[Xenomai] kernel equivalent of SIGXCPU

[Xenomai] kernel equivalent of SIGXCPU

[Michael Haberler]

I'm trying to trap scheduling violations through an exception handler

in user RT it's straightforward - use the SIGXCPU handler

is rthal_trap_catch() the way to go? 

or is it just evaluating the rt_task_wait_period() returns ? 

I'm a bit fuzzy as to the relation between these two - the manual says for rthal_trap_catch() '...uncontrolled exception or fault is caught at machine level.'; does this include scheduling overruns? it seems not to I guess

I have both in place but unsure atm what rthal_trap_catch() would buy me ontop

thanks in advance

- Michael

ps: I know that stuff is deprecating, it's all about a first-class funeral ;)

Re: [Xenomai] kernel equivalent of SIGXCPU

[Gilles Chanteperdrix]

On 05/22/2013 12:01 PM, Michael Haberler wrote:

> I'm trying to trap scheduling violations through an exception handler


How do you define "scheduling violations" ?

> 
> in user RT it's straightforward - use the SIGXCPU handler


No, SIGXCPU detect involuntary mode switches to secondary mode, if you
have the XNWARNSW bit set, it traps Linux system calls made by a thread
running in secondary mode.

> 
> is rthal_trap_catch() the way to go? 


rthal_trap_catch, allows to trap machine exceptions.

> 
> or is it just evaluating the rt_task_wait_period() returns ? 


rt_task_wait_period returns an error when an overrun happens, that is
when the timer ticks twice without the periodic thread having called
rt_task_wait_period.

> 
> I'm a bit fuzzy as to the relation between these two - the manual says for rthal_trap_catch() '...uncontrolled exception or fault is caught at machine level.'; does this include scheduling overruns? it seems not to I guess
> 
> I have both in place but unsure atm what rthal_trap_catch() would buy me ontop


There is not relation whatsoever between these three services.

-- 
                                                                Gilles.

Re: [Xenomai] kernel equivalent of SIGXCPU

[Gilles Chanteperdrix]

On 05/22/2013 01:26 PM, Gilles Chanteperdrix wrote:

> On 05/22/2013 12:01 PM, Michael Haberler wrote:
> 
>> I'm trying to trap scheduling violations through an exception handler
> 
> 
> How do you define "scheduling violations" ?
> 
>>
>> in user RT it's straightforward - use the SIGXCPU handler
> 
> 
> No, SIGXCPU detect involuntary mode switches to secondary mode, if you
> have the XNWARNSW bit set, it traps Linux system calls made by a thread
> running in secondary mode.
> 
>>
>> is rthal_trap_catch() the way to go? 
> 
> 
> rthal_trap_catch, allows to trap machine exceptions.
> 
>>
>> or is it just evaluating the rt_task_wait_period() returns ? 
> 
> 
> rt_task_wait_period returns an error when an overrun happens, that is
> when the timer ticks twice without the periodic thread having called
> rt_task_wait_period.


Sorry, when the thread finally wakes up more than one period after its
expected wake up time. So, when the timer ticks twice without the
periodic thread having been scheduled out of rt_taskw_wait_period.

-- 
                                                                Gilles.