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Why Hawaii/Spectre (R9 290X/A10-7870K R7) slower five ~ ten times than Intel/NVidia on atomic adding operations?

Question asked by mz24cn on Jul 3, 2015
Latest reply on Jul 14, 2015 by mz24cn

The code VS2013 project is attahced.

AMD driver version is 15.2 WHQL (OpenCL 2.0/1.2 1800.3).

 

The results are as below:

//NUM_PARALLEL = 1024;
Platform: AMD Accelerated Parallel Processing
Hawaii
27382 microseconds.
858994483       858996531       5120    7168
Spectre
25421 microseconds.
858994483       858996531       5120    7168
Cypress
24200 microseconds.
858994483       858996531       5120    7168

//NUM_PARALLEL = 1024000000;
Platform: AMD Accelerated Parallel Processing
Hawaii
7784847 microseconds.
1882993459      3930993459      825032704       2873032704
Spectre
64862811 microseconds.
1882993459      3930993459      825032704       2873032704
Cypress
144374737 microseconds.
1882993459      3930993459      825032704       2873032704

 

//NUM_PARALLEL = 1024;
Platform: NVIDIA CUDA
GeForce GTX 850M
2006 microseconds.
858994483       858996531       5120    7168

Platform: Intel(R) OpenCL
Intel(R) HD Graphics 4600
3788 microseconds.
858994483       858996531       5120    7168

//NUM_PARALLEL = 1024000000;
Platform: NVIDIA CUDA
GeForce GTX 850M
568615 microseconds.
1882993459      3930993459      825032704       2873032704

Platform: Intel(R) OpenCL
Intel(R) HD Graphics 4600
12791289 microseconds.
1882993459      3930993459      825032704       2873032704

 

GTX 850M only has 640 shaders while Hawaii has 2816.

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