rt_process.c

fsmlabs的real time linux的内核

/*
 * RTLinux scheduling accuracy measuring example
 *
 * (C) Michael Barabanov, 1997
 *  (C) FSMLabs  1999. [e-mail]
 *  Released under the GNU GENERAL PUBLIC LICENSE Version 2, June 1991
 *  Any use of this code must include this notice.
 */

#include <rtl.h>
#include <rtl_fifo.h>
#include <time.h>
#include <rtl_sched.h>
#include <rtl_sync.h>
#include <pthread.h>
#include <unistd.h>
#include <rtl_debug.h>
#include <errno.h>
#include "common.h"

int ntests=500;
int period=1000000;
int bperiod=3100000;
int mode=0;
int absolute=0;
int fifo_size=4000;
int advance=0;

MODULE_PARM(period,"i");
MODULE_PARM(bperiod,"i");
MODULE_PARM(ntests,"i");
MODULE_PARM(mode,"i");
MODULE_PARM(absolute,"i");
MODULE_PARM(advance,"i");

MODULE_AUTHOR("Michael Barabanov FSMLabs Inc.");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("scheduling jitter measurement");

pthread_t thread;
int fd_fifo;


void *thread_code(void *param)
{
	hrtime_t expected;
	hrtime_t diff;
	hrtime_t now;
	hrtime_t last_time = 0;
	hrtime_t min_diff;
	hrtime_t max_diff;
	struct sample samp;
	int i;
	int cnt = 0;
	int cpu_id = rtl_getcpuid();

	rtl_printf ("Measurement task starts on CPU %d\n", cpu_id);
	if (mode) {
		int ret = rtl_setclockmode (CLOCK_REALTIME, RTL_CLOCK_MODE_PERIODIC, period);

		if (ret != 0) {
			conpr("Setting periodic mode failed\n");
			mode = 0;
		}
	} else {

		rtl_setclockmode (CLOCK_REALTIME, RTL_CLOCK_MODE_ONESHOT, 0);
	}

	expected = clock_gethrtime(CLOCK_REALTIME) + 2 * (hrtime_t) period;


	fd_fifo = open("/dev/rtf0", O_NONBLOCK);
	if (fd_fifo < 0) {
		rtl_printf("/dev/rtf0 open returned %d\n", fd_fifo);
		return (void *) -1;
	}

	if (advance) {
		rtl_stop_interrupts(); /* Be careful with this! The task won't be preempted by anything else. This is probably only appropriate for small high-priority tasks. */
	}

	/* first cycle */
	clock_nanosleep (CLOCK_REALTIME, TIMER_ABSTIME, hrt2ts(expected - advance), NULL);
	expected += period;
	now = clock_gethrtime(CLOCK_MONOTONIC);
	last_time = now;

	do {
		min_diff = 2000000000;
		max_diff = -2000000000;

		for (i = 0; i < ntests; i++) {
			++cnt;
			clock_nanosleep (CLOCK_REALTIME, TIMER_ABSTIME, hrt2ts(expected - advance), NULL);

			now = clock_gethrtime(CLOCK_MONOTONIC);
			if (absolute && advance && !mode) {
				if (now < expected) {
					rtl_delay (expected - now);
				}
				now = clock_gethrtime(CLOCK_MONOTONIC);
			}
			if (absolute) {
				diff = now - expected;
			} else {
				diff = now - last_time - period;
				if (diff < 0) {
					diff = -diff;
				}
			}
			if (diff < min_diff) {
				min_diff = diff;
			}
			if (diff > max_diff) {
				max_diff = diff;
			}

			expected += period;
			last_time = now;
		}

		samp.min = min_diff;
		samp.max = max_diff;
		write (fd_fifo, &samp, sizeof(samp));
	} while (1);
	return 0;
}

pthread_t background_threadid;

void *background_thread(void *param)
{
	hrtime_t next = clock_gethrtime(CLOCK_REALTIME);
	while (1) {
		hrtime_t t = gethrtime ();
		next += bperiod;
		/* the measurement task should preempt the following loop */
		while (gethrtime() < t + bperiod * 2 / 3);
		clock_nanosleep (CLOCK_REALTIME, TIMER_ABSTIME, hrt2ts(next), NULL);
	}
}


int init_module(void)
{
	pthread_attr_t attr;
	struct sched_param sched_param;
	int thread_status;
        int fifo_status;

	rtf_destroy(0);
	fifo_status = rtf_create(0, fifo_size);
	if (fifo_status) {
		rtl_printf("RTLinux measurement test fail. fifo_status=%d\n",fifo_status);
		return -1;
	}


	rtl_printf("RTLinux measurement module on CPU %d\n",rtl_getcpuid());
	pthread_attr_init (&attr);
	if (rtl_cpu_exists(1)) {
		pthread_attr_setcpu_np(&attr, 1);
	}
	sched_param.sched_priority = 1;
	pthread_attr_setschedparam (&attr, &sched_param);
	rtl_printf("About to thread create\n");
	thread_status = pthread_create (&thread,  &attr, thread_code, (void *)1);
	if (thread_status != 0) {
		rtl_printf("failed to create RT-thread: %d\n", thread_status);
		return -1;
	} else {
		rtl_printf("created RT-thread\n");
	}

	if (bperiod) {
		pthread_create (&background_threadid,  NULL, background_thread, NULL);
	}
	return 0;
}


void cleanup_module(void)
{
        rtl_printf ("Removing module on CPU %d\n", rtl_getcpuid());
	pthread_cancel (thread);
	pthread_join (thread, NULL);
	close(fd_fifo);
	rtf_destroy(0);
	if (bperiod) {
		pthread_cancel (background_threadid);
		pthread_join (background_threadid, NULL);
	}
}