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Multiple same kernel call behavior

Altera_Forum
Honored Contributor II
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What is the expected behavior when the same kernel is called multiple times on the FPGA, where the input is the output buffer as well. 

 

 

Suppose I have a vector increment kernel that I call K consecutive times. Moreover, the kernel call launches only a single work-group of some dimension N. What is the behavior of the FPGA board? 

 

 

A - Does it run each kernel fully pipelined, i.e. the will the first work-item of the (i+1)-th call be pipelined with the last work-item of the i-th call? 

 

B - Will the i-th call completely finish before the (i+1)-th call start? 

 

 

This case is trivial, I can always add K to the vector instead of calling K times the increment kernel. But suppose the FFT case, where I'm confronted with unrolling all the stages in the same kernel, thus calling several times barrier(CLK_LOCAL_MEM_FENCE) which reduces the kernel performance, or calling several radix-n kernels. If the hypothesis B holds, then the former strategy might be better, but if A holds then the latter should deliver a greater performance. 

 

Which one is expectable?
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Altera_Forum
Honored Contributor II
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Scenerio B is expected.

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