From: Greg Smith <gsmith@gregsmith.com>
To: pgsql-patches@postgresql.org
Subject: Re: Automatic adjustment of bgwriter_lru_maxpages
Date: Mon, 14 May 2007 09:57:28 -0400 (EDT)
Message-ID: <Pine.GSO.4.64.0705140946580.9478@westnet.com> (raw)
In-Reply-To: <46486705.3000507@enterprisedb.com>
References: <461E108D.6080709@enterprisedb.com>
<Pine.GSO.4.64.0705121926420.9615@westnet.com>
<20070514174531.71E0.ITAGAKI.TAKAHIRO@oss.ntt.co.jp>
<Pine.GSO.4.64.0705140926470.9478@westnet.com>
<46486705.3000507@enterprisedb.com>
On Mon, 14 May 2007, Heikki Linnakangas wrote:
> If it's safe to set it high, let's default it to infinity.
The maximum right now is 1000, and that would be a reasonable new default.
You really don't to write more than 1000 per interval anyway without
taking a break for checkpoints; the more writes you do at once, the higher
the chances are you'll have the whole thing stall because the OS makes you
wait for a write (this is not a theoretical comment; I've watched it
happen when I try to get the BGW doing too much).
If someone has so much activity that they're allocating more than that
during a period, they should shrink the delay instead. The kinds of
systems where 1000 isn't high enough for bgwriter_lru_maxpages are going
to be compelled to adjust these parameters anyway for good performance.
--
* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD
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To: pgsql-performance@postgresql.org
Cc: gsmith@gregsmith.com, pgsql-patches@postgresql.org
Subject: Re: Automatic adjustment of bgwriter_lru_maxpages
In-Reply-To: <Pine.GSO.4.64.0705140946580.9478@westnet.com>
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