Subject: Re: Response to Grassl - node definition

From: Vladimir Getov <[email-masked]>
Date: Wed, 5 Jan 94 15:01:24 GMT

Node definition
---------------
> 
> >Node and processors are often used incorrectly in an interchangable
> >fashion.  A node is a network location and a processor is a CPU of some
> >sort.  On a CRAY T3D there are two CPUs, we call them Processor
> >Elements (PEs), per node.  The Intel Paragon has two i860 CPUs at each
> >node site, one for computation and one for communication.
> 
I support this point, but think it still needs deeper clarification. 
For instance, there are network locations in shared memory computers but
we don't call them nodes. A node, therefore, is a network location
specific to distributed memory computers, having its own chunk of local
memory, a set of processing (computation) and communication elements,
optional I/O facilities, etc. For example, one node in CM-2 consists of
some local memory, 32 bit-slice processing elements, communication
elements, a floating point accelerator, etc.
>
>     A very good point. Thanks for the clarification. I will use the
>     distinction which is an important one to make. It will probably 
>     mean that most references to node (if they really mean processor 
>     at a node) will be replaced by processor.
> 
There are also references to `processor' which really mean `node' in our
report. In chapter 2, for example, we introduce a number of 
2-dimensional performance metrics, one of the dimensions being the
number of processors, p. In reality, however, when benchmarking
distributed memory parallel computers, we use the number of nodes rather
than the number of processors. I propose that the same variable (p)
should be kept, clarifying that it means the number of processors for 
shared memory parallel computers and the number of nodes for distributed
memory parallel computers.

... - Other stuff deleted - vsg

>                     Roger Hockney
Vladimir Getov