/*
* Start the real-time and statistics clocks. Leave stathz 0 since there
* are no other timers available.
*/
void
cpu_initclocks()
{
if (clockdev == NULL)
panic("cpu_initclocks: no clock attached");
tick = 1000000 / hz; /* number of microseconds between interrupts */
tickfix = 1000000 - (hz * tick);
if (tickfix) {
int ftp;
ftp = min(ffs(tickfix), ffs(hz));
tickfix >>= (ftp - 1);
tickfixinterval = hz >> (ftp - 1);
}
/*
* Establish the clock interrupt; it's a special case.
*
* We establish the clock interrupt this late because if
* we do it at clock attach time, we may have never been at
* spl0() since taking over the system. Some versions of
* PALcode save a clock interrupt, which would get delivered
* when we spl0() in autoconf.c. If established the clock
* interrupt handler earlier, that interrupt would go to
* hardclock, which would then fall over because p->p_stats
* isn't set at that time.
*/
last_time = alpha_rpcc();
scaled_ticks_per_cycle = ((u_int64_t)hz << FIX_SHIFT) / cycles_per_sec;
max_cycles_per_tick = 2*cycles_per_sec / hz;
alpha_timecounter.tc_frequency = cycles_per_sec;
init_timecounter(&alpha_timecounter);
platform.clockintr = (void (*) __P((void *))) handleclock;
/*
* Get the clock started.
*/
CLOCK_INIT(clockdev);
}
int main() {
// show the monotonic time
// the latency for doing nothing
// with take 200 ~ 300 ns
CLOCK_INIT(mono);
CLOCK_MONO_BEGIN(mono);
CLOCK_MONO_END(mono);
CLOCK_PRINT(mono);
Clock::StructRdtsc s, e;
uint64_t d;
for (int i = 0; i < 1000; i++) {
Clock::rdtsc(s);
sleep(1);
Clock::rdtsc(e);
// see how many cycles rdtsc needs
d = e.cycles - s.cycles;
std::cout << d << std::endl;
}
}
