scheduler (sched_4bsd) questions

[Stephan Uphoff]

On Sun, 2004-10-03 at 17:39, Julian Elischer wrote:
> Stephan Uphoff wrote:
>   you didn't answer this question..
> 
> > 
> > 
> >>Where is the critical_enter that matches the extra critical_exit()
> >>you put in sched_switch()? I haven' been able to yet figure out how
> >>you don't get a double exit. but I've only looked for a few minutes.
> > 
> 
> ==== //depot/projects/nsched/sys/kern/sched_4bsd.c#58 - 
> /home/julian/p4/nsched/sys/kern/sched_4bsd.c ====
> @@ -844,6 +844,8 @@
>                          if (newtd == NULL || newtd->td_ksegrp != td->td_ksegrp)
>                                  slot_fill(td->td_ksegrp);
>                  }
> +               critical_exit();
> +               td->td_pflags &= ~TDP_OWEPREEMPT;
>          }
>          if (newtd) {
>                  /*
> 
> 
> where is the matching critical_enter()?
> 

>From Peter's unified diff:

RCS file: /home/ncvs/src/sys/kern/sched_4bsd.c,v
retrieving revision 1.65
diff -u -r1.65 sched_4bsd.c
--- sys/kern/sched_4bsd.c       16 Sep 2004 07:12:59 -0000      1.65
+++ sys/kern/sched_4bsd.c       2 Oct 2004 14:46:29 -0000
@@ -823,6 +823,7 @@
                TD_SET_CAN_RUN(td);
        else {
                td->td_ksegrp->kg_avail_opennings++;
+               critical_enter();
                if (TD_IS_RUNNING(td)) {
                        /* Put us back on the run queue (kse and all).
*/
                        setrunqueue(td, SRQ_OURSELF|SRQ_YIELDING);
@@ -834,6 +835,8 @@
                         */
                        slot_fill(td->td_ksegrp);
                }
+               critical_exit();
+               td->td_pflags &= ~TDP_OWEPREEMPT;
        }
        if (newtd == NULL)
                newtd = choosethread();