Re: Linux: more cores = less concurrency.

--- On Mon, 11/4/11, Joshua D. Drake <jd(at)commandprompt(dot)com> wrote:

> From: Joshua D. Drake <jd(at)commandprompt(dot)com>
> Subject: Re: [PERFORM] Linux: more cores = less concurrency.
> To: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>
> Cc: pgsql-performance(at)postgresql(dot)org, "Glyn Astill" <glynastill(at)yahoo(dot)co(dot)uk>
> Date: Monday, 11 April, 2011, 19:12
> On Mon, 11 Apr 2011 13:09:15 -0500,
> "Kevin Grittner"
> <Kevin(dot)Grittner(at)wicourts(dot)gov>
> wrote:
> > Glyn Astill <glynastill(at)yahoo(dot)co(dot)uk>
> wrote:
> > 
> >> The new server uses 4 x 8 core Xeon X7550 CPUs at
> 2Ghz
> > 
> > Which has hyperthreading.
> > 
> >> our current servers are 2 x 4 core Xeon E5320 CPUs
> at 2Ghz.
> > 
> > Which doesn't have hyperthreading.
> > 

Yep, off. If you look at the benchmarks I took, HT absoloutely killed it.

> > PostgreSQL often performs worse with hyperthreading
> than without.
> > Have you turned HT off on your new machine?  If
> not, I would start
> > there.
>
> And then make sure you aren't running CFQ.
>
> JD
>

Not running CFQ, running the no-op i/o scheduler.