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. Reminds me of TLSF - if I only had the time... :)

When allocating 4K, only 4K are allocated.

I think the problem could rather be that you are running switchtest on a
multi-cpu system, in which same the number of cpu tasks created is 6 by cpu.


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