Re: limiting hint bit I/O

Robert Haas wrote:
> On Sat, Feb 5, 2011 at 4:31 PM, Bruce Momjian <bruce@momjian.us> wrote:
> > Uh, in this C comment:
> >
> > + ? ? ? ?* or not we want to take the time to write it. ?We allow up to 5% of
> > + ? ? ? ?* otherwise-not-dirty pages to be written due to hint bit changes,
> >
> > 5% of what? ?5% of all buffers? ?5% of all hint-bit-dirty ones? ?Can you
> > clarify this in the patch?
> 
> 5% of buffers that are hint-bit-dirty but not otherwise dirty.  ISTM
> that's exactly what the comment you just quoted says on its face, but
> I'm open to some other wording you want to propose.

How about:
otherwise-not-dirty -> only-hint-bit-dirty

So 95% of your hint bit modificates are discarded if the pages is not
otherwise dirtied?  That seems pretty radical.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
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