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Re: hyperthreaded cpu still an issue in 8.4?

From: Matthew Wakeling <matthew(at)flymine(dot)org>
To: Dave Youatt <dave(at)meteorsolutions(dot)com>
Cc: Greg Smith <gsmith(at)gregsmith(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: hyperthreaded cpu still an issue in 8.4?
Date: 2009-07-28 09:45:01
Message-ID: alpine.DEB.2.00.0907281037580.19493@aragorn.flymine.org (view raw or flat)
Thread:
Lists: pgsql-performance
On Mon, 27 Jul 2009, Dave Youatt wrote:
> Greg, those are compelling numbers for the new Nehalem processors.
> Great news for postgresql.  Do you think it's due to the new internal
> interconnect...

Unlikely. Different threads on the same CPU core share their resources, so 
they don't need an explicit communication channel at all (I'm simplifying 
massively here). A real interconnect is only needed between CPUs and 
between different cores on a CPU, and of course to the outside world.

Scott's explanation of why SMT works better now is much more likely to be 
the real reason.

Matthew

-- 
 Ozzy:   Life is full of disappointments.
 Millie: No it isn't - I can always fit more in.

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