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Simple Reductions algorithm clarification

Question asked by vaspa on Mar 27, 2012
Latest reply on Mar 27, 2012 by notzed

Hello, guys.

 

I have been studying some parallel algorithms from the database here in the past couple of days.

In one specific - The two-stage parallel reduction - there is something that is just slipping away from me.

http://developer.amd.com/documentation/articles/Pages/OpenCL-Optimization-Case-Study-Simple-Reductions_6.aspx

 

A preferred number of work-groups is given, but nothing is said about the number of work-items in a work-group. How many is the optimal or what is the logic?

 

So just to be clear with my understanding of the execution model concerning this I have a couple of blitz questions:

1) A Processing Element actually is the unit that executes instructions?

2) A Compute unit is an artificial abstraction of the hardware?

3) There cannot be more work-items in a work-group than are the number of Processing Elements on the device?

 

A greatly appreciate any help in advance.

 

Best regards,

Dilyan Dokov.

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