scheduler (sched_4bsd) questions

[Julian Elischer]

Stephan Uphoff wrote:
> 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()?

interesting.. somehow when I applied that diff, the critical_enter disappeared?

>>
> 
> 
>>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();