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 15:07:59 -0400
Message-ID: <8807.1282158479@sss.pgh.pa.us> (raw)
In-Reply-To: <4C6C2E4A.1010506@agliodbs.com>
References: <4C69827A.409@agliodbs.com>
<19969.1281986537@sss.pgh.pa.us>
<4C6C2B2B.9060501@agliodbs.com>
<8599.1282158010@sss.pgh.pa.us>
<4C6C2E4A.1010506@agliodbs.com>
Josh Berkus <josh@agliodbs.com> writes:
>> Rather, what you need to be thinking about is how
>> come vacuum seems to be making lots of pages dirty on only one of these
>> machines.
> This is an anti-wraparound vacuum, so it could have something to do with
> the hint bits. Maybe it's setting the freeze bit on every page, and
> writing them one page at a time?
That would explain all the writes, but it doesn't seem to explain why
your two servers aren't behaving similarly.
> Still don't understand the call to pollsys, even so, though.
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.
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: <8807.1282158479@sss.pgh.pa.us>
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