| From: | Greg Smith <greg(at)2ndquadrant(dot)com> |
|---|---|
| To: | Andy Colson <andy(at)squeakycode(dot)net> |
| Cc: | Craig Ringer <craig(at)postnewspapers(dot)com(dot)au>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: a heavy duty operation on an "unused" table kills my server |
| Date: | 2010-01-14 18:30:46 |
| Message-ID: | 4B4F62D6.7020104@2ndquadrant.com |
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| Thread: | |
| Lists: | pgsql-performance |
Andy Colson wrote:
> So if there is very little io, or if there is way way too much, then
> the scheduler really doesn't matter. So there is a slim middle ground
> where the io is within a small percent of the HD capacity where the
> scheduler might make a difference?
That's basically how I see it. There seem to be people who run into
workloads in the middle ground where the scheduler makes a world of
difference. I've never seen one myself, and suspect that some of the
reports of deadline being a big improvement just relate to some buginess
in the default CFQ implementation that I just haven't encountered.
--
Greg Smith 2ndQuadrant Baltimore, MD
PostgreSQL Training, Services and Support
greg(at)2ndQuadrant(dot)com www.2ndQuadrant.com
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