Date: Thu, 15 Apr 2010 16:24:05 -0400
From: Alvaro Herrera <alvherre@commandprompt.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Josh Berkus <josh@agliodbs.com>, pgsql-performance@postgresql.org
Subject: Re: Autovaccum with cost_delay does not complete on one
	solaris 5.10 machine
Message-ID: <20100415202405.GL7259@alvh.no-ip.org>
References: <4BC76C9F.1020200@agliodbs.com>
	<20100415200056.GJ7259@alvh.no-ip.org>
	<16088.1271362441@sss.pgh.pa.us>
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Tom Lane wrote:
> Alvaro Herrera <alvherre@commandprompt.com> writes:
> > We don't call pollsys anywhere.  Something in Solaris must be doing it
> > under the hood.
> 
> pg_usleep calls select(), and some googling indicates that select() is
> implemented as pollsys() on recent Solaris versions.  So Josh's
> assumption that those are delay calls seems plausible.  But it shouldn't
> be sleeping after each page with normal cost_delay parameters, should it?

Certainly not ... The only explanation would be that the cost balance
gets over the limit very frequently.  So one of the params would have to
be abnormally high (vacuum_cost_page_hit, vacuum_cost_page_miss,
vacuum_cost_page_dirty).

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.