TIMER_FREQ
tsc_diff, tsc_diff - hangcheck_tick*TIMER_FREQ);
hangcheck_tsc_margin *= TIMER_FREQ;
#define msec_to_cycles(msec) (TIMER_FREQ * (unsigned long)(msec) / 1000)
#define usec_to_cycles(usec) (TIMER_FREQ * (unsigned long)(usec) / 1000000)
#define cycles_to_usec(cycles) ((unsigned long)(cycles) * 1000000 / TIMER_FREQ)