Re: Return of the Solaris vacuum polling problem -- anyone remember this?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Josh Berkus <josh(at)agliodbs(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Return of the Solaris vacuum polling problem -- anyone remember this?
Date: 2010-08-18 21:02:49
Message-ID: 13390.1282165369@sss.pgh.pa.us
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers

Josh Berkus <josh(at)agliodbs(dot)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

In response to

Browse pgsql-hackers by date

  From Date Subject
Next Message Kevin Grittner 2010-08-18 21:21:05 Re: CommitFest 2009-07: Yay, Kevin! Thanks, reviewers!
Previous Message Peter Eisentraut 2010-08-18 20:59:27 Re: Progress indication prototype