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Re: hyperthreaded cpu still an issue in 8.4?

From: Dave Youatt <dave(at)meteorsolutions(dot)com>
To: Matthew Wakeling <matthew(at)flymine(dot)org>
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 18:42:16
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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

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.

:-) there's also this interconnect thingie between sockets, cores and
memory. Nehalem has a new one (for Intel), integrated memory controller,
that is.  And a new on-chip cache organization.

 I'm still betting on the interconnect(s), particularly for
bandwidth-intensive, data pumping server apps.  And it looks like the
other new interconnect ("QuickPath") plays well w/the integrated memory
controller for multi-socket systems.

Greg, in your spare time...  Also, curious how Nehalem compares w/AMD
Phenom II, esp the newer ones w/multi-lane(?) HT

And apologies to the list for straying off topic a bit.


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Subject: Re: hyperthreaded cpu still an issue in 8.4?
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Subject: really stupid question about checkpointing

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