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#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <sched.h>
#include "litmus.h"
#include "internal.h"
static void tperrorx(char* msg)
{
fprintf(stderr,
"Task %d: %s: %m",
gettid(), msg);
exit(-1);
}
/* common launch routine */
int __launch_rt_task(rt_fn_t rt_prog, void *rt_arg, rt_setup_fn_t setup,
void* setup_arg)
{
int ret;
int rt_task = fork();
if (rt_task == 0) {
/* we are the real-time task
* launch task and die when it is done
*/
rt_task = gettid();
ret = setup(rt_task, setup_arg);
if (ret < 0)
tperrorx("could not setup task parameters");
ret = task_mode(LITMUS_RT_TASK);
if (ret < 0)
tperrorx("could not become real-time task");
exit(rt_prog(rt_arg));
}
return rt_task;
}
int __create_rt_task(rt_fn_t rt_prog, void *arg, int cpu, int wcet, int period,
task_class_t rt_class)
{
struct rt_task params;
params.cpu = cpu;
params.period = period;
params.exec_cost = wcet;
params.cls = rt_class;
params.phase = 0;
/* enforce budget for tasks that might not use sleep_next_period() */
params.budget_policy = QUANTUM_ENFORCEMENT;
return __launch_rt_task(rt_prog, arg,
(rt_setup_fn_t) set_rt_task_param, ¶ms);
}
int create_rt_task(rt_fn_t rt_prog, void *arg, int cpu, int wcet, int period) {
return __create_rt_task(rt_prog, arg, cpu, wcet, period, RT_CLASS_HARD);
}
#define SCHED_NORMAL 0
#define SCHED_LITMUS 6
int task_mode(int mode)
{
struct sched_param param;
int me = gettid();
int policy = sched_getscheduler(gettid());
int old_mode = policy == SCHED_LITMUS ? LITMUS_RT_TASK : BACKGROUND_TASK;
param.sched_priority = 0;
if (old_mode == LITMUS_RT_TASK && mode == BACKGROUND_TASK) {
/* transition to normal task */
return sched_setscheduler(me, SCHED_NORMAL, ¶m);
} else if (old_mode == BACKGROUND_TASK && mode == LITMUS_RT_TASK) {
/* transition to RT task */
return sched_setscheduler(me, SCHED_LITMUS, ¶m);
} else {
errno = -EINVAL;
return -1;
}
}
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