Re: BGWriter latch, power saving
Peter Geoghegan <peter@2ndquadrant.com>
From: Peter Geoghegan <peter@2ndquadrant.com>
To: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>
Cc: PG Hackers <pgsql-hackers@postgresql.org>
Date: 2012-01-04T15:05:29Z
Lists: pgsql-hackers
Attachments
- bgwriter_latch.v2.patch (text/x-patch) patch v2
On 4 January 2012 07:24, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> wrote: > I think SetBufferCommitInfoNeedsSave() needs the same treatment as > MarkBufferDirty(). And it would probably be good to only set the latch if > the buffer wasn't dirty already. Setting a latch that's already set is fast, > but surely it's even faster to not even try. That seems reasonable. Revised patch is attached. > Yeah, I'd like to see a micro-benchmark of a worst-case scenario. I'm a bit > worried about the impact on systems with a lot of CPUs. If you have a lot of > CPUs writing to the same cache line that contains the latch's flag, that > might get expensive. Also reasonable, but I don't think that I'll get around to it until after the final commitfest deadline. -- Peter Geoghegan http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training and Services