[Beowulf] New HPCC results and the Myri viewpoint

Vincent Diepeveen diep at xs4all.nl
Wed Jul 20 20:07:08 PDT 2005

>> Tests at all processors at the same time make major sense.
>Yes and no. Most networking people believe the job of a node is to send 
>messages. Actually, it's mainly to compute, and sometimes sends 
>messages. So, would running a pingpong test on multiple processors at 
>the same time sharing a NIC an interesting benchmark ? Not really, it 
>won't happen much on real codes that compute most of the time. I prefer 
>to optimize other things that help the host compute faster.

If most of the time they are 'just computing', then it just doesn't make
sense to have a highend network. A $10 gigabit network will do in that case.

Reality is however different. Reality is that you simply stress the network
until it wastes say 10-20% of your system time until a maximum of 50%.

50% scaling of applications is acceptable, if it exponential speeds up
other calculations.

100% embarrassingly parallel calculations you can so to speak make a
distributed project for with 1 internet server and distribute software.

In short, if you deliver highend nic's, ASSUME they get used.

At least *i* understand that principle.

Weirdly enough the manufacturer of a product assumes his stuff isn't going
to get used.

Why make it then for your users?

You try to sell a product without your users using it?


>> Any denial in advance that it will be the same speed is just ballony.
>And I thought I was the bulliest on this list...
>I just give my opinion and at least my opinion is backed up by 
>first-hand experience. I don't know how to play chess, but I know my stuff.
>Patrick Geoffray
>Myricom, Inc.

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