Re: Bgwriter behavior

Simon Riggs wrote:
> On Mon, 2004-12-27 at 22:21, Bruce Momjian wrote:
> > Should we consider at least adjusting the meaning of bgwriter_percent?
>
> Yes. As things stand, this is the only change that seems safe.
>
> Here's a very short patch that implements this change within BufferSync
> in bufmgr.c
>
> - No algorithm changes
> - No error message changes
> - Only change is the call to StrategyDirtyBufferList is made using the
> maximum number of buffers that will be cleaned, rather than uselessly
> trawling through all of shared_buffers
>
> This changes the meaning of bgwriter_percent from "percent of dirty
> buffers" to "percent of shared_buffers". The default settings of 1% of
> 1000 buffers gives up to 10 dirty block writes every 250ms
>
> Benefit: allows performance tuning by increases options for setting
> bgwriter_delay which would otherwise have an ineffectually high minimum
> setting
>
> Risk: low
>
> 1-line doc patch to follow, if this is approved.

I am not objecting to the patch, but what value is there in having both
bgwriter_percent and bgwriter_maxpages?  Seems both are redundant and
that one would be enough.

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