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user a read barrier instead of a normal barrier to serialize calls of rdtsc

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This commit is contained in:
Stefan Lankes 2012-07-19 08:28:23 +02:00
parent 6462e2b0fd
commit ae1216f757
3 changed files with 8 additions and 7 deletions
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4
arch/x86/kernel/apic.c
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@ -589,10 +589,10 @@ int apic_calibration(void)
lapic_write(APIC_ICR, 0xFFFFFFFFUL);
/* wait 3 time slices to determine a ICR */
mb();
rmb();
start = rdtsc();
do {
mb();
rmb();
end = rdtsc();
ticks = end > start ? end - start : start - end;
} while(ticks*TIMER_FREQ < 3*RC_REFCLOCKMHZ*1000000UL);

4
arch/x86/kernel/processor.c
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@ -149,12 +149,12 @@ uint32_t detect_cpu_frequency(void)
while((ticks = get_clock_tick()) - old == 0)
HALT;
mb();
rmb();
start = rdtsc();
/* wait a second to determine the frequency */
while(get_clock_tick() - ticks < TIMER_FREQ)
HALT;
mb();
rmb();
end = rdtsc();
diff = end > start ? end - start : start - end;

7
arch/x86/kernel/timer.c
View file

@ -50,8 +50,8 @@ uint64_t get_clock_tick(void)
void start_tickless(void)
{
use_tickless = 1;
rmb();
last_rdtsc = rdtsc();
mb();
}
void end_tickless(void)
@ -71,11 +71,11 @@ void check_ticks(void)
{
uint64_t curr_rdtsc = rdtsc();
mb();
rmb();
if (curr_rdtsc - last_rdtsc > 1000000ULL*(uint64_t)get_cpu_frequency() / (uint64_t)TIMER_FREQ) {
timer_ticks++;
last_rdtsc = curr_rdtsc;
mb();
rmb();
}
}
}
@ -115,6 +115,7 @@ static void timer_handler(struct state *s)
vga_puts("One second has passed\n");
}*/
kputs("A");
/* Dump load every minute */
//if (timer_ticks % (TIMER_FREQ*60) == 0)
// dump_load();