Re: limiting hint bit I/O - Mailing list pgsql-hackers

From Kevin Grittner
Subject Re: limiting hint bit I/O
Date
Msg-id 4D334A010200002500039688@gw.wicourts.gov
Whole thread Raw
In response to limiting hint bit I/O  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: limiting hint bit I/O  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
Robert Haas  wrote:
> I think you may be confused about what the patch does - currently,
> pages with hint bit changes are considered dirty, period.
> Therefore, they are written whenever any other dirty page would be
> written: by the background writer cleaning scan, at checkpoints,
> and when a backend must write a dirty buffer before reallocating it
> to hold a different page. The patch keeps the first of these and
> changes the second two
No, I understood that.  I'm just concerned that if you eliminate the
other two, we may be recomputing visibility based on clog often
enough to kill performance.
In other words, I'm asking that you show that the other two methods
aren't really needed for decent overall performance.
-Kevin


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