Author: mav
Date: Fri Aug 3 09:08:20 2012
New Revision: 239005
URL: http://svn.freebsd.org/changeset/base/239005
Log:
Microoptimize time math. As soon as our event periods are always below ome
second we may not add intereger parts by using bintime_addx() instead of
bintime_add(). Profiling shows handleevents() time redction by 15%.
Modified:
head/sys/kern/kern_clocksource.c
Modified: head/sys/kern/kern_clocksource.c
==============================================================================
--- head/sys/kern/kern_clocksource.c Fri Aug 3 05:39:32 2012
(r239004)
+++ head/sys/kern/kern_clocksource.c Fri Aug 3 09:08:20 2012
(r239005)
@@ -205,19 +205,21 @@ handleevents(struct bintime *now, int fa
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 fa
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
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