Date: Tue, 26 Oct 2004 16:09:50 +0200 From: =?iso-8859-2?q?S=B3awek_=AFak?= <zaks@prioris.mini.pw.edu.pl> To: Robert Watson <rwatson@freebsd.org> Cc: current@freebsd.org Subject: Re: Hard hangs on AMD64 with mpsafenet enabled Message-ID: <86vfcx7eq9.fsf@thirst.unx.era.pl> In-Reply-To: <Pine.NEB.3.96L.1041026125447.3203d-100000@fledge.watson.org> (Robert Watson's message of "Tue, 26 Oct 2004 13:00:51 %2B0100 (BST)") References: <Pine.NEB.3.96L.1041026125447.3203d-100000@fledge.watson.org>
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Robert Watson <rwatson@freebsd.org> writes:
> Thanks for the report -- I have some questions below that it would be
> helpful if you could answer.
>
> On Tue, 26 Oct 2004, [iso-8859-2] Sławek Żak wrote:
>
>> I've got a Sun V20z 2 cpu Opteron box. I experience hard hangs when
>> accessing NFS simulatneously from 2 processes (tested with parallel port
>> builds with /usr/ports mounted over NFS with
>> nosuid,nodev,soft,bg,intr). rpc.lockd and rpc.statd are both enabled for
>> NFS.
>
> From the above, can I assume that this is a problem on the NFS client, and
> that the NFS server is on another system reachable via a local area
> network?
Correct.
> When "hung", can the machine be pinged from another machine?
Haven't tried it. I will.
> From your subject line, it looks like you mean "when debug.mpsafenet=0,
> this doesn't happen". Is that a correct reading?
Yes, I've forgotten to add it, but followed up with another email.
> Could you try running with WITNESS and INVARIANTS enabled, and see if you
> get any specific warnings or assertion failures? A hard hang could imply
> a deadlock, which WITNESS would be able to report on. Other sources of
> hard hangs may be easier to debug with INVARIANTS and WITNESS enabled.
Ok.
> If possible, getting access to a serial console might make this problem
> significantly easier to debug.
I will try to make a cable for such access. Tomorrow morning.
>> I cannot also enter the debugger with C-M-ESC (no serial console at this
>> moment, sorry). When the system is running and I try to enter the debugger
>> on video console I get garbage on the screen and a reboot immediately
>> after. Scary stuff. I can't play with MP watchdog now (4 CPU box arrives in
>> two weeks).
>
> So when there isn't a problem and you try to enter the debugger on the
> video console, you get the garbage, or only when this problem is
> manifesting?
When the server is working fine. When it's hanging I cannot enter the
debugger.
/S
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