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Date:      Thu, 24 Jul 2008 13:37:21 +0100 (BST)
From:      Robert Watson <rwatson@FreeBSD.org>
To:        Mikhail Teterin <mi+mill@aldan.algebra.com>
Cc:        Kris Kennaway <kris@FreeBSD.org>, questions@FreeBSD.org, Jeremy Chadwick <koitsu@FreeBSD.org>, stable@FreeBSD.org
Subject:   Re: "sleeping without queue" ?
Message-ID:  <20080724133555.P63347@fledge.watson.org>
In-Reply-To: <48861448.7020708@aldan.algebra.com>
References:  <4885F2A6.5020204@aldan.algebra.com> <4885FCE5.1060507@FreeBSD.org> <48860725.9050808@aldan.algebra.com> <20080722161958.GA11139@eos.sc1.parodius.com> <48860E8C.6050400@FreeBSD.org> <48860EF6.2040007@aldan.algebra.com> <48861284.1050706@FreeBSD.org> <48861448.7020708@aldan.algebra.com>

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On Tue, 22 Jul 2008, Mikhail Teterin wrote:

> Kris Kennaway ???????(??):
>> Mikhail Teterin wrote:
>>> Kris Kennaway ???????(??):
>>>> Well, I mean kernel backtrace.
>>> Can I obtain that remotely and without restarting/panicking the box? 
>>> Thanks,
>> kgdb on /dev/mem or procstat
>   root@aldan:~ (107) kgdb /boot/kernel/kernel /dev/mem
>   [...]
>   (kgdb) bt
>   #0  0x0000000000000000 in ?? ()
>   Error accessing memory address 0x0: Bad address.
>
> Even less luck with procstat:
>
>   root@aldan:~ (108) locate procstat
>   root@aldan:~ (109) procstat
>   procstat: ???????? ???????.
>   root@aldan:~ (110) man procstat
>   No manual entry for procstat
>
> I'm sorry, but you'll need to be more specific. What should I type? Thanks,

Assuming you're using 7.0 or an older 7-STABLE: procstat(1) appeared after 7.0 
was released, but should be there if you slide forward on 7-STABLE.  You can 
use "procstat -k pid" to see kernel stack traces for kernel threads working on 
behalf of the process.  Depending on the level of detail you require, you can 
use -kk to also list function offsets inside the kernel, but the results are a 
bit harder to read.

Robert N M Watson
Computer Laboratory
University of Cambridge



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