Okay, I realized how I was confusing clock tick (for timekeeping) and interrupt
latency and why the result were not the ones I expected.
I still have one question, is there a macro to choose/impose the processor
frequency ?
-----Message d'origine-----
De : BRIARD Sebastien
Envoyé : mardi 27 mars 2018 14:33
À : 'Sebastian Huber'; users@rtems.org
Objet : RE: Interrupt latency in RTEMS (Zedboard)
I am using the expiration of a timer. And basically I am doing two things:
- I keep measuring time in my main loop
- when I am in the handler I take a new measure of the time.
It was a quick, not so rigorous test, with global variables.
Here is the code :
// Global variable for tests //
volatile bool signal_sent;
rtems_interval lat=0 ;
rtems_id main_task;
//handler //
rtems_timer_service_routine test_signal_from_isr(rtems_id timer, void *arg)
{
rtems_interval *rag = (rtems_interval*)arg ;
lat = rtems_clock_get_uptime_nanoseconds() - *rag ;
signal_sent = TRUE;
}
// main task //
rtems_task Init( rtems_task_argument argument) {
rtems_status_code status;
rtems_id timer;
rtems_interval now;
// index to repeat test //
int i = 0 ;
main_task = rtems_task_self();
printf("ticks per seconds : %02ld \n",rtems_clock_get_ticks_per_second()) ;
/*
* Timer used in multiple ways
*/
status = rtems_timer_create( 1, &timer );
assert( status == RTEMS_SUCCESSFUL );
while(i<10)
{
/*
* Test Signal from ISR
*/
signal_sent = FALSE;
status = rtems_timer_fire_after( timer, 20, test_signal_from_isr, (void*)
&now );
assert( status == RTEMS_SUCCESSFUL );
while (1) {
now = rtems_clock_get_uptime_nanoseconds() ;
if ( signal_sent )
break;
}
printf(" interrupt latency : %ld ns \n",lat) ;
puts( "Signal sent from ISR has been processed" );
i++;
}
puts( "*** END OF SIGNAL FROM TSR TEST ***" );
exit( 0 ); // generera un RTEMS fatal
}
/* configuration information */
#define CONFIGURE_APPLICATION_NEEDS_CONSOLE_DRIVER
#define CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER
#define CONFIGURE_MICROSECONDS_PER_TICK 1
#define CONFIGURE_RTEMS_INIT_TASKS_TABLE
#define CONFIGURE_MAXIMUM_TASKS 1
#define CONFIGURE_MAXIMUM_TIMERS 1
#define CONFIGURE_INIT
#include <rtems/confdefs.h>
-----Message d'origine-----
De : Sebastian Huber [mailto:sebastian.hu...@embedded-brains.de]
Envoyé : mardi 27 mars 2018 14:20
À : BRIARD Sebastien; users@rtems.org
Objet : Re: Interrupt latency in RTEMS (Zedboard)
Hello Sebastien,
could you give a code example how you measure the interrupt latency?
Which interrupt do you use?
The time keeping is independent of the clock tick configuration.
--
Sebastian Huber, embedded brains GmbH
Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone : +49 89 189 47 41-16
Fax : +49 89 189 47 41-09
E-Mail : sebastian.hu...@embedded-brains.de
PGP : Public key available on request.
Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
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