Re: Linux: more cores = less concurrency.

--- On Mon, 11/4/11, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> wrote:

> From: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>
> Subject: Re: [PERFORM] Linux: more cores = less concurrency.
> To: "Glyn Astill" <glynastill(at)yahoo(dot)co(dot)uk>
> Cc: "Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov>, "Joshua D. Drake" <jd(at)commandprompt(dot)com>, pgsql-performance(at)postgresql(dot)org
> Date: Monday, 11 April, 2011, 21:52
> On Mon, Apr 11, 2011 at 1:42 PM, Glyn
> Astill <glynastill(at)yahoo(dot)co(dot)uk>
> wrote:
>
> > A wild guess is something like multiple cores
> contending for cpu cache, cpu affinity, or some kind of
> contention in the kernel, alas a little out of my depth.
> >
> > It's pretty sickening to think I can't get anything
> else out of more than 8 cores.
>
> Have you tried running the memory stream benchmark Greg
> Smith had
> posted here a while back?  It'll let you know if
> you're memory is
> bottlenecking.  Right now my 48 core machines are the
> king of that
> benchmark with something like 70+Gig a second.
>

No I haven't, but I will first thing tomorow morning. I did run a sysbench memory write test though, if I recall correctly that gave me somewhere just over 3000 Mb/s