From: Tom Lane <tgl@sss.pgh.pa.us>
To: Josh Berkus <josh@agliodbs.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Return of the Solaris vacuum polling problem -- anyone remember this?
Date: Wed, 18 Aug 2010 17:02:49 -0400
Message-ID: <13390.1282165369@sss.pgh.pa.us> (raw)
In-Reply-To: <4C6C431B.9010406@agliodbs.com>
References: <4C69827A.409@agliodbs.com>
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<4C6C2B2B.9060501@agliodbs.com>
<8599.1282158010@sss.pgh.pa.us>
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<8807.1282158479@sss.pgh.pa.us>
<4C6C431B.9010406@agliodbs.com>
Josh Berkus <josh@agliodbs.com> writes:
>> Most likely that's the libc implementation of the select()-based sleeps
>> for vacuum_cost_delay. I'm still suspicious that the writes are eating
>> more cost_delay points than you think.
> Tested that. It does look like if I increase vacuum_cost_limit to 10000
> and lower vacuum_cost_page_dirty to 10, it reads 5-7 pages and writes
> 2-3 before each pollsys. The math seems completely wrong on that,
> though -- it should be 50 and 30 pages, or similar.
I think there could be a lot of cost_delay points getting expended
without any effects visible at the level of strace. Maybe try fooling
with vacuum_cost_page_hit and vacuum_cost_page_miss, too.
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, josh@agliodbs.com
Subject: Re: Return of the Solaris vacuum polling problem -- anyone remember this?
In-Reply-To: <13390.1282165369@sss.pgh.pa.us>
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