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/* getidle.c - by David van Moolenbroek <dcvmoole@cs.vu.nl> */
/* Usage:
*
* double idleperc;
* getidle();
* ...
* idleperc = getidle();
* if (idleperc >= 0.0)
* printf("CPU usage: %lg%%\n", 100.0 - idleperc);
*
* Notes:
* - This functionality can only be used by system processes.
* - Only one getidle() run is allowed per process at a time.
*
*/
#define _SYSTEM 1
#include <lib.h>
#include <minix/u64.h>
#include <minix/sysutil.h>
#include <minix/syslib.h>
#include <minix/minlib.h>
static u64_t start, idle;
static int running = 0;
static double make_double(u64_t d)
{
/* Convert a 64-bit fixed point value into a double.
* This whole thing should be replaced by something better eventually.
*/
double value;
size_t i;
value = (double) ex64hi(d);
for (i = 0; i < sizeof(unsigned long); i += 2)
value *= 65536.0;
value += (double) ex64lo(d);
return value;
}
double getidle(void)
{
u64_t stop, idle2;
u64_t idelta, tdelta;
double ifp, tfp, rfp;
int r;
if (!running) {
if ((r = sys_getidletsc(&idle)) != OK)
return -1.0;
running = 1;
read_tsc_64(&start);
return 0.0;
}
else {
read_tsc_64(&stop);
running = 0;
if ((r = sys_getidletsc(&idle2)) != OK)
return -1.0;
idelta = idle2 - idle;
tdelta = stop - start;
if (idelta >= tdelta)
return 100.0;
ifp = make_double(idelta);
tfp = make_double(tdelta);
rfp = ifp / tfp * 100.0;
if (rfp < 0.0) rfp = 0.0;
else if (rfp > 100.0) rfp = 100.0;
return rfp;
}
}
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