On Tue, 21 Aug 2007, ITAGAKI Takahiro wrote:

Does anyone have a way to measure the performance difference by
bgwriter_lru_xxx ? I have no performance results not only of the patch
but also of those parameters. I'd like to use those test cases to compare
manual and automatic tunings of lru parameters for 8.4.

The version of this patch I submitted at http://archives.postgresql.org/pgsql-patches/2007-05/msg00142.php puts statistics into the pg_stat_bgwriter structure so you can compare how much work is being done by the background writer vs. the backends. Even if there is no explicit change in the BW behavior, I would very much like to see that part get committed so people can actually tune more easily by hand using the stock PG in 8.3. Heikki didn't really like the way I passed that data around internally, but I never got a suggestion for doing it a better way I thought was an improvement.

Heikki's "Bgwriter strategies" thread used that to compare the various approaches, which I did quite a bit of as well but didn't bother publishing the results as they weren't any more interesting than his:

I have a set of scripts to automate pgbench to collect this data automatically and compare various settings. Now that I see all the big patches are settling down, I'll collect all that up and pass it along. I've been mulling over options here for a month now, and I'm not done with this patch yet; I'll take Bruce's message as a call to urgent action to finish and submit my final results ASAP.

* Greg Smith [EMAIL PROTECTED] http://www.gregsmith.com Baltimore, MD

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