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OpenCL on Mali, MapBuffers and lifetime of void* pointers

Hi,

i'm porting an existing OpenCL-using application to ARM/Mali. It already runs, but performance could be better due to unneeded buffer copies.

The ideal OpenCL workflow seems to be:

Init: create a cl_mem object with CL_MEM_ALLOC_HOST_PTR .

Loop:

1. get a void* via clEnqueueMapBuffer

2. Use the void* to fill in data

3. UnMap

4. use the cl_mem object as parameter for a kernel.

but i have a problem in step 1: do i always get the same void* or can this pointer move over time? I basically need this:

Init 1: create a cl_mem object with CL_MEM_ALLOC_HOST_PTR .

Init 2: get a void* via clEnqueueMapBuffer

Init 3: pass the void* into a device driver (very expensive operation)

Loop:

1. wait for the device driver to fill the buffer

2. UnMap

3. use the cl_mem object as parameter for a kernel.

4. clEnqueueMapBuffer, but ignore the new void* because Init 3 is very slow.

Can i really ignore the pointer returned in step 4 and use the first pointer returned in init 3 forever? Is this guaranteed for all Mali-OpenCL implementations?

Thanks

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