/* * RTLinux scheduling accuracy measuring example * * (C) Michael Barabanov, 1997 *  (C) FSMLabs  1999. baraban@fsmlabs.com *  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);	}}