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vignyan
Journeyman III

FFT sample run on GPU

Causes display freeze on Ubuntu

Hi, 

I  have Ubuntu 9.10 32 bit with SDK2.01 installed on my laptop with Intel core2 duo P7350 and ATI HD4650.

When i run the code on cpu, it does run properly. When i run on GPU, the display freezes. I can still hear my music playing in the background, but cant see anything moving on the screen (mouse, keyboard, change to console mode... nothing)...

Any ideas?

Thanks,

Vignyan

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5 Replies
omkaranathan
Journeyman III

FFT sample run on GPU

The issue is with FFT sample only? or other samples too?

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vignyan
Journeyman III

FFT sample run on GPU

Matrix Multiplication works just fine.

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n0thing
Journeyman III

FFT sample run on GPU

The FFT kernel was designed to run specifically on work-group size 64 but seems like your video-card doesn't support that size on that kernel.

To query the maximum size supported by your card for a particular kernel you can use the function clGetKernelWorkGroupInfo with input flag  CL_KERNEL_WORK_GROUP_SIZE.

The sample should just exit if this size is less than 64.

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vignyan
Journeyman III

FFT sample run on GPU

yeah, that's what i would have expected. Just fail, like other programs when i try to use group sizes of 256(specifying block size of 64) ... BTW, my card's kernel work group size is 128. Why does the graphics card stop display activity in anycase?

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omkaranathan
Journeyman III

FFT sample run on GPU

vignyan,

Maximum groupsize in 7xx cards is 64 currently, if you are using barrier.

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