[Beowulf] Re: GPU Beowulf Clusters

richard.walsh at comcast.net richard.walsh at comcast.net
Mon Feb 1 12:54:45 PST 2010

Jon Forrest <jlforrest at berkeley.edu> wrote: 

>On 2/1/2010 7:24 AM, richard.walsh at comcast.net wrote: 
>> Coming in on this late, but to reduce this work load there is PGI's version 
>> 10.0 compiler suite which supports accelerator compiler directives. This 
>> will reduce the coding effort, but probably suffer from the classical 
>> "if it is 
>> easy, it won't perform as well" trade-off. My experience is limited, but 
>> a nice intro can be found at: 
>I'm not sure how much traction such a thing will get. 
>Let's say you have a big Fortran program that you want 
>to port to CUDA. Let's assume you already know where the 
>program spends its time, so you know which routines 
>are good candidates for running on the GPU. 
>Rather than rewriting the whole program in C[++], 
>wouldn't it be easiest to leave all the non-CUDA 
>parts of the program in Fortran, and then to call 
>CUDA routines written in C[++]. Since the CUDA 
>routines will have to be rewritten anyway, why 
>write them in a language which would require 
>purchasing yet another compiler? 

Mmm ... not sure I understand the response, but perhaps this response 
was to a different message ... ?? In any case, the PGI software supports 
accelerator directives for both C and Fortran, so for those languages I do 
not see a need to rewrite whole applications. The question presented is 
the same as always, what does the performance-programming effort function 
look like and how well does your code perform with directives to start 
with. The PGI models is also hardware generic and the code runs on 
the CPU in parallel when there is no GPU around I believe. What will 
gate interest is how well PGI compiler group does at delivering performance 
and how important portability is to the person developing the code. 

HMPP make offers a similar proposition ... 


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