Re: [Xenomai] First call to rt_timer_tsc() causes an unexpected switch to secondary mode.

[ZIV-Alberto Ozalla Cantabrana <alberto.ozalla@cgglobal.com>]

On 15/10/14 13:11, Gilles Chanteperdrix wrote:
> On 10/15/2014 12:59 PM, ZIV-Alberto Ozalla Cantabrana wrote:
>> Dear colleagues,
>>
>> I face an unexpected switch to secondary mode after the very first call to rt_timer_tsc() into a real-time task created by Xenomai.
>> This unexpected switch  only arises if it is the very first call to rt_timer_tsc().
> Hi,
>
> I see two possible reasons for that:
> - either on-demand mapping of library text page
> - or first access to the hardware register.
>
> In order to find which is the reason.
>
> Could you replace the call to rt_timer_tsc() with a call to __xn_rdtsc()
> after including asm/xenomai/tsc.h ?
>
>
Hello,

Thanks for the fast response.

Unfortunately replacing the call to rt_timer_tsc() with a call to 
__xn_rdtsc() does not solve the problem.

Another clue is that PF value increases at the same time as MSW.


CPU  PID    MSW        CSW        PF    STAT       %CPU  NAME
   0  0      0          11594571   0     00500080   96.3 ROOT/0
   0  1690   1          5339       1     00300184    1.0 Test_Task

It seems to be a first access to the hardware register.

Note: I use a call to mlockall(MCL_CURRENT|MCL_FUTURE) before creating 
the task.

-- 
Saludos,
Alberto Ozalla

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