/** Linux specific real-time optimizations
 *
 * @author Steffen Vogel <stvogel@eonerc.rwth-aachen.de>
 * @copyright 2017, Institute for Automation of Complex Power Systems, EONERC
 *********************************************************************************/

#include <sched.h>
#include <unistd.h>

#include "config.h"
#include "utils.h"
#include "cfg.h"

#include "kernel/kernel.h"
#include "kernel/rt.h"

int rt_init(int priority, int affinity)
{ INDENT
	int is_rt;

	/* Use FIFO scheduler with real time priority */
	is_rt = rt_is_preemptible();
	if (is_rt)
		warn("We recommend to use an PREEMPT_RT patched kernel!");

	if (priority)
		rt_set_priority(priority);
	else
		warn("You might want to use the 'priority' setting to increase VILLASnode's process priority");

	if (affinity)
		rt_set_affinity(affinity);
	else
		warn("You should use the 'affinity' setting to pin VILLASnode to dedicate CPU cores");

	return 0;
}

int rt_set_affinity(int affinity)
{
	char isolcpus[255];
	int is_isol, ret;

	/* Pin threads to CPUs by setting the affinity */
	cpu_set_t cset_pin, cset_isol, cset_non_isol;

	cpuset_from_integer(affinity, &cset_pin);

	is_isol = kernel_get_cmdline_param("isolcpus", isolcpus, sizeof(isolcpus));
	if (is_isol) {
		warn("You should reserve some cores for VILLASnode (see 'isolcpus')");

		CPU_ZERO(&cset_isol);
	}
	else {
		ret = cpulist_parse(isolcpus, &cset_isol, 0);
		if (ret)
			error("Invalid isolcpus cmdline parameter: %s", isolcpus);

		CPU_XOR(&cset_non_isol, &cset_isol, &cset_pin);
		if (CPU_COUNT(&cset_non_isol) > 0) {
			char isol[128], pin[128];
	
			cpulist_create(isol, sizeof(isol), &cset_isol);
			cpulist_create(pin, sizeof(pin), &cset_pin);

			warn("Affinity setting includes cores which are not isolated: affinity=%s isolcpus=%s", pin, isol);
		}
	}

	char list[128];
	cpulist_create(list, sizeof(list), &cset_pin);

	ret = sched_setaffinity(0, sizeof(cpu_set_t), &cset_pin);
	if (ret)
		serror("Failed to set CPU affinity to %s", list);

	debug(LOG_KERNEL | 3, "Set affinity to %s", list);
	
	return 0;
}

int rt_set_priority(int priority)
{
	int ret;
	struct sched_param param = {
		.sched_priority = priority
	};

	ret = sched_setscheduler(0, SCHED_FIFO, &param);
	if (ret)
		serror("Failed to set real time priority");

	debug(LOG_KERNEL | 3, "Task priority set to %u", priority);
	
	return 0;
}

int rt_is_preemptible()
{
	return access(SYSFS_PATH "/kernel/realtime", R_OK);
}