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Date: Fri, 7 Feb 2014 15:07:04 +0000
From: Marcel van Mierlo <marcel.vanmierlo@marel.com>
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Subject: Re: [Xenomai] High CPU load using q_send under pSOS skin
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To: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
Cc: xenomai@xenomai.org


On 07/02/14 14:38, Gilles Chanteperdrix wrote:
> On 02/07/2014 03:32 PM, Marcel van Mierlo wrote:
>> If I comment out q_send TRAP 8 dosent occur. If I pass NULL as data
>> words to q_send, TRAP 8 stops... and %CPU remains low....hmmm do I need
>> to ensure stack alignment somehow?
>
> The stack alignment is ensured by the compiler. Starting with ARM 
> EABI, the stack is aligned on 8 bytes, so, if you do not use special 
> tricks (like casting a char * pointer to a u_long *pointer, or using 
> __attribute__((packed))), everything should be aligned properly. Could 
> you show us the declaration of the buffer passed to q_send ? In fact, 
> posting a self-contained, minimal example allowing to reproduce the 
> problem would help.
>

I will put together a self-contained minimal example (might be next 
week), but here is a complete working task function which exhibits high 
CPU. MSW still increases if I pass NULL but no messages are received....

Marcel.


TASK cio_watchdog_kick(void)
{
     u_long cantmsg[4];
     UL ulCanTQid;

     if (q_ident("cant", 0, (INT32 *)&ulCanTQid) != 0)
     {
         t_suspend(0);
     }

     while(1)
     {
         q_send(ulCanTQid, cantmsg);
         //q_send(ulCanTQid, NULL);
         tm_wkafter(100);
     }
}

LOCAL UL start_cio_watchdog_kick(void)
{
     UL ulRetval;
     UL ulTid;


     if ((ulRetval = t_create(   "CIOW",
                                 150,
                                 512,
                                 512,
                                 T_LOCAL,
                                 (INT32 *)&ulTid)) != 0)
     {
         return ulRetval;
     }

     if ((ulRetval = t_start( ulTid,
                             T_PREEMPT,
                             (void*)cio_watchdog_kick, 0)) != 0)
     {
         return ulRetval;
     }

     return 0;
}