From: Greg Smith <gsmith@gregsmith.com>
To: pgsql-performance@postgresql.org
Subject: Re: Background writer underemphasized ...
Date: Wed, 16 Apr 2008 15:55:51 -0400 (EDT)
Message-ID: <Pine.GSO.4.64.0804161546310.27404@westnet.com> (raw)
In-Reply-To: <20080416144335.04368b67.wmoran@collaborativefusion.com>
References: <480619CA.2080904@geizhals.at>
<20080416144335.04368b67.wmoran@collaborativefusion.com>
On Wed, 16 Apr 2008, Bill Moran wrote:
>> bgwriter_delay = 10000ms # 10-10000ms between rounds
>> bgwriter_lru_maxpages = 1000 # 0-1000 max buffers written/round
> Have you watched closely under load to ensure that you're not seeing a
> huge performance hit every 10s when the bgwriter kicks off?
bgwriter_lru_maxpages = 1000 means that any background writer pass can
write at most 1000 pages = 8MB. Those are buffered writes going into the
OS cache, which it will write out at its own pace later. That isn't going
to cause a performance hit when it happens.
That isn't the real mystery though--where's the RAID5 rant I was expecting
from you?
--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD
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To: pgsql-performance@postgresql.org
Cc: gsmith@gregsmith.com
Subject: Re: Background writer underemphasized ...
In-Reply-To: <Pine.GSO.4.64.0804161546310.27404@westnet.com>
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