Not sure which one would be right section to put this thread on.
I installed Suse 11.1 and slightly modified the original kernel to obtain required CPU clock ticks
Un-check the Tickless option
Timer Frequency - 1000Hz
Below is the piece of code, which actually shows Frequency and clock ticks. it suppose to print a statement to konsole every 1000Hz
#include <signal.h>
#include <sys/time.h>
#include <iostream>
#include <cstdlib>
using namespace std;
long long int counter = 0;
struct timeval last_time;
struct timeval curr_time;
double dif = 0.0;
double freq_sum = 0.0;
double reps = 0.0;
double freq_min = 99999.0;
double freq_max = 0.0;
long long int num_too_low = 0;
void time_check(int data)
{
// work out the frequecy of the SIGALRMs
++counter;
if (counter >= 1000)
{
// need to work out time since last 1000 ticks
gettimeofday(&curr_time, NULL);
dif = ((curr_time.tv_usec + curr_time.tv_sec * 1000000)
- (last_time.tv_usec + last_time.tv_sec * 1000000));
double freq = (counter / dif) * 1000000;
freq_sum = ((freq_sum * reps) + freq) / (reps + 1) ;
++reps;
// if (freq < 800)
cout << "Frequency = " << freq << " reps= " << dif / 1000000 << endl;
if (freq_min > freq) freq_min = freq;
if (freq_max < freq) freq_max = freq;
if (freq < 950)
++num_too_low;
last_time = curr_time;
counter = 0;
}
}
int main (int argc, char * argv])
{
cout << "go" /* << "\a \a \a" */ << endl;
int res;
gettimeofday(&last_time, NULL);
struct sigaction action;
struct itimerval timer_value;
timer_value.it_value.tv_sec = 0;
timer_value.it_value.tv_usec = 1;
timer_value.it_interval.tv_sec = 0;
timer_value.it_interval.tv_usec = 1;
action.sa_handler = time_check;
action.sa_flags = SA_NOMASK;
sigemptyset(&action.sa_mask);
sigaction( SIGALRM, &action, NULL);
res = setitimer( ITIMER_REAL, &timer_value, NULL );
if (res == -1)
cout << "error in setitimer" << endl;
cout << "Starting CPU Test program" << endl;
// loop for a long time
while (reps < 3000.0)
{
sleep(1);
}
cout << "average CPU frequency = " << freq_sum << endl;
cout << "reps = " << reps << endl;
cout << "Min = " << freq_min << " Max = " << freq_max << endl;
cout << "number of low = " << num_too_low << endl;
return 0;
}
My observations on Suse
SUSE Version AVG. Frequency AVG. REPS
Suse 9.3 - 999.xxx 990.xxx reps > 1 (on average)
Suse 10.2 - 999.xxx 998.xxx reps (1 - 1.001)
Suse 10.3 - 1000.xxx 912.xxx reps (1 - 1.090)
but on 11.1
Suse 11.1 0 - 324263.xxx reps (-2e-0.6 upto 0.005112)
I dont know where things are going wrong. It is too wierd output. This issue was initially observerd on 10.3 where this was happend on and off but lack the cpu clock time. but in case of 11.1 its gone right above the graphs.
On Suse 9.3 it was ok not very good but could be the hardware issue.
On Suse 10.2 everything was spot on
On Suse 10.3 a bit slow but not very accurate
On Suse 11.1 no way near the required values
anyone knows how to fix this in suse 11.1, thanks for help in-advance.
