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Re: Two identical systems, radically different performance

From: Gavin Flower <GavinFlower(at)archidevsys(dot)co(dot)nz>
To: Craig James <cjames(at)emolecules(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Two identical systems, radically different performance
Date: 2012-10-08 23:52:28
Message-ID: 5073673C.10905@archidevsys.co.nz (view raw or flat)
Thread:
Lists: pgsql-performance
On 09/10/12 12:40, Craig James wrote:
> Nobody has commented on the hyperthreading question yet ... does it 
> really matter? The old (fast) server has hyperthreading disabled, and 
> the new (slower) server has hyperthreads enabled.
>
> If hyperthreading is definitely NOT an issue, it will save me a trip 
> to the co-lo facility.
>
> Thanks,
> Craig
>
> On Mon, Oct 8, 2012 at 3:29 PM, Craig James <cjames(at)emolecules(dot)com 
> <mailto:cjames(at)emolecules(dot)com>> wrote:
>
>     One mistake in my descriptions...
>
>     On Mon, Oct 8, 2012 at 2:45 PM, Craig James <cjames(at)emolecules(dot)com
>     <mailto:cjames(at)emolecules(dot)com>> wrote:
>
>         This is driving me crazy.  A new server, virtually identical
>         to an old one, has 50% of the performance with pgbench.  I've
>         checked everything I can think of.
>
>         The setups (call the servers "old" and "new"):
>
>         old: 2 x 4-core Intel Xeon E5620
>         new: 4 x 4-core Intel Xeon E5606
>
>
>     Actually it's not 16 cores.  It's 8 cores, hyperthreaded.
>     Hyperthreading is disabled on the old system.
>
>     Is that enough to make this radical difference?  (The server is at
>     a co-location site, so I have to go down there to boot into the
>     BIOS and disable hyperthreading.)
>
>     Craig
>
>
My latest development box (Intel Latest Core i7 3770K Ivy Bridge Quad 
Core with HT 3.4GHz) has hyperthreading - and it *_does_* make a 
significant difference.

Cheers,
Gavin

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