svn commit: r236744 - in projects/calloutng/sys: kern sys

[Attilio Rao]

2012/6/8 Davide Italiano <davide at 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);

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