Re: tuning bgwriter in 8.4.2

On Feb 22, 2010, at 6:47 PM, Greg Smith wrote:

> Ben Chobot wrote:
>> Is it reading it correctly to say that the bgwriter probably wouldn't help much, because a majority of the dirty
pagesappear to be popular? 
>
> Yes.  The background writer cleaner process only does something useful if there are pages with low usage counts it
canevict.  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
workingset of data it never wants to evict unless it's for a checkpoint. 

Hm, my shared_buffers is already 10GB, but I'm using about 80GB for filesystem cache. Would a larger shared_buffers
makesense? I thought I read somewhere that 10GB is on the high end of the useful size for shared_buffers.