Horton

Re: Spread checkpoint sync

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>, Itagaki Takahiro <itagaki.takahiro@gmail.com>, Greg Smith <greg@2ndquadrant.com>, Ron Mayer <rm_pg@cheapcomplexdevices.com>, Josh Berkus <josh@agliodbs.com>, pgsql-hackers@postgresql.org
Date: 2011-01-31T17:11:24Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Add new buffers_backend_fsync field to pg_stat_bgwriter.

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