From: Tim Allen <tim@proximity.com.au>
To: Jeff Trout <threshar@torgo.978.org>
Cc: pgsql-performance@postgresql.org
Subject: Re: SAN performance mystery
Date: Mon, 19 Jun 2006 16:12:07 +1000
Message-ID: <44964037.6060605@proximity.com.au> (raw)
In-Reply-To: <922914D7-46ED-4623-905A-C56058551905@torgo.978.org>
References: <4491D61B.9040507@proximity.com.au>
<449275A5.5090503@proximity.com.au>
<922914D7-46ED-4623-905A-C56058551905@torgo.978.org>
Jeff Trout wrote:
> On Jun 16, 2006, at 5:11 AM, Tim Allen wrote:
>> One curious thing is that some postgres backends seem to spend an
>> inordinate amount of time in uninterruptible iowait state. I found a
>> posting to this list from December 2004 from someone who reported
>> that very same thing. For example, bringing down postgres on the
>> customer box requires kill -9, because there are invariably one or
>> two processes so deeply uninterruptible as to not respond to a
>> politer signal. That indicates something not quite right, doesn't it?
>
> Sounds like there could be a driver/array/kernel bug there that is
> kicking the performance down the tube.
> If it was PG's fault it wouldn't be stuck uninterruptable.
That's what I thought. I've advised the customer to upgrade their kernel
drivers, and to preferably upgrade their kernel as well. We'll see if
they accept the advice :-|.
Tim
--
-----------------------------------------------
Tim Allen tim@proximity.com.au
Proximity Pty Ltd http://www.proximity.com.au/
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To: pgsql-performance@postgresql.org
Cc: tim@proximity.com.au, threshar@torgo.978.org
Subject: Re: SAN performance mystery
In-Reply-To: <44964037.6060605@proximity.com.au>
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