least on x86-64, the default 32K is not enough.
>>>>>>>>> Unless we talk about GB ;), maybe it makes sense to adjust the default
>>>>>>>>> size accordingly.
>>>>>>>> It depends on the arguments you pass to switchtest.
>>>>>>> None, ie. the default settings.
>>>>>> Then 6 kernel-space tasks are created. Since switchtest is not the
>>>>> 6*4 is 20k... Ah, the well-known allocator overhead, I guess. Will try
>>>>> with >= 40k.
>>>> Actually, it is not really an overhead, but rather the fact that it wants 
>>>> at
>>>> least two initially free pages per heap.
>>> That would make 22K. The problem is that the management overhead is
>>> rounded up to another full page, requiring a 8K allocation per 4K
>>> request.
>> Nope. An individual 4k request is going to pull 8 x 512 bytes pages from the
>> stack pool, not more.
> Yeah, I see. The only "overhead" here was already paid via the pagemap.
>>  Reminds me of TLSF - if I only had the time... :)
>> It looks like working properly for -solo.
> I think to remember your concerns were more about missing fragmentation,
> size overhead and performance comparisons. A working version for
> standard Xenomai was already available at that time (maybe not for all
> archs, but that is surely quickly fixed).

Locking and init fixes went to TLSF 2.4.4 in the recent months, so we would have
needed those anyway. It's quite late to merge TLSF in Xenomai 2.5, but I would
have no objection to make it the base allocator of the 3.x series. We would have
to extend it with:

- support for a few callouts, such as the validity checking function used in
- shared memory export (this is quite allocator agnostic in fact)
- detailed error codes in xnheap_test_and_free/xnheap_free

> Jan


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