Re: tuning bgwriter in 8.4.2 - Mailing list pgsql-general

From Greg Smith
Subject Re: tuning bgwriter in 8.4.2
Date
Msg-id 4B8333B8.2050502@2ndquadrant.com
Whole thread Raw
In response to Re: tuning bgwriter in 8.4.2  (Ben Chobot <bench@silentmedia.com>)
Responses Re: tuning bgwriter in 8.4.2
List pgsql-general
Ben Chobot wrote:
> Is it reading it correctly to say that the bgwriter probably wouldn't
> help much, because a majority of the dirty pages appear to be popular?

Yes.  The background writer cleaner process only does something useful
if there are pages with low usage counts it can evict.  You would need
to increase shared_buffers significantly before it's likely that would
happen.  Right now, 87% of your buffer cache has a usage count of 2 or
higher, which basically means it's filled with almost nothing but the
working set of data it never wants to evict unless it's for a checkpoint.

--
Greg Smith  2ndQuadrant US  Baltimore, MD
PostgreSQL Training, Services and Support
greg@2ndQuadrant.com   www.2ndQuadrant.us


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