Re: Spread checkpoint sync

Robert Haas <robertmhaas@gmail.com> writes:
> On Mon, Jan 31, 2011 at 11:51 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I wonder whether it'd be useful to keep track of the total amount of
>> data written-and-not-yet-synced, and to issue fsyncs often enough to
>> keep that below some parameter; the idea being that the parameter would
>> limit how much dirty kernel disk cache there is. �Of course, ideally the
>> kernel would have a similar tunable and this would be a waste of effort
>> on our part...

> It's not clear to me how you'd maintain that information without it
> turning into a contention bottleneck.

What contention bottleneck?  I was just visualizing the bgwriter process
locally tracking how many writes it'd issued.  Backend-issued writes
should happen seldom enough to be ignorable for this purpose.
        regards, tom lane