[no subject]

Hypertransport is a similar idea, a switched network of 1.5Gb/s between CPUs. 
  Each CPU has it's own 1.5Gbps pipe to any other CPU.  Only currently scales 
to 8P as far as I know.  So 4 Xeons share in a hub like fashion the one 800MHz 
pipe to each other.
Dow


Jeffrey B. Layton wrote:
> Bjorn Dittmer-Roche wrote:
> 
>> On Fri, 23 Apr 2004, Dow Hurst wrote:
>>
>>  
>>
>>> I've been looking at performance of Opterons vs Itaniums/Xeons.  The 
>>> more
>>> Opterons on the motherboard the better.  So, 4P and 8P boards are out 
>>> there
>>> now.  Microway or Aspen have 4P units.  A Russian company has created 
>>> the 8P
>>> unit.  The Intel stuff is limited on interprocessor communication by 
>>> a single
>>> pipe while the Opterons have a switch like interconnect with much higher
>>> bandwidth.  The Xeon's top out and get starved by the limited pipe 
>>> they have
>>> to talk thru.  It is a long term problem Intel has gotten around for 
>>> now by
>>> bumping up CPU GHz.
>>>
>>> So you get a real increase in performance on the right kind of code 
>>> on a 4P+
>>> motherboard. ;-)
>>>
>>> I know your not after that info.  I just wanted to blab about what 
>>> I've been
>>> researching....
>>>   
>>
>>
>> I'm interested! I know this has been a long standing problem for intel.
>> One of the big advantages for years of companies like Sun
>> and SGI has been their ability to scale processors. Do
>> you happen to know how well the Opterons compare to these vendors?
>>
> 
> Scale in what way? Opterons have a neat memory bus (Hypertransport).
> I've only heard of systems going to 8-way, but I've heard rumors of
> 16-way systems though. The SGIs have a slightly different architecture.
> The processors are in a "network" configuration, like a Fat-Tree or
> a ring (couldn't think of a better work than "network", but that's not
> the right term) instead of having all of the processors on a single MB.
> Not sure how they compare, but I personally view them as separate
> products (although I'd love to see a 16-way Opteron, but I don't think
> AMD has a 1642 ot 1644 - at least not yet).
> 
> I tested one of our CFD codes on Opteron (242's I think) and compared
> them to Xeons/2.4 (800 MHz bus I think). On our code, the Opterons
> were faster by about 90% compared to the Xeons. YMMV.
> 
> Enjoy!
> 
> Jeff
> 
> 
> 
> _______________________________________________
> Ale mailing list
> Ale at ale.org
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</pre>
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<ul><li><strong>References</strong>:
<ul>
<li><strong><a name="00988" href="msg00988.html">[ale] Suggestions for 64 bit dual Opteron motherboards</a></strong>
<ul><li><em>From:</em> runman at speedfactory.net (Greg)</li></ul></li>
<li><strong><a name="00993" href="msg00993.html">[ale] Suggestions for 64 bit dual Opteron motherboards</a></strong>
<ul><li><em>From:</em> dhurst at kennesaw.edu (Dow Hurst)</li></ul></li>
<li><strong><a name="01012" href="msg01012.html">[ale] Suggestions for 64 bit dual Opteron motherboards</a></strong>
<ul><li><em>From:</em> bjorn at sccs.swarthmore.edu (Bjorn Dittmer-Roche)</li></ul></li>
<li><strong><a name="01016" href="msg01016.html">[ale] Suggestions for 64 bit dual Opteron motherboards</a></strong>
<ul><li><em>From:</em> laytonjb at charter.net (Jeffrey B. Layton)</li></ul></li>
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