HP-UX

I get my CPU speed use pstat APIs
use this program serach google and just test it
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/param.h>
#include <sys/pstat.h>
#define CPU_ID 0
#define HZ_PER_MHZ 1000000
int main()
{
struct pst_processor pst;
union pstun pu;

pu.pst_processor = &pst;
pstat( PSTAT_PROCESSOR, pu, (size_t)sizeof(pst), (size_t)1, CPU_ID);
printf( "%d MHz\n",(int)((double)pst.psp_iticksperclktick * sysconf( _SC_CLK_TCK ) / HZ_PER_MHZ) );

return 0;
}


the resutl shows 399MZ
but I use machinfo command shows 1.59Gz

what's wrong with that code or my machine

my OS is HP UX 11.31 Itanium base