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Date:      Wed, 17 Dec 2008 14:15:44 -0500
From:      Paul MacKenzie <bsdlist@cogeco.ca>
To:        freebsd-stable@freebsd.org
Subject:   Re: 7.1-PRERELEASE: arcmsr write performance problem
Message-ID:  <49494FE0.4040400@cogeco.ca>
In-Reply-To: <200812161556.mBGFuB7n089368@lava.sentex.ca>
References:  <2515BCEE3A2F4CBA8FFB9F1C052924AA@jmlaptop> <4934CB77.30906@transactionware.com> <494698E4.2070406@cogeco.ca> <200812151900.mBFJ0Jom084267@lava.sentex.ca> <4946B6EF.5080806@cogeco.ca> <200812152010.mBFKAlZf084580@lava.sentex.ca> <4946BDB1.8060208@cogeco.ca> <200812152035.mBFKZkj4084689@lava.sentex.ca> <4946DA2F.7090508@cogeco.ca> <200812161556.mBGFuB7n089368@lava.sentex.ca>

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> Is the high load average simply a function of processes blocking on
> network io ? On our av/spam scanners for example show a high load avg
> because there are many processes waiting on network io to complete
> (e.g. talking to RBL lists, waiting for DCC servers to complete etc)
>
> Also, is it really related to the arcmsr driver ? i.e. if you did the
> same tasks on a single IDE drive, is the performance profile going to
> be the same ?
>
>         ---Mike
>
I wondered if possibly my problem is related to this issue 104406?

[ufs] Processes get stuck in "ufs" state under persistent CPU load

http://www.freebsd.org/cgi/query-pr.cgi?pr=104406&cat=

As the processes do get stuck in the ufs mode from what I can tell.

I am going to be replacing the RAID card tomorrow to make sure it is not
the card despite the lack of errors.

If so I wondered if there was any way to quickly determine via
programming which process is stuck and  to get it unstuck as a temporary
workaround? The problem reports mentions using  'kill
-STOP' and continued with 'kill -CONT', which allows other processes to
access the filesystem (until another such failure occurs).

I just need to be able to determine which process is the one stuck in a
relatively easy manner.

Thanks,

Paul



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