[Fwd: Re: [Beowulf] Cell in HPC]

[Richard Walsh]

Greg Lindahl wrote:
> On Tue, May 30, 2006 at 09:12:28AM -0500, Richard Walsh wrote:
>
>   
>>    2.  Three tiered memory system with simple local memory (store,
>>    like old Cray-2) that is user/software managed is preferable to
>>    cache in the above context.  Double buffering and prefetching to
>>    local store reduce memory delays dramatically.
>>     
>
> I wouldn't make this comparison. The Cray 2 local store was much
> easier to use than Cell's software-managed memory. And almost no one
> actually used the Cray 2 local store. Which ought to be a lesson
> learned.
>   
    OK then perhaps, >>more like<< the Cray-2's local memory than like a 
cache, and I used it (but I guess
    that definitely qualifies as "almost no one" ... ;-) ...).  Are you 
wanting to imply that user controlled
    chip-local storage is not that great a design feature for HPC 
generally or more narrowly that the
    CELL's implementation could be better?  
> Another example of a modern machine with software-managed local store
> is QCDOC. Again, this is the easy-to-use kind, very unlike Cell.
>
> -- greg
>
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>   


-- 

Richard B. Walsh

Project Manager
Network Computing Services, Inc.
Army High Performance Computing Research Center (AHPCRC)
rbw at ahpcrc.org  |  612.337.3467

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