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Topic Title: Direct Connect Architecture?
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Created On: 05/19/2004 07:55 PM
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 05/19/2004 07:55 PM
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snorre
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Joined: 10/10/2003

Can someone please explain to me what this means?

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My [i' ">http://forums.amd.com/index.php?showtopic=2208 8^)
 05/19/2004 10:56 PM
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OrangesAway
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Direct Connect Architecture is a marketting term AMD started recently using

According to this link' ">http://www.amd.com/us-en/Proce...,00.html#directconnect:

QUOTE Direct Connect Architecture
Addresses and helps reduce the real challenges and bottlenecks of system architectures
Memory is connected directly to the CPU thereby increasing memory latency performance
I/O is directly connected to the CPU for more balanced throughput and I/O
CPUs are connected directly to CPUs allowing for more linear symmetrical multiprocessing


More or less refers to the Hypertransport and on board memory controller. Better than using "glueless processor interconnect", which might confuse even more people
 05/20/2004 06:18 PM
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snorre
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Thanks for clearing this up

I maybe thought this was a new feature that has been added to the AMD64 instruction set of the new Opteron x50 processors according to this' ">http://www.amd.com/us-en/Corpo..._104_543~85125,00.html:

QUOTE “Our newest models of the AMD Opteron processor feature Direct Connect Architecture, which supplies benefits and system advantages well beyond extending the instruction set,” said Marty Seyer, vice president and general manager of the Microprocessor Business Unit, AMD.

The only problem I see with this new marketing term is that it can also easily be confused with the Direct Connected Processor (DCP) Architecture of Cray's XD1 system:
http://www.cray.com/temp/products/systems/xd1/dcp.html' ">http://www.cray.com/temp/products/systems/xd1/dcp.html

Or maybe this is what AMD intended?

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 05/21/2004 10:25 AM
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ZapWizard
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Well their system works the same way:

QUOTE Cray's implementation of the DCP architecture optimizes message-passing applications by directly linking processors to each other through a high performance interconnect fabric, eliminating shared memory contention and PCI bus bottlenecks.


What direct connect on a CPU means is that the I/O Bus links memory, cache, hypertransport and the CPU Core together.

If you run two or more CPUs they can "direct connect" to each other.
This means via hypertransport they can connecto to each other and use eachother's memory, extra hypertransport links, or even Cache without any extra chips or protocols.

In old dual or more CPU setups all the CPUs would connect to a "joiner chip" or a northbridge. They would share memory, and fight over the accessing of that memory.

With direct connect either CPU can access their own, or each other's memory without hits in performance.

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' ">http://www.ZapWizard.com
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