Message-ID: <465081D6.1080306@tweakers.net>
Date: Sun, 20 May 2007 19:13:58 +0200
From: Arjen van der Meijden <acmmailing@tweakers.net>
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To: jlmarin <jlmarin@gmail.com>
CC: pgsql-performance@postgresql.org
Subject: Re: Diminishing bandwidth performance with multiple quad core X5355s
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On 14-5-2007 0:00 jlmarin wrote:
> I wanted to post this even if it's a bit late on the thread because
> right now I have exactly this kind of problem.
> We're trying to figure out if a dual-Quadcore (Xeon) will be better
> (cost/benefit wise) than a 4-way Opteron dualcore, for *our* program.

We've benchmarked the Sun Fire x4600 (with the older socket 939 cpu's) 
and compared it to a much cheaper dual quad core xeon X5355.

As you can see on the end of this page:
http://tweakers.net/reviews/674/8

The 4-way dual core opteron performs less (in our benchmark) than the 
2-way quad core xeon. Our benchmark does not consume a lot of memory, 
but I don't know which of the two profits most of that. Obviously it may 
well be that the Socket F opterons with support for DDR2 memory perform 
better, but we haven't seen much proof of that.
Given the cost of a 4-way dual core opteron vs a 2-way quad core xeon, 
I'd go for the latter for now. The savings can be used to build a system 
with heavier I/O and/or more memory, which normally yield bigger gains 
in database land.
For example a Dell 2900 with 2x X5355 + 16GB of memory costs about 7000 
euros less than a Dell 6950 with 4x 8220 + 16GB. You can buy an 
additional MD1000 with 15x 15k rpm disks for that... And I doubt you'll 
find any real-world database benchmark that will favour the 
opteron-system if you look at the price/performance-picture.

Of course this picture might very well change as soon as the new 
'Barcelona' quad core opterons are finally available.

> As you say, Opterons do definitely have a much better memory system.
> But then a 4-way mobo is WAY more expensive that a dual-socket one...

And it might be limited by NUMA and the relatively simple broadcast 
architecture for cache coherency.

Best regards,

Arjen van der Meijden