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// $Id$
#include "cpuload.h"
#include <stdio.h>
#include <sys/time.h>
#include <signal.h>
namespace
{
int calibration_time = 1000; //msec
unsigned long loop_count=0;
int calibration_done = 0;
volatile int done = 0;
unsigned long per_iter_loop_count;
unsigned long calibrated_loop_count;
}
static void
handle_signal (int signum)
{
switch (signum)
{
case SIGVTALRM:
//printf ("VTALRM recvd\n");
per_iter_loop_count = loop_count;
done = 1;
break;
default:
printf ("signal %d unexpected\n", signum);
}
}
int is_prime (const unsigned long n,
const unsigned long min_factor,
const unsigned long max_factor)
{
if (n > 3)
for (unsigned long factor = min_factor;
factor <= max_factor;
++factor)
if (n / factor * factor == n)
return factor;
return 0;
}
void do_computation (unsigned long& loop_count)
{
static unsigned long prime_number = 961989999;
++loop_count;
is_prime (prime_number, 2, prime_number/2);
}
unsigned long do_calibrate ()
{
per_iter_loop_count = 0;
loop_count = 0;
signal (SIGVTALRM, handle_signal);
itimerval timerval;
timerval.it_value.tv_sec = 0;
timerval.it_value.tv_usec = calibration_time*1000;
if (setitimer(ITIMER_VIRTUAL, &timerval, 0) != 0)
{
printf("setitimer failed\n");
}
for (;!done;)
{
do_computation (loop_count);
}
//printf("iter done\n");
done = 0;
return per_iter_loop_count;
}
void CPULoad::run (struct timeval& tv)
{
unsigned long loops=0;
unsigned long iters = (unsigned long)
(((float)calibrated_loop_count/(float)(calibration_time*1000)) *
(tv.tv_usec + tv.tv_sec*1000000));
iters = iters + 1;
// printf("tv = %lu sec %lu usec, iters = %lu\n",
// tv.tv_sec, tv.tv_usec, iters);
for (;iters>0;--iters)
{
//loops is really not used here. It is used only during calibration
do_computation (loops);
}
}
void CPULoad::calibrate (int num_iters)
{
if (calibration_done)
return;
printf("calibrating ...\n");
for (int i=0; i<num_iters; ++i)
{
unsigned long tmp = do_calibrate ();
//printf("calibration ended calibrated (%dmsec) loop_count = %lu\n",
// calibration_time, tmp);
if (calibrated_loop_count == 0)
{
calibrated_loop_count = tmp;
}
else
{
//calibrated_loop_count = (calibrated_loop_count + tmp)/2;
if (calibrated_loop_count < tmp)
calibrated_loop_count = tmp;
}
loop_count = 0;
}
calibration_done = 1;
signal (SIGVTALRM, SIG_DFL);
//printf("calibration done\n");
}
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