Skip site navigation (1) Skip section navigation (2)

Re: I/O increase after upgrading to 8.3.5

From: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
To: "Alexander Staubo" <alex(at)bengler(dot)no>
Cc: "pgsql-performance" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: I/O increase after upgrading to 8.3.5
Date: 2009-02-13 17:35:29
Message-ID: (view raw or whole thread)
Lists: pgsql-performance
>>> Alexander Staubo <alex(at)bengler(dot)no> wrote: 
> Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov> wrote:
>> Could you show the non-commented lines from old and new
>> postgresql.conf files, please?
> Attached. The differences are not performance-related, as far as I
> can see, aside from the additional of "synchronous_commit = off".
You should definitely set effective_cache_size.
If you still see the problem after that, I suggest testing different
settings for:
Both the checkpoint process and the background writer changed quite a
bit, and these are the main knobs for tuning the new version.
It's possible that under 8.2 your hint bit writes were being combined
with other writes due to caching, and differences in the timings now
have the hint bit writes happening too long after the initial write to
get that benefit.  If that's the case, the counterintuitive step of
making PostgreSQL more aggressive about writing to the OS cache might
reduce your disk write I/O.  Making it less aggressive might allow
them to combine in the PostgreSQL buffers before making to the OS

In response to


pgsql-performance by date

Next:From: Chris BrowneDate: 2009-02-13 17:37:21
Subject: Re: scheduling autovacuum at lean hours only.
Previous:From: Tom LaneDate: 2009-02-13 17:20:58
Subject: Re: [PERFORM] GIST versus GIN indexes for intarrays

Privacy Policy | About PostgreSQL
Copyright © 1996-2015 The PostgreSQL Global Development Group