Re: Disk I/O system hang on 5.4-RELEASE-p8 i386

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From
Greg Rivers <gcr+freebsd-stable@tharned.org>
Date
24 Feb 2006 00:13:32
Subject
Re: Disk I/O system hang on 5.4-RELEASE-p8 i386
Message-ID
20060223175345.U12100@w10.sac.fedex.com

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On Thu, 23 Feb 2006, Kris Kennaway wrote:

>> I believe this issue has made it onto the show-stopper list for
>> 6.1-RELEASE and is being actively worked on.
>
> It's on the todo list, but I don't think it's being worked on yet.
> The main problem is that we need a way to reproduce it on command.
> I'd forgotten that snapshots are involved, so maybe it's just a matter
> of running lots of mksnap_ffs while I/O is in progress.
>
> kris
>

It happens with or without snapshots, but snapshots are a lot more likely
to make it happen. In my case, approximately 1 in 3 snapshots will do it.
Without snapshots, I get a deadlock about every ten days in a population
of three hosts.

Tor Egge and Don Lewis were kind enough to work with me off-list for a bit
last December. They analyzed several of the core files I produced and I
think they have a fair understanding of what the problems are. But I
wouldn't presume to put words in their mouths; perhaps they'll give us an
update. I see from the todo list that Tor may already be working on the
deadlock for amd64.

I'm at the disposal of anyone who's willing to look into this further.

--
Greg


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