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For the amd64 platform, we can depend on the TSC being present. This patch

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changes DELAY to use the TSC once it has been calibrated.  This does NOT
use the TSC for long-term timekeeping.   It only uses it to bound the
DELAY() spinloop.  This should not be affected by the Athlon64 X2 TSC
quirks because the cpu is not halted while we use DELAY().
This commit is contained in:
Peter Wemm 2005-12-12 22:27:07 +00:00
parent fbd68c4b4c
commit 6bcdd71391
1 changed files with 15 additions and 0 deletions
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15
sys/amd64/isa/clock.c
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@ -61,6 +61,7 @@ __FBSDID("$FreeBSD$");
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/module.h>
#include <sys/sched.h>
#include <sys/sysctl.h>
#include <sys/cons.h>
#include <sys/power.h>
@ -269,7 +270,21 @@ DELAY(int n)
int getit_calls = 1;
int n1;
static int state = 0;
#endif
if (tsc_freq != 0 && !tsc_is_broken) {
uint64_t start, end, now;
sched_pin();
start = rdtsc();
end = start + (tsc_freq * n) / 1000000;
do {
now = rdtsc();
} while (now < end || (now > start && end < start));
sched_unpin();
return;
}
#ifdef DELAYDEBUG
if (state == 0) {
state = 1;
for (n1 = 1; n1 <= 10000000; n1 *= 10)