kmalloc.c

fsmlabs的real time linux的内核

/* vim: set ts=4: */
/*
 * Copywrite 2002 Der Herr Hofrat
 * License GPL V2
 * Author [e-mail]
 */
/*
 * example of using kmalloc - basically you only need to call kmalloc but it
 * many cases it makes sense to not give up imediatly if the request is not
 * honored - so here we do it in a loop until we get something or time out.
 */
#include <rtl.h>
#include <time.h>
#include <pthread.h>
#include <linux/slab.h> /* kmalloc */

int size=128*1024 ; /* 128k - maximum posible */
void *mem_ptr; 
hrtime_t *rt_times;

pthread_t thread;

/* rt-thread that does nothing */
void * 
start_routine(void *arg)
{
	struct sched_param p;
	p . sched_priority = 1;
	rt_times = (hrtime_t *)mem_ptr; 
	pthread_setschedparam (pthread_self(), SCHED_FIFO, &p);
	pthread_make_periodic_np (pthread_self(), gethrtime(), 500000);

	while((void *)rt_times < (mem_ptr+size)){
		pthread_wait_np ();
		/* record the time we were woken up */
		*rt_times=gethrtime();
		rt_times++;
	}
	return (void *)0;
}

int 
init_module(void) 
{
	int attempts=0;

	/* don't give up imediatly if kmalloc fails */
	while ((mem_ptr = kmalloc(size, GFP_KERNEL)) == NULL && attempts < 5) {
		current->state   = TASK_INTERRUPTIBLE;
		schedule_timeout(HZ/10);
		attempts++;
	}

	memset(mem_ptr, 0, size);
	return pthread_create(&thread,NULL,start_routine, (void *)0);
}

void 
cleanup_module(void) 
{
	void * retval;
	int i;
	int len=(size/sizeof(hrtime_t));
	pthread_delete_np (thread);
	pthread_join(thread,&retval);
	printk("thread terminated with %d\n",(int)retval);

	/* run through the recorded data on rmmod */
	rt_times = (hrtime_t *)mem_ptr; 
	for(i=0;i<len;i++){
		printk("I was there at %Ld\n",*rt_times);
		rt_times++;
	}

	kfree(mem_ptr);
}