How to pass a array in local address space in Opencl kernel

Question

I want to pass an array to the OpenCL kernel in local address space. But I get CL_invalid_VALUE.

int a[]={1,2,3,4,5};

We don't need to create a buffer to pass data in Local address space. So:

clSetKernelArg(kernel, 21, sizeof(int)*5,a);

In Kernel

__kernel void abc(__local int *a)
{}

If i change the __local to __global, everything works fine. Please tell me how to do this.

I'm not up to speed on opencl, but if the nature and location of the pointed-to memory is indeed relevant, then you haven't provided enough information to determine that. As always, we expect a minimal reproducible example, and your chances of getting a useful answer are greatly improved if you provide one. — John Bollinger
– John Bollinger, Commented Apr 21, 2017 at 13:15

Jovasa · Accepted Answer · 2017-04-25 06:57:37Z

1

You cannot pass anything to local memory from host.

The purpose of spesifying a local pointer in kernel parameters is to spesify the size of the local buffer at the runtime. Then on the clSetKernelArg call the 3rd parameter is the size and the 4th parameter must be NULL.Documentation

Assuming you are using GPU you can either pass it to Constant memory, initialize the local memory in the kernel if it's always the same or just pass it to global memory and then load it in the kernel to local memory preferably using async_work_group_copy.

edited Apr 25, 2017 at 6:57

answered Apr 24, 2017 at 6:31

Jovasa

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2 Comments

anil Over a year ago

But we can pass data to private memory from host. And there is one book called "Opencl Programming guide" by "[Aaftab Munshi, Benedict Gaster, Timothy Mattson" , on page no. - 134 , they show it is possible to pass the elements to local memory from host.

Jovasa Over a year ago

I've edited the answer to hopefully clear any confusion you have.

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