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Avoid missing ticks and hardclock stopping.

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Submitted by:	tmm
This commit is contained in:
Jake Burkholder 2001-11-18 03:47:30 +00:00
parent a21a9d08d2
commit bf8f99b4b7
1 changed files with 27 additions and 1 deletions
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28
sys/sparc64/sparc64/tick.c
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@ -41,11 +41,37 @@ extern u_long tick_increment;
extern u_long tick_freq;
extern u_long tick_MHz;
int tick_missed; /* statistics */
#define TICK_GRACE 1000
void
tick_hardclock(struct clockframe *cf)
{
critical_t c;
int missed;
u_long next;
hardclock(cf);
wr(asr23, rd(asr23) + tick_increment, 0);
/*
* Avoid stopping of hardclock in case we missed one tick period by
* ensuring that the the value of the next tick is at least TICK_GRACE
* ticks in the future.
* Missed ticks need to be accounted for by repeatedly calling
* hardclock.
*/
missed = 0;
next = rd(asr23) + tick_increment;
c = critical_enter();
while (next < rd(tick) + TICK_GRACE) {
next += tick_increment;
missed++;
}
atomic_add_int(&tick_missed, missed);
wr(asr23, next, 0);
critical_exit(c);
for (; missed > 0; missed--)
hardclock(cf);
}
void