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Re: Performance on new 64bit server compared to my 32bit desktop

From: Greg Smith <greg(at)2ndquadrant(dot)com>
To: Scott Carey <scott(at)richrelevance(dot)com>
Cc: Philippe Rimbault <primbault(at)edd(dot)fr>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>
Subject: Re: Performance on new 64bit server compared to my 32bit desktop
Date: 2010-08-30 15:15:31
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
Scott Carey wrote:
> The 2427 should do 12.8 GB/sec theoretical peak (dual channel 800Mhz DDR2) per processor socket (so 2x that if multithreaded and 2 Sockets).
> A Nehalem will do ~2x that (triple channel, 1066Mhz) and is also significantly faster clock for clock.
> But a Core2 based Xeon on Socket 775 at 1066Mhz FSB?  Nah... its theoretical peak bandwidth is 33% more and real world no more than 40% more.
> The E7500 is basically the end of line Core2 before Nehalem based processors took over.

Ah...from its use of DDR3, I thought that the E7500 was a low-end 
Nehalem.  Now I see that you're right, that it's actually a high-end 
Wolfdale.  So that does significantly decrease the margin between the 
two I'd expect.  I agree with your figures, and that this may be back to 
looking a little fishy.

The other thing I normally check is whether one of the two systems has 
more aggressive power management turned on.  Easiest way to tell on 
Linux is look at /proc/cpuinfo , and see if the displayed processor 
speed is much lower than the actual one.  Many systems default to 
something pretty conservative here, and don't return up to full speed 
nearly fast enough for some benchmark tests.

> This isn't an older Opteron, its 6 core, 6MB L3 cache "Istanbul".  Its not the newer stuff either.   

Everything before Magny Cours is now an older Opteron from my 
perspective.  They've caught up with Intel again with the release of 
those.  Everything from AMD that's come out ever since Intel Nehalem 
products started shipping in quantity (early 2009) have been marginal 
products until the new M-C, and their early Quad-core stuff was pretty 
terrible too.  So in my head I'm lumping AMD's Budapest, Shanghai, and 
Istanbul product lines all into a giant "slow compared to Intel during 
the same period" bin in my head.  Fine for databases with lots of 
clients, not so good at executing single queries quickly.

Greg Smith  2ndQuadrant US  Baltimore, MD
PostgreSQL Training, Services and Support

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