[Beowulf] Re: newbies' dilemma / firewire? (Hahn) (Will) (Geoffray) (Lindahl)

Ed Karns edkarns at firewirestuff.com
Fri Mar 10 09:36:37 PST 2006

On Mar 9, 2006, at 7:32 PM, beowulf-request at beowulf.org wrote:

> Michael Will wrote:
>> Infiniband with DDR is already at 20Gbps over CX4 copper
> Over 3 meters cables thick as firehose. 5 meters if you like to  
> play with fire.
> There is a time when fiber is the right thing to do. However, WDM  
> solutions are still expensive, it's much cheaper to use several fibers
> per cable. You can run 12.5 Gbps Ethernet over 200 meters [today] ...
> Patrick

... what he said ...

> Processor efficiency FireWire has a 32-bit "risc" type  
> microprocessor, is peer to peer in hardware / firmware and has  
> other lean architecture features.

Uh, is having a 32-bit CPU in your NIC supposed to make it faster or  
slower? In the InfiniBand space, there's a proof that having that
extra cpu makes small packets slower. With FireWire's slower link  
[microprocessor] speed ...


The old "bus arbitrator" question = depends on the task at hand:  
small files / small packets = greater overhead = extra data in the  
packet frame v. data transmitted ... large files / larger packets =  
lesser overhead = massive data delivered v. size of packet.

This may be at the heart of my question: which hardware protocol is  
optimum (for a "glass bus" ?) interconnecting multiple processors in  
a local network? If anyone should know this answer, the bleeding edge  
builders of clusters should = the members of this group.

If everything else is equal:
microprocessor speed / bus speed = same, same
parallel "bit number" = 32 bit? 64 bit?
address space = 32 nodes? 64 nodes? 256 nodes? more?
line length = greatest distance between node clusters = 10 feet? 100  
feet? 10,000 feet?

... which protocol would perform the best?

If anyone should know this answer or be able to make a very well  
educated guess, the bleeding edge builders of Beowulf clusters should  
= the members of this group.

Ed Karns

A meat space reference: FireWire 800 = double duplex, metal (8 wire)  
or glass (2 fiber)  = 32 bit microprocessor (speed dependent on host  
bus)  = 800 megabits per second = streaming, large data frame / file  
transfer rate = 80 MegaBytes per second ~~= 8 DVD resolution videos,  

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