Message-ID: <4C7D232D.6030802@2ndquadrant.com>
Date: Tue, 31 Aug 2010 11:43:41 -0400
From: Greg Smith <greg@2ndquadrant.com>
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To: Yeb Havinga <yebhavinga@gmail.com>
CC: Jose Ildefonso Camargo Tolosa <ildefonso.camargo@gmail.com>,
	"pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>
Subject: Re: Performance on new 64bit server compared to my 32bit
 desktop
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Yeb Havinga wrote:
> The rather wierd dip at 5 threads is consistent over multiple tries

I've seen that twice on 4 core systems now.  The spot where there's just 
one more thread than cores seems to be the worst case for cache 
thrashing on a lot of these servers.

How much total RAM is in this server?  Are all the slots filled?  Just 
filling in a spreadsheet I have here with sample configs of various 
hardware.

Yeb's results look right to me now.  That's what an AMD Phenom II X4 940 
@ 3.00GHz should look like.  It's a little faster, memory-wise, than my 
older Intel Q6600 @ 2.4GHz.  So they've finally caught up with that 
generation of Intel's stuff.  But my current desktop quad-core i860 with 
hyperthreading is nearly twice as fast in terms of memory access at 
every thread size.  That's why I own one of them instead of a Phenom II X4.

-- 
Greg Smith  2ndQuadrant US  Baltimore, MD
PostgreSQL Training, Services and Support
greg@2ndQuadrant.com   www.2ndQuadrant.us