Re: Spin Lock sleep resolution

On Tue, 18 Jun 2013 10:09:55 +0300
Heikki Linnakangas <hlinnakangas(at)vmware(dot)com> wrote:

> On 02.04.2013 22:58, David Gould wrote:

> > I'll give the patch a try, I have a workload that is impacted by spinlocks
> > fairly heavily sometimes and this might help or at least give me more
> > information. Thanks!
>
> Did you ever get around to test this?
>
> I repeated these pgbench tests I did earlier:
>
> http://www.postgresql.org/message-id/5190E17B.9060804@vmware.com
>
> I concluded in that thread that on this platform, the TAS_SPIN macro
> really needs a non-locked test before the locked one. That fixes the big
> fall in performance with more than 28 clients.
...
> I wasn't expecting much of a gain from this, just wanted to verify that
> it's not making things worse. So looks good to me.

Thanks for the followup, and I really like your graph, it looks exactly
like what we were hitting. My client ended up configuring around it
and adding more hosts so the urgency to run more tests sort of declined,
although I think we still hit it from time to time.

If you would like to point me at or send me the latest flavor of the patch
it may be timely for me to test again. Especially if this is a more or less
finished version, we are about to roll out a new build to all these hosts
and I'd be happy to try to incorporate this patch and get some production
experience with it on 80 core hosts.

-dg

--
David Gould 510 282 0869 daveg(at)sonic(dot)net
If simplicity worked, the world would be overrun with insects.