| From: | Glyn Astill <glynastill(at)yahoo(dot)co(dot)uk> |
|---|---|
| To: | Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> |
| Cc: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Linux: more cores = less concurrency. |
| Date: | 2011-04-11 19:42:46 |
| Message-ID: | 356731.11980.qm@web26005.mail.ukl.yahoo.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-performance |
--- On Mon, 11/4/11, Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com> wrote:
> Just FYI, in synthetic pgbench type benchmarks, a 48 core
> AMD Magny
> Cours with LSI HW RAID and 34 15k6 Hard drives scales
> almost linearly
> up to 48 or so threads, getting into the 7000+ tps
> range. With SW
> RAID it gets into the 5500 tps range.
>
I'll have to try with the synthetic benchmarks next then, but somethings definately going off here. I'm seeing no disk activity at all as they're selects and all pages are in ram.
I was wondering if anyone had any deeper knowledge of any kernel tunables, or anything else for that matter.
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.
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