Re: [Xenomai-core] XENO_OPT_SYS_STACKPOOLSZ vs. switchtest

[Philippe Gerum <rpm@xenomai.org>]

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.

>> average use of Xenomai, and is supposed to be used only for validating
>> the context/FPU switches, I would not change XENO_OPT_SYS_STACKPOOL_SZ,
>> maybe only add a clear message when creation of kernel-space tasks fails.
> 
> Well, isn't the switchtest part of xeno-test? Would be unfortunate to
> require a kernel rebuild just for running the standard tests. I think we
> don't loose much by slightly increasing the stack to, say, 64K on 32 bit
> and 128K on 64 bit archs.
> 
> BTW, XNARCH_THREAD_STACKSZ for x86-64 equals the x86-32 bit value (4K)
> while I don't think the have they same demands (nor the same resource
> restrictions).
> 
> Jan
> 


-- 
Philippe.