Re: [Xenomai-help] Problems with rt_task_create and rt_task_join

[Michel Rinaldi <automation.03@domain.hid>]

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----- Messaggio originale ----- 
Da: "Gilles Chanteperdrix" <gilles.chanteperdrix@xenomai.org> 
A: "Michel Rinaldi" <automation.03@domain.hid> 
Cc: xenomai@xenomai.org
Inviato: Lunedì, 24 gennaio 2011 15:27:51 GMT +01:00 Amsterdam/Berlino/Berna/Roma/Stoccolma/Vienna 
Oggetto: Re: [Xenomai-help] Problems with rt_task_create and rt_task_join 

..... 

>You explanations are hard to follow and understand, and what is more, 
>ambiguous. Send us a piece of code which allows us to reproduce this 
>issue. Trying to make it as simple as possible. For instance seeing if 
>registering the interrupt causes any difference (if it does not make any 
>difference, then remove it, you get the idea). 

My code is really big and complex to reduce, I'll try to simplify it in next days. 

>As usual, we do not know what version of Xenomai, Adeos, Linux, etc... 
>you are using. See: 
>http://www.xenomai.org/index.php/Request_for_information 

I post them into firts mail of this thread, anyway they are: 
- Linux system with kernel 2.6.35.7 
- Xenomai 2.5.5.2 
- Adeos ipipe patch 2.7-04 
GCC is on version 4.4.3. 

..... 

>That is bad. One more question: what happens when you run the "latency" 
>test, do you get strange results? Also, I see that you have the SMI 
>workaround enabled, does it detect your chipset? 

Yes, as system log says, Xenomai detect SMI motherboard and disable them. 
I run the latency test: without other loads onto system, I observe values like these: 

RTT| 00:00:01 (periodic user-mode task, 100 us period, priority 99) 
RTH|----lat min|----lat avg|----lat max|-overrun|---msw|---lat best|--lat worst 
RTD| 6.680| 7.157| 12.187| 0| 0| 6.680| 12.187 
RTD| 6.277| 6.980| 10.519| 0| 0| 6.277| 12.187 
RTD| 1.175| 7.122| 9.315| 0| 0| 1.175| 12.187 
RTD| 1.578| 7.112| 9.382| 0| 0| 1.175| 12.187 
RTD| 1.635| 7.133| 10.307| 0| 0| 1.175| 12.187 

also after long runnings. 

But if I launch application contained into attached main_app.c file (that represents my simplified application) 
what I observe into latency test is: 

RTD| 1.635| 7.133| 10.307| 0| 0| 1.175| 12.187 
RTD| 1.591| 20.101| 129847.817| 1298| 0| 1.175| 129847.817 
RTD| 1.860| 7.133| 12.814| 1298| 0| 1.175| 129847.817 

Then, if I CTRL+C my app: 

RTD| 2.091| 7.468| 15.687| 1298| 0| 1.175| 129847.817 
RTD| 1.861| 8.397| 8157.893| 1379| 0| 1.175| 129847.817 
RTD| 6.282| 7.287| 15.007| 1379| 0| 1.175| 129847.817 

In concomitance with first very high latency, I observe into dmesg the clocksource switch message. 


In one case I observed an extremely bigger value for lat max: in facts, system freezed for about 2 seconds. 

RTD| 2.091| 7.468| 11.687| 0| 0| 1.133| 20.817 
RTD| 1.436| 254.870|-1819173.554| 24758| 0| 1.133|-1819173.554 
RTD| 1.768| 7.287| 12.007| 24758| 0| 1.133|-1819173.554 

I also observed that during same latency test the first application start generates the longest time in comparison to other starts. 

To run, my app needs kernel module contained into attached timer_module.c file, that signals a semaphore used by app every 1 ms. 
I don't observe some strange variations in latency test values when inserting or removing this kernel module. 

Thank you very much for your help, Gilles. 
Regards 
Mauro 


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[-- Attachment #2: main_app.c --]
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#include <native/task.h>
#include <native/timer.h>
#include <native/sem.h>
#include <native/heap.h>
#include <rtdk.h>

#include <signal.h>
#include <unistd.h>
#include <sys/io.h>
#include <sys/mman.h>
#include <bits/local_lim.h>

#define REQMGR_SHM_NAME             "R_ST_M"
#define REQMGR_STRUCT_SEM_NAME      "R_ST_S"

static unsigned char bBreakReqLoop = 0;
static unsigned char bBreakLoop = 0;

static RT_TASK tMainTask;
static RT_TASK tSchedTask;

static RT_SEM lpTimerSem;
static RT_HEAP main_heap;

typedef struct _tag_ReqStruct
{

   RT_SEM lpStartSem;

   /* .... */

}  ReqStruct;
ReqStruct* lpRequest;

static void SignalHandler ( int signal )
{
   rt_printf("sighandler called\n");
   bBreakReqLoop = 1;
}


void SchedThreadProc ( void *unused )
{
	rt_printf ( "Scheduler thread ready for execution\n" );

      while ( !bBreakLoop )
      {

         rt_sem_p ( &lpTimerSem, TM_INFINITE );

         /* do some work */

      }


   return;
}


int main ( void )
{
	int nRet = 0;

	mlockall ( MCL_CURRENT | MCL_FUTURE );
	
	rt_print_auto_init(1);

	if (rt_task_shadow(&tMainTask,"RTKER",0,0) == 0)
	{
		nRet = rt_sem_bind( &lpTimerSem, "SEMTIM", TM_NONBLOCK);
		if ( nRet == 0 )
		{  

			if (rt_heap_create(&main_heap,REQMGR_SHM_NAME,sizeof(ReqStruct),H_SHARED) == 0)
			{

				nRet = rt_heap_alloc(&main_heap,sizeof(ReqStruct),TM_NONBLOCK,(void **)&lpRequest);
				if ( nRet == 0)
				{

					if (rt_sem_create ( &lpRequest->lpStartSem, REQMGR_STRUCT_SEM_NAME, 0, S_FIFO ) == 0 )
					{

						rt_task_create(&tSchedTask, "SKER_T", 0, 99, T_JOINABLE);

						signal( SIGTERM , SignalHandler );
						signal( SIGINT, SignalHandler );

						rt_task_start(&tSchedTask, SchedThreadProc, NULL);

						rt_printf ( "Request management thread ready for execution\n" );

						while ( !bBreakReqLoop )
						{
							// check semaphore signalling (signalled
							nRet = rt_sem_p_until ( &lpRequest->lpStartSem , 1000000000 );
							if ( nRet == 0 )
							{

								/* work loop */

							}

							rt_task_sleep ( 10000000 );
						} /* end while */

						//Request scheduling thread to exit
						bBreakLoop = 1;

						rt_task_join(&tSchedTask);


						rt_sem_delete ( &lpRequest->lpStartSem );

						rt_heap_delete(&main_heap);

					}
					else
					{
						rt_printf("Semaphore creation error\n");
					}
					rt_heap_free(&main_heap,(void *)&lpRequest);
				}
				else
				{
					rt_printf("Heap alloc error %d\n",nRet);
				}
			}
			else
			{ 
				rt_printf("error creating heap\n");
			}
			rt_sem_unbind(&lpTimerSem);
		}
		else
		{
			rt_printf ("unable to find timer semaphore %d\n",nRet );
		}
	}
	else
	{
		rt_printf("error converting to Xenomai Task\n");
	}

	munlockall ( );
	rt_printf ( "END\n\n" );
	
	return 0;
}

[-- Attachment #3: timer_module.c --]
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#include <linux/kernel.h>
#include <linux/module.h>

#include <native/sem.h>
#include <rtdm/rtdm_driver.h>


#define SEM_NAME  "SEMTIM"

#define TIMER_PERIOD_NSEC	1000000

#define PERIODIC_TASK_PRIO	RTDM_TASK_HIGHEST_PRIORITY
#define PERIODIC_TASK_NAME	"T_PER"
#define PERIODIC_STACK_SIZE	8192

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Timer module");

static rtdm_task_t tPeriodicTask;

RT_SEM sSchedSem;

static void SwTimerHandler(void* dummy)
{
	
	printk(KERN_INFO "Starting %s\n", __FUNCTION__);
	
	while (1)
	{
	    if( rtdm_task_wait_period() == -ETIMEDOUT ) printk(KERN_WARNING "schedule overrun detected!\n");
		rt_sem_v(&sSchedSem);
	}
}


int init_module (void)
{
	int ErrCode;

	ErrCode = rt_sem_create(&sSchedSem, SEM_NAME, 0, S_FIFO);
	if ( ErrCode != 0)
	{
		printk(KERN_ERR "Error creating main semaphore %d!\n",ErrCode);
	}

	if (rtdm_task_init(&tPeriodicTask, PERIODIC_TASK_NAME, &SwTimerHandler, NULL, PERIODIC_TASK_PRIO, TIMER_PERIOD_NSEC) == 0)
	{
		printk(KERN_INFO "Periodic Thread created!");
	}

	return 0;
}

void cleanup_module (void)
{
	rtdm_task_destroy(&tPeriodicTask);

	rt_sem_delete(&sSchedSem);
	
	printk (KERN_INFO "Timer removed\n" );
}