Re: hyperthreaded cpu still an issue in 8.4? - Mailing list pgsql-performance

From Matthew Wakeling
Subject Re: hyperthreaded cpu still an issue in 8.4?
Date
Msg-id alpine.DEB.2.00.0907281037580.19493@aragorn.flymine.org
Whole thread Raw
In response to Re: hyperthreaded cpu still an issue in 8.4?  (Dave Youatt <dave@meteorsolutions.com>)
Responses Re: hyperthreaded cpu still an issue in 8.4?  (Greg Smith <gsmith@gregsmith.com>)
List 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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