[amd64] Instability worse than ever

[Scott Long]

Conrad J. Sabatier wrote:

> For the last couple of days, my amd64 box has taken to spontaneously
> rebooting.  No panic, no coredump, nothing in logs, just reboots.
> 
> These always seem to occur just as I'm clicking on something under
> GNOME.
> 
> Very mysterious!
> 

Do you have INVARIANTS turned on?  If you do, would you be able to
hook up a serial console and see what the kernel is saying?  Also,
a quick hack that might help you is to take either sched_4bsd.c or
sched_ule.c (depending on which you are using) and comment out the
call to maybe_preempt(td) in sched_add() like so:

+ if 0
   	if (maybe_preempt(td))
   		return;
+ endif

I think I understand most of the underlying problem with much of the
recent (and not so recent) instability, but I haven't come up with
an acceptable solution yet.  If anyone is interested in helping (code,
not test), please let me know.

Scott