Stability problems with 7-stable (after 7.1 -> 7.2 -> 7-stable)

[Alexander Leidinger]

Quoting Boris Samorodov <bsam at ipt.ru> (from Thu, 17 Dec 2009 20:55:44 +0300):

> Ivan Voras <ivoras at freebsd.org> writes:
>> Alexander Leidinger wrote:
>>> Hi,
>>>
>>> please CC me on replies.
>
> Seems you were not CCed...

I'm now subscribed to stable@, thanks for forwarding this.

>>> I have a system which was at 7.1-pX. After the update to 7.2-p5 it
>>> started to exhibit deadlocks after some minutes of uptime.
>>>
>>> With 7.1 (generic kernel) it was running fine, with 7.2 generic the
>>> problems started directly.
>>>
>>> The system is now at 7-stable with a custom kernel
>>> (http://www.Leidinger.net/test/ALCATRAZ), basically generic without
>>> unneeded drivers plus witness/invariants/sw-watchdog.
>>>
>>> The system is an AMD Dual Core with NVidia MCP61 chipset
>>> (http://www.Leidinger.net/test/dmesg.alcatraz), 2 GB RAM, 2
>>> harddisks and FreeBSD 32bit install.
>>
>> Some generic things to try:
>> 	- did you monitor the system with something (top or systat
>> -vm) to see if there is something unusual, like interrupt storms?

When I had the initial problems, I asked for a KVM-switch to be  
connected to the system (not a free service). In SU mode I didn't see  
any problem. When starting the system but not the jails, I didn't see  
any problem (cvsup/buildworld/...). When I started the jails, I  
started to see the problems.

>> 	- no physical access is a problem; If you do manage it, I'd
>> say try running single user for some time with systat -vm just to see
>> what happens.

This is not an option now.

>> I would not trust ZFS in 7-stable since it lags a bit behind patches
>> done to 8 but 7.2 should be fine - at least I don't have any such
>> problems with it (though no AMD boxes to test them with it).

Ivan, the system started out to be without ZFS, just after I started  
to see deadlocks I switched to ZFS. This _improved_ the situation. Now  
the system survives between 3h and about 11h without a deadlock. If I  
run every 5 minutes a script which logs 4 text lines to the root (UFS)  
and runs 3x sync + sleep 5 + 3x sync the frequency of deadlocks  
increases.

>> If you haven't updated your ZFS pools, I'd suggest reverting back to
>> 7.1, then building or downloading an 8.0 kernel and try it with 7.1
>> userland (reboot -k ...) simply to see if it helps.

IIRC there where KBI changes (ifconfig?) which prevents me to go back  
to 7.1 without access to the console. As this is a production machine  
(it hosts not only my blog/website/mails, but stuff from other persons  
too), the goal is to stabilize this system now.

Kib analyzed 2 crashdumps I had (watchdog triggered) and he thinks  
they are because of ZFS deadlocks. So the initial problem (without  
ZFS) is not know yet, but this info will hopefully allow to stabilize  
the system further (see also my mail about at least 57 unmerged ZFS  
patches).

Bye,
Alexander.

-- 
Universities are places of knowledge.  The freshman each bring a little
in with them, and the seniors take none away, so knowledge accumulates.

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