Date: Fri, 8 Jun 2012 15:08:24 +0200 From: Davide Italiano <davide@freebsd.org> To: Attilio Rao <attilio@freebsd.org> Cc: svn-src-projects@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r236744 - in projects/calloutng/sys: kern sys Message-ID: <CACYV=-FD6qNAK_y532y3jQQhCh7Ct7venkEsxYmFBEiqZMPnyw@mail.gmail.com> In-Reply-To: <CAJ-FndB7QPRnmqrwyR9ixF9Jom8n7P1OMs=rczOKhmRxt08m3g@mail.gmail.com> References: <201206081153.q58BrqG2056771@svn.freebsd.org> <CAJ-FndB7QPRnmqrwyR9ixF9Jom8n7P1OMs=rczOKhmRxt08m3g@mail.gmail.com>
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On Fri, Jun 8, 2012 at 2:52 PM, Attilio Rao <attilio@freebsd.org> wrote: > 2012/6/8 Davide Italiano <davide@freebsd.org>: >> Author: davide >> Date: Fri Jun 8 11:53:51 2012 >> New Revision: 236744 >> URL: http://svn.freebsd.org/changeset/base/236744 >> >> Log: >> Add (experimentally) a function to the sleepqueue(9) KPI >> sleepq_set_timeout_bt() in which the timeout may be specified in terms >> of bintime rather than ticks, and which takes advantage of the new >> precision capabilities of the callout subsystem. >> >> Modify the kern_nanosleep() function so that it may rely on >> sleepq_set_timeout_bt() rather than tsleep(). >> >> Modified: >> projects/calloutng/sys/kern/kern_time.c >> projects/calloutng/sys/kern/subr_sleepqueue.c >> projects/calloutng/sys/sys/sleepqueue.h >> >> Modified: projects/calloutng/sys/kern/kern_time.c >> ============================================================================== >> --- projects/calloutng/sys/kern/kern_time.c Fri Jun 8 11:40:30 2012 (r236743) >> +++ projects/calloutng/sys/kern/kern_time.c Fri Jun 8 11:53:51 2012 (r236744) >> @@ -43,6 +43,7 @@ __FBSDID("$FreeBSD$"); >> #include <sys/resourcevar.h> >> #include <sys/signalvar.h> >> #include <sys/kernel.h> >> +#include <sys/sleepqueue.h> >> #include <sys/syscallsubr.h> >> #include <sys/sysctl.h> >> #include <sys/sysent.h> >> @@ -352,37 +353,40 @@ static int nanowait; >> int >> kern_nanosleep(struct thread *td, struct timespec *rqt, struct timespec *rmt) >> { >> - struct timespec ts, ts2, ts3; >> - struct timeval tv; >> - int error; >> + struct timespec ts; >> + struct bintime bt, bt2, tmp; >> + int catch = 0, error; >> >> if (rqt->tv_nsec < 0 || rqt->tv_nsec >= 1000000000) >> return (EINVAL); >> if (rqt->tv_sec < 0 || (rqt->tv_sec == 0 && rqt->tv_nsec == 0)) >> return (0); >> - getnanouptime(&ts); >> - timespecadd(&ts, rqt); >> - TIMESPEC_TO_TIMEVAL(&tv, rqt); >> + binuptime(&bt); >> + timespec2bintime(rqt, &tmp); >> + bintime_add(&bt,&tmp); >> for (;;) { >> - error = tsleep(&nanowait, PWAIT | PCATCH, "nanslp", >> - tvtohz(&tv)); >> - getnanouptime(&ts2); >> - if (error != EWOULDBLOCK) { >> - if (error == ERESTART) >> - error = EINTR; >> - if (rmt != NULL) { >> - timespecsub(&ts, &ts2); >> - if (ts.tv_sec < 0) >> - timespecclear(&ts); >> - *rmt = ts; >> - } >> + sleepq_lock(&nanowait); >> + sleepq_add(&nanowait, NULL, "nanslp", PWAIT | PCATCH, 0); >> + sleepq_set_timeout_bt(&nanowait,bt); >> + error = sleepq_timedwait_sig(&nanowait,catch); >> + binuptime(&bt2); >> + if (catch) { >> + if (error != EWOULDBLOCK) { >> + if (error == ERESTART) >> + error = EINTR; >> + if (rmt != NULL) { >> + tmp = bt; >> + bintime_sub(&tmp, &bt2); >> + bintime2timespec(&tmp,&ts); >> + if (ts.tv_sec < 0) >> + timespecclear(&ts); >> + *rmt = ts; >> + } >> return (error); >> + } >> } >> - if (timespeccmp(&ts2, &ts, >=)) >> + if (bintime_cmp(&bt2, &bt, >=)) >> return (0); >> - ts3 = ts; >> - timespecsub(&ts3, &ts2); >> - TIMESPEC_TO_TIMEVAL(&tv, &ts3); >> } >> } >> >> >> Modified: projects/calloutng/sys/kern/subr_sleepqueue.c >> ============================================================================== >> --- projects/calloutng/sys/kern/subr_sleepqueue.c Fri Jun 8 11:40:30 2012 (r236743) >> +++ projects/calloutng/sys/kern/subr_sleepqueue.c Fri Jun 8 11:53:51 2012 (r236744) >> @@ -361,6 +361,22 @@ sleepq_add(void *wchan, struct lock_obje >> * Sets a timeout that will remove the current thread from the specified >> * sleep queue after timo ticks if the thread has not already been awakened. >> */ >> +void >> +sleepq_set_timeout_bt(void *wchan, struct bintime bt) >> +{ >> + >> + struct sleepqueue_chain *sc; >> + struct thread *td; >> + >> + td = curthread; >> + sc = SC_LOOKUP(wchan); >> + mtx_assert(&sc->sc_lock, MA_OWNED); >> + MPASS(TD_ON_SLEEPQ(td)); >> + MPASS(td->td_sleepqueue == NULL); >> + MPASS(wchan != NULL); >> + callout_reset_bt_on(&td->td_slpcallout, bt, sleepq_timeout, td, PCPU_GET(cpuid)); >> +} >> + > > For this, I'd rather prefer that you patch sleepq_set_timeout() directly to be: > void sleepq_set_timeout(void *wchan, int timo, struct bintime *bt);u > > Then, if you pass a NULL ptr to bt the 'timo' is used, otherwise bt is > given preference in the logic. You will need to patch the current few > callers of sleepq_set_timo() to get NULL, but it is a small patch. > I would really like that you do the same also in the callout KPI, > possibly, because this avoids a lot of code duplication. > > Attilio > > > -- > Peace can only be achieved by understanding - A. Einstein Attilio, I agree with you about the few clients of sleepq_set_timeout(), and I may change it easily. About the callout_* KPI, if you refer to the recently added callout_reset_bt_on() function, I have some concerns. Right now, the number of consumers of callout_reset() or callout_reset_on() is a lot bigger than the one of sleepq_set_timeout() to consider a change, at least from my point of view. Moreover, differently from previous case, callout_reset_bt_on() doesn't duplicate code because I've moved the old code there and made callout_reset_on() a wrapper in which conversion is made and callout_reset_bt_on() is called. Davidehelp
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