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Microoptimize time math. As soon as our event periods are always below ome

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second we may not add intereger parts by using bintime_addx() instead of
bintime_add().  Profiling shows handleevents() time redction by 15%.
This commit is contained in:
Alexander Motin 2012-08-03 09:08:20 +00:00
parent 369763e31a
commit c0722d20d3
1 changed files with 14 additions and 12 deletions
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26
sys/kern/kern_clocksource.c
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@ -205,19 +205,21 @@ handleevents(struct bintime *now, int fake)
runs = 0;
while (bintime_cmp(now, &state->nexthard, >=)) {
bintime_add(&state->nexthard, &hardperiod);
bintime_addx(&state->nexthard, hardperiod.frac);
runs++;
}
if ((timer->et_flags & ET_FLAGS_PERCPU) == 0 &&
bintime_cmp(&state->nexthard, &nexthard, >))
nexthard = state->nexthard;
if (runs && fake < 2) {
hardclock_cnt(runs, usermode);
done = 1;
if (runs) {
if ((timer->et_flags & ET_FLAGS_PERCPU) == 0 &&
bintime_cmp(&state->nexthard, &nexthard, >))
nexthard = state->nexthard;
if (fake < 2) {
hardclock_cnt(runs, usermode);
done = 1;
}
}
runs = 0;
while (bintime_cmp(now, &state->nextstat, >=)) {
bintime_add(&state->nextstat, &statperiod);
bintime_addx(&state->nextstat, statperiod.frac);
runs++;
}
if (runs && fake < 2) {
@ -227,7 +229,7 @@ handleevents(struct bintime *now, int fake)
if (profiling) {
runs = 0;
while (bintime_cmp(now, &state->nextprof, >=)) {
bintime_add(&state->nextprof, &profperiod);
bintime_addx(&state->nextprof, profperiod.frac);
runs++;
}
if (runs && !fake) {
@ -356,7 +358,7 @@ timercb(struct eventtimer *et, void *arg)
next = &nexttick;
if (periodic) {
now = *next; /* Ex-next tick time becomes present time. */
bintime_add(next, &timerperiod); /* Next tick in 1 period. */
bintime_addx(next, timerperiod.frac); /* Next tick in 1 period. */
} else {
binuptime(&now); /* Get present time from hardware. */
next->sec = -1; /* Next tick is not scheduled yet. */
@ -433,7 +435,7 @@ loadtimer(struct bintime *now, int start)
new.sec = 0;
new.frac = timerperiod.frac - tmp;
if (new.frac < tmp) /* Left less then passed. */
bintime_add(&new, &timerperiod);
bintime_addx(&new, timerperiod.frac);
CTR5(KTR_SPARE2, "load p at %d: now %d.%08x first in %d.%08x",
curcpu, now->sec, (unsigned int)(now->frac >> 32),
new.sec, (unsigned int)(new.frac >> 32));
@ -531,7 +533,7 @@ configtimer(int start)
if (start) {
/* Initialize time machine parameters. */
next = now;
bintime_add(&next, &timerperiod);
bintime_addx(&next, timerperiod.frac);
if (periodic)
nexttick = next;
else