Date: Fri, 29 Jul 2016 13:17:42 -0700 From: John Baldwin <jhb@freebsd.org> To: gljennjohn@gmail.com Cc: current@freebsd.org Subject: Re: EARLY_AP_STARTUP hangs during boot Message-ID: <2732687.Cf9hD9SkSs@ralph.baldwin.cx> In-Reply-To: <20160728003131.1f67bb78@ernst.home> References: <20160516122242.39249a54@ernst.home> <1758017.P1iqL9uSnF@ralph.baldwin.cx> <20160728003131.1f67bb78@ernst.home>
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On Thursday, July 28, 2016 12:31:31 AM Gary Jennejohn wrote:
> Well, now I know that ULE is a prerequiste for EARLY_AP_STARTUP! I
> wasn't aware of that. I prefer BSD and that's the scheduler I did
> the first tests with.
>
> But with the ULE scheduler the system comes up all the way.
>
> It would be nice if the BSD scheduler could also be modified to
> work with EARLY_AP_STARTUP.
I wasn't able to reproduce your hang with 4BSD, but I think I see a
possible problem. Try this:
diff --git a/sys/kern/sched_4bsd.c b/sys/kern/sched_4bsd.c
index 7de56b6..d53331a 100644
--- a/sys/kern/sched_4bsd.c
+++ b/sys/kern/sched_4bsd.c
@@ -327,7 +327,6 @@ maybe_preempt(struct thread *td)
* - The current thread has a higher (numerically lower) or
* equivalent priority. Note that this prevents curthread from
* trying to preempt to itself.
- * - It is too early in the boot for context switches (cold is set).
* - The current thread has an inhibitor set or is in the process of
* exiting. In this case, the current thread is about to switch
* out anyways, so there's no point in preempting. If we did,
@@ -348,7 +347,7 @@ maybe_preempt(struct thread *td)
("maybe_preempt: trying to run inhibited thread"));
pri = td->td_priority;
cpri = ctd->td_priority;
- if (panicstr != NULL || pri >= cpri || cold /* || dumping */ ||
+ if (panicstr != NULL || pri >= cpri /* || dumping */ ||
TD_IS_INHIBITED(ctd))
return (0);
#ifndef FULL_PREEMPTION
@@ -1127,7 +1126,7 @@ forward_wakeup(int cpunum)
if ((!forward_wakeup_enabled) ||
(forward_wakeup_use_mask == 0 && forward_wakeup_use_loop == 0))
return (0);
- if (!smp_started || cold || panicstr)
+ if (!smp_started || panicstr)
return (0);
forward_wakeups_requested++;
--
John Baldwin
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