View Full Version : functions called in a kernel

06-16-2010, 04:13 AM

this is my problem, I have 3 functions in my .cl file and I called them in a kernel. it'a an image processing functions, so I do 3 transformations on the image, now I'm working in the global memory, but I want to work in the local.

what I want to do is to transfer work-groups to local memory, do the 3 operations then write the result back to global, but since each transformation is a separate function, is this possible?

I can detail more if needed.

06-21-2010, 02:44 AM
You need to change the signature of your functions to pass pointers to local mem:

void Fun(__local float2* t1, __local float* t2, float eta, unsigned int v)

If I understand you correctly you should:
1. Download work-group data into local memory from global memory (preferably in coalesced fashion - I'm assuming you're targeting gpu architecture)
2. Process the data in local memory - by invoking your functions with appropriate pointers
3. When done write results to global memory

I don't quite get "(...) transfer work-groups to local memory". Work-group is execution, memory is memory. Work-groups consist of work-items executing in parallel. Every work-item from a work-group executes a kernel. Local memory is shared by all work-items in a work-group, while global memory is accessible to all work-items from all work-groups.
In general you should batch and minimize your transfers from/to global memory and work as much as possible on fast local memory.