From: Peter Eisentraut <peter_e@gmx.net>
To: Huang, Suya <Suya.Huang@au.experian.com>
To: pgsql-admin@postgresql.org <pgsql-admin@postgresql.org>
Subject: Re: How to interpret view pg_stat_bgwriter
Date: Wed, 17 Sep 2014 16:40:44 -0400
Message-ID: <5419F1CC.8060309@gmx.net> (raw)
In-Reply-To: <D83E55F5F4D99B4A9B4C4E259E6227CD01EBFA82@AUX1EXC02.apac.experian.local>
References: <D83E55F5F4D99B4A9B4C4E259E6227CD01EBFA82@AUX1EXC02.apac.experian.local>
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On 9/16/14 2:42 AM, Huang, Suya wrote:
> # checkpoints_req is much bigger than checkpoints_timed, suggest that I
> may increase checkpoint_segments in our system
That's not strictly necessary, but personally I think both of those
settings are too low for you.
> #maxwritten_clean is high, suggests increase bgwriter_lru_maxpages
Yes.
> # buffers_backend is much smaller than buffers_alloc, suggests
> increasing bgwriter_lru_maxpages, bgwriter_lru_multiplier, and
> decreasing bgwriter_delay.
You should rather compare buffers_backend against buffers_checkpoint.
Also consider graphing these quantities over time so you can see how
different workloads affects the results and what the effects of your
tuning are.
Also turn on log_checkpoints and look at the sync times. In my
experience that dominates all the bgwriter tuning.
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To: pgsql-admin@postgresql.org
Cc: peter_e@gmx.net, Suya.Huang@au.experian.com
Subject: Re: How to interpret view pg_stat_bgwriter
In-Reply-To: <5419F1CC.8060309@gmx.net>
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