Hi folks...
recently I did a simple experiment, that was running a CPU bound program
on Linux kernels with different HZ setting. I pick three, HZ=100,
HZ=250 and HZ=250. Here is the result:
HZ=100 HZ=250 HZ=1000
Real 319.326 317.786 319.072
User 319.33 317.801 319.094
System 0 0.001 0
The result was taken by simply running the program with "time" command.
The programs were ran 4 time each and the average was calculate for all
real, user and system time.
If you look closely, perhaps you will be shocked with the number. On
HZ=250, the program seems running faster than the other two. I almost
can believe it, as I suspected that it should run slower due to more
work on taking care the interrupts. Anybody can kindly explain what
happened here?
Here is the program I used for the test:
#include<stdio.h>
#include<stdlib.h>
int main(int argc, char *argv[])
{
int i, j;
long int l, m;
unsigned long int k,loop_max;
float hasil;
if (argc >= 2) {
loop_max = labs(strtoul(argv[1], (char **) NULL, 10));
} else
loop_max = 1000;
printf("loop_max is %lu\n", loop_max);
for (i = 0; i <= 3000; i++)
for (j = 0; j <= 1000; j++)
for (k = 0; k <= loop_max; k++) {
l = random();
do {
m = random();
} while (m == 0);
hasil = l / m;
}
return (0);
}
regards,
Mulyadi
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