Re: buffercache/bgwriter

From: Uwe Bartels <uwe(dot)bartels(at)gmail(dot)com>
To: Jochen Erwied <jochen(at)pgsql-performance(dot)erwied(dot)eu>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: buffercache/bgwriter
Date: 2011-03-23 13:39:55
Message-ID: AANLkTinKDF5UgA6UxfZ4d9cAOOamh8iwK9o7STkU0nZ7@mail.gmail.com
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Hi Jochen,

yes, I had that impression too.
But it is running. ...And has almost no effect. I changed all parameter to
the most aggressive, but....
Before I restarted the server I had a percentage of writes by the bgwriter
of less that 1 percent.

postgres=# select name,setting from pg_settings where name like 'bgw%';
name | setting
-------------------------+---------
bgwriter_delay | 10
bgwriter_lru_maxpages | 1000
bgwriter_lru_multiplier | 10

Best...
Uwe

Uwe Bartels
Systemarchitect - Freelancer
mailto: uwe(dot)bartels(at)gmail(dot)com
tel: +49 172 3899006
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website: http://www.uwebartels.com

On 23 March 2011 14:19, Jochen Erwied <jochen(at)pgsql-performance(dot)erwied(dot)eu>wrote:

> Wednesday, March 23, 2011, 1:51:31 PM you wrote:
>
> [rearranged for quoting]
>
> > background writer stats
> > checkpoints_timed | checkpoints_req | buffers_checkpoint | buffers_clean
> |
> > maxwritten_clean | buffers_backend | buffers_alloc
> >
> -------------------+-----------------+--------------------+---------------+------------------+-----------------+---------------
> > 3 | 0 | 99754 | 0
> > | 0 | 115307 | 246173
> > (1 row)
>
> buffers_clean = 0 ?!
>
> > But I don't understand how postgres is unable to fetch a free buffer.
> > Does any body have an idea?
>
> Somehow looks like the bgwriter is completely disabled. How are the
> relevant settings in your postgresql.conf?
>
>
> --
> Jochen Erwied | home: jochen(at)erwied(dot)eu +49-208-38800-18, FAX:
> -19
> Sauerbruchstr. 17 | work: joe(at)mbs-software(dot)de +49-2151-7294-24, FAX:
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> D-45470 Muelheim | mobile: jochen(dot)erwied(at)vodafone(dot)de
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>
>

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