minimiser l'utilisation du CPU

bon même avec sched_yield ça ne marche pas !!! :( je poste tout mon code si une personne peut m'aider ... le plus important et dans la fonction int main(void)

#include <stdlib.h>
#include <curses.h>
#include <time.h>
#include <pthread.h>
#include <unistd.h>
#include <linux/unistd.h> /* les macros _syscallX */
#include <linux/kernel.h> /* pour struct sysinfo */
#include <sys/utsname.h>
#include <sched.h>
#define ENTER		13
#define ESCAPE		27
#define PROC_MEM	"/proc/meminfo"
#define PROC_CPU	"/proc/"
#define PROC_HDD	"/proc/"
// question forum http://linuxfr.org/forums/19/18977.html
//setpriority(2), sched_yield(2)
WINDOW *menubar, *memwin, *cpuwin, *hddwin, *sup_info;
WINDOW *sub_mem, *sub_cpu, *sub_hdd;
time_t d_time;
struct sysinfo s_info;
struct utsname u_name;
typedef struct {
	int processor;
	char *vendor_id;
	int cpu_family;
	char *model_name;
	float cpu_mhz;
	int cache_size;
	int cpuid_level;
} CPU; 
void init_curses(void) {
	initscr();
	start_color();
	init_pair(1, COLOR_WHITE, COLOR_BLUE);
	init_pair(2, COLOR_BLUE, COLOR_WHITE);
	init_pair(3, COLOR_RED, COLOR_WHITE);
	init_pair(4, COLOR_RED, COLOR_YELLOW);
	init_pair(5, COLOR_GREEN, COLOR_BLUE);
	init_pair(6, COLOR_RED, COLOR_BLUE);
	curs_set(0);
	noecho();
	keypad(stdscr, TRUE);
}
void menu_bar(void) {
	menubar = subwin(stdscr, 1,63, 26,0);
	wbkgd(menubar, COLOR_PAIR(2));
	wattron(menubar, COLOR_PAIR(3));
	waddstr(menubar, "ESC");
	wattroff(menubar, COLOR_PAIR(3));
	waddstr(menubar, " : EXIT |");
	wattron(menubar, COLOR_PAIR(3));
	waddstr(menubar, u_name.sysname);
	wattroff(menubar, COLOR_PAIR(3));
	waddstr(menubar, "|");
	wattron(menubar, COLOR_PAIR(3));
	waddstr(menubar, u_name.machine);
	wattroff(menubar, COLOR_PAIR(3));
	waddstr(menubar, "|");
	wattron(menubar, COLOR_PAIR(3));
	waddstr(menubar, u_name.release);
	wattroff(menubar, COLOR_PAIR(3));
	waddstr(menubar, "| ");
	wprintw(menubar, "%s", ctime(&d_time));
}
void set_title(void) {
	wmove(memwin, 0, 2);
	wattron(memwin, COLOR_PAIR(5));
	waddstr(memwin, "Utilisation de la RAM");
	wattroff(memwin, COLOR_PAIR(5));
	wmove(cpuwin, 0, 2);
	wattron(cpuwin, COLOR_PAIR(5));
	waddstr(cpuwin, "Info CPU");
	wattroff(cpuwin, COLOR_PAIR(5));
	wmove(hddwin, 0, 2);
	wattron(hddwin, COLOR_PAIR(5));
	waddstr(hddwin, "Info Hard Disk Drive");
	wattroff(hddwin, COLOR_PAIR(5));
}
void create_sub_win(void) {
	sub_mem = subwin(memwin, 23, 29, 1, 1);
//	sub_cpu = subwin(cpuwin, 5, 15, 1, 20);
//	box(sub_cpu, ACS_VLINE, ACS_HLINE);
//	sub_hdd = subwin(hddwin, 5, 15, 1, 15);
//	box(sub_hdd, ACS_VLINE, ACS_HLINE);
}
void info_sup(void) {
	sysinfo(&s_info);
	werase(sup_info);
	box(sup_info, ACS_VLINE, ACS_HLINE);
	wmove(sup_info, 1, 1);
	wprintw(sup_info, "- uptime : ");
	wattron(sup_info, COLOR_PAIR(6));
	wprintw(sup_info, "%d", s_info.uptime);
	wattroff(sup_info, COLOR_PAIR(6));
	wprintw(sup_info, " sec");
	wmove(sup_info, 3, 1);
	wprintw(sup_info, "- processus active : ");
	wattron(sup_info, COLOR_PAIR(6));
	wprintw(sup_info, "%d", s_info.procs);
	wattroff(sup_info, COLOR_PAIR(6));
	wrefresh(sup_info);
}
int main(void) {
	int key, i=0;
	FILE *meminfo;
	char value[256];
	struct tm up_time;
	time(&d_time);
	uname(&u_name);
	init_curses();		// initialisation de curses
	bkgd(COLOR_PAIR(1));
	memwin = subwin(stdscr,26,33,0,0);
	box(memwin, ACS_VLINE, ACS_HLINE);
	cpuwin = subwin(stdscr, 10, 30, 0, 33);
	box(cpuwin, ACS_VLINE, ACS_HLINE);
	hddwin = subwin(stdscr, 11, 30, 10, 33);
	box(hddwin, ACS_VLINE, ACS_HLINE);
	sup_info = subwin(stdscr, 5, 30, 21, 33);
	box(sup_info, ACS_VLINE, ACS_HLINE);
	menu_bar();
	set_title();
	create_sub_win();
	refresh();
	// CODE A PLACER DANS UN THREAD
	while(1) {
		werase(sub_mem);
 	 if((meminfo = fopen(PROC_MEM, "r")) != NULL) {
 		 while(fgets(value, sizeof(value), meminfo)) {
 			 if(value[0] != '#') {
					i+=1;
					wmove(sub_mem, i, 1);
 	 wprintw(sub_mem, "- %s", value);
				}
			}
			i=0;
 	fclose(meminfo);
		}
		info_sup();
		wrefresh(sub_mem);
		sched_yield();
	}
	// FIN DU CODE
	getch();
	delwin(cpuwin);
	delwin(memwin);
	delwin(menubar);
	endwin();
	return 0;
}