Date: Wed, 6 Jun 2012 15:29:27 +0000 (UTC) From: Davide Italiano <davide@FreeBSD.org> To: src-committers@freebsd.org, svn-src-projects@freebsd.org Subject: svn commit: r236682 - projects/calloutng/sys/kern Message-ID: <201206061529.q56FTRRF022440@svn.freebsd.org>
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Author: davide Date: Wed Jun 6 15:29:27 2012 New Revision: 236682 URL: http://svn.freebsd.org/changeset/base/236682 Log: There's no need to add one second to the event time in callout_cc_add() if this one is scheduled in the past. This was a braino derived from my previous experiments. Moreover, there's no need to call binuptime(), but, in turn, event times in the past may be silently converted to cc_softticks, avoiding the bintime() overhead. As an added bonus, we can avoid to start our scan of the wheel 1/HZ backward in the past, gaining in terms of performances. Reported by: mav Modified: projects/calloutng/sys/kern/kern_timeout.c Modified: projects/calloutng/sys/kern/kern_timeout.c ============================================================================== --- projects/calloutng/sys/kern/kern_timeout.c Wed Jun 6 14:31:14 2012 (r236681) +++ projects/calloutng/sys/kern/kern_timeout.c Wed Jun 6 15:29:27 2012 (r236682) @@ -363,7 +363,6 @@ callout_tick(void) struct callout_cpu *cc; struct callout_tailq *sc; struct bintime now; - struct bintime bt; struct bintime limit; struct bintime next; int cpu, first, flag, future, last, need_softclock; @@ -376,13 +375,6 @@ callout_tick(void) cc = CC_SELF(); mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET); binuptime(&now); - /* - * getbinuptime() may be inaccurate and return time up to 1/HZ in the past. - * In order to avoid the possible loss of one or more events look back 1/HZ - * in the past from the time we last checked. - */ - FREQ2BT(hz,&bt); - bintime_sub(&cc->cc_softticks,&bt); first = callout_hash(&cc->cc_softticks); last = callout_hash(&now); /* @@ -477,16 +469,10 @@ callout_cc_add(struct callout *c, struct struct bintime to_bintime, void (*func)(void *), void *arg, int cpu) { int bucket; - struct bintime now; - struct bintime tmp; - tmp.sec = 1; - tmp.frac = 0; CC_LOCK_ASSERT(cc); - binuptime(&now); - if (bintime_cmp(&to_bintime, &now, <)) { - bintime_add(&now, &tmp); - to_bintime = now; + if (bintime_cmp(&to_bintime, &cc->cc_softticks, <)) { + to_bintime = cc->cc_softticks; } c->c_arg = arg; c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING);
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