Re: Postgresql locks up server - no response at all

On Wed, 2004-08-04 at 15:27 -0600, Scott Long wrote:
> Sven Willenberger wrote:
> 
> > On Wed, 2004-08-04 at 13:49 -0700, Kevin Oberman wrote:
> > 
> >>>Date: Wed, 4 Aug 2004 13:34:56 -0700
> >>>From: Jeremy Chadwick <freebsd_at_jdc.parodius.com>
> >>>Sender: owner-freebsd-current_at_freebsd.org
> >>>
> >>>I've seen this with our SuperMicro SuperServer 5013C-T, running mysqld.
> >>>Please note that the server is "heavily loaded" (note the quotes); usually
> >>>a load of around 0.50 to 1.00 at all times, with mysqld being the top
> >>>process.  Server runs all latest -CURRENT builds.
> >>>
> >>>Many people over in freebsd-threads mentioned this problem, and recommended
> >>>all sorts-of different workarounds.  I tried every one available to me,
> >>>except mucking with PREEMPTION (as I did not feel comfortable tinkering
> >>>with a random .h file on the box; seemed to be a kernel-related thing,
> >>>so I'd rather have just an "options" line for it -- I'm conditionally
> >>>lazy).
> >>
> >>Please note that PREEMPTION is now NOT enabled in CURRENT. scottl
> >>changed that a day or two ago because of all of these lock-ups. He and
> >>Julian are listed as working to isolate the problem. Scott believes it's
> >>in the scheduler. It's not specific to either ULE or 4BSD.
> >>
> >>So cvsup, rebuild the kernel and you should be fine.At least for a while.
> > 
> > 
> > Based on this and Jeremy C.'s response it would appear that I should
> > either try to upgrade my 5.2.1-P8 system to -CURRENT (which is scary
> > because of the vinum array - root is not mounted on a vinum device, but
> > the data directory is - will gvinum simply read this correctly? it is a
> > stripe+mirror array of 4 drives) or start from scratch and go back to
> > 4.10 (STABLE) for a while. I am assuming that the lockups I am seeing
> > were exacerbated by the PREEMPTION episodes of the past couple weeks? If
> > I choose the upgrade to -CURRENT, are there any caveats or
> > recommendations? (besides reading "/usr/src/UPDATING" which I do
> > religiously anyway)
> > 
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> 
> I'm a bit nervous with asking you to upgrade to -current.  PREEMPTION is
> practically disabled in 5.2.1 so upgrading has a low chance of fixing
> the problem except maybe by sheer luck.  The best action would be to
> get a crashdump.  If your system has an NMI button, then there are some
> trivial patches that will assist with this.  If not, then you might want
> to look at backporting the ichwd watchdog driver and letting that do a
> chip-assisted NMI.
> 
> In any case, finding out exactly what each CPU is doing at the time of
> the lockup is going to be vital.  The lockups that I've been able to
> reproduce happen when a TAILQ in the scheduler gets corrupted and
> resulting in one CPU spinning on the list forever with the scheduler
> lock held.  All other cpus then quickly grind to a halt while they wait
> for the sched lock to become free, which it never does.
> 

The case unfortunately does not have a button (although the mobo does
have an NMI header/jumper). Backporting the watchdog driver sounds
doable; other than downloading the sys/dev/ichwd directory from a
repository and adding "options ichwd" to my kernel config file, what
else would be needed? I am willing to try to get at least one crashdump
before I have to go back to a -STABLE setup or try something so I can
get some uptime on this box.