Subject: Re: Response to Grassl - what we are benchmarking

From: Vladimir Getov <[email-masked]>
Date: Wed, 5 Jan 94 18:41:31 GMT

What we are benchmarking
------------------------
> 
> >Distributed memory seems to be what we are benchmarking.  The key
> >differentiator of MPP systems is their non-local memory access
> >patterns.
> 
>     The PARKBENCHmarks are actually either message-passing programs
>     and/or HPF programs. They therefore can be used on and can test 
>     any computer whose software supports these models of programming.
>     This statement is quite independent of the nature of the hardware
>     which may or may not, at the hardware level, send messages or
>     have data parallel (i.e. SIMD as opposed to MIMD) control.
>     However, we have no benchmarks which use the shared memory or DMA 
>     model of parallel programming. Come to think of it, HPF is a special
>     rather restricted case of DMA (there are certainly no messages).  
>     My view is that our benchmarks test the efficiency of certain
>     prgramming models on a particular computer, and it should be clearly
>     stated that this does not imply anything about the underlying
>     hardware. Other views please.
>
I firmly support this position - what we see from our `high level language'
point of view is the programming model. Currently, three programming
models seem to be of major interest:

(1) Conventional (sequential) - based usually on Fortran 77, this model
    assumes the implementation of automatic vectorisers and/or
    parallelisers during the compilation on a parallel computer;
(2) Message-passing - it exist in two versions - Master/Slave and Hostless;
(3) Data parallel model - HPF/Fortran 90.

Ideally, the PARKBENCHmarks should have three versions for the above
programming models.
> 
> >I recommend using the label "distributed memory computers".
> 
>     I have noted this preference, but still have an open mind.
>
Why don't using the label from the title of our report - "parallel
computers". Virtually all possible kinds of parallel computers conform
to this label - distributed memory parallel computers, shared memory
parallel computers, message-passing parallel computers, etc.; even
massively parallel computers sounds not too bad!
> 
> Thanks for your contribution
> 
>                     Roger Hockney
>
Vladimir Getov