>Did some more testing and it gets even weirder. When I boot in always
>low I powernowd warns that the CPU speeds is 600. When I boot in aways
>high, it reports 1200. The CPU ranges from 800-1600. psrinfo reports
>these values when booted. How does powernowd determine the frequency?
It reads the CPU's registers:
static uint32_t
get_state_speedstep(int *freq)
{
uint64_t reg = rdmsr(IA32_MSR_PERF_STATUS);
uint32_t st = IA32_MSR_CUR_PSTATE(reg);
*freq = IA32_PSTATE_FREQ(st);
if (debug_est)
check_throttling();
return (st);
}
No idea whether this code is proper.
Casper
