Using OpenCL on Mac OS X - Test for OpenCL Devices

dumpcl.c

// http://stackoverflow.com/a/7898347

#include <stdio.h>
#include <stdlib.h>
#include <OpenCL/opencl.h>

int main(int argc, char* const argv[]) {
    cl_uint num_devices, i;
    clGetDeviceIDs(NULL, CL_DEVICE_TYPE_ALL, 0, NULL, &num_devices);

    cl_device_id* devices = calloc(sizeof(cl_device_id), num_devices);
    clGetDeviceIDs(NULL, CL_DEVICE_TYPE_ALL, num_devices, devices, NULL);

    char buf[128];
    for (i = 0; i < num_devices; i++) {
        clGetDeviceInfo(devices[i], CL_DEVICE_NAME, 128, buf, NULL);
        fprintf(stdout, "Device %s supports ", buf);

        clGetDeviceInfo(devices[i], CL_DEVICE_VERSION, 128, buf, NULL);
        fprintf(stdout, "%s\n", buf);
    }

    free(devices);
}

Makefile

dumpcl:
	clang -framework OpenCL dumpcl.c -o dumpcl && ./dumpcl

try-opencl.py

#!/usr/bin/env python

# http://documen.tician.de/pyopencl/

import pyopencl as cl
import numpy
import numpy.linalg as la

N = 1E8

a = numpy.random.rand(N).astype(numpy.float32)
b = numpy.random.rand(N).astype(numpy.float32)

ctx = cl.create_some_context()
queue = cl.CommandQueue(ctx)

mf = cl.mem_flags
a_buf = cl.Buffer(ctx, mf.READ_ONLY | mf.COPY_HOST_PTR, hostbuf=a)
b_buf = cl.Buffer(ctx, mf.READ_ONLY | mf.COPY_HOST_PTR, hostbuf=b)
dest_buf = cl.Buffer(ctx, mf.WRITE_ONLY, b.nbytes)

prg = cl.Program(ctx, """
    __kernel void sum(__global const float *a,
    __global const float *b, __global float *c)
    {
      int gid = get_global_id(0);
      c[gid] = a[gid] + b[gid];
    }
    """).build()

prg.sum(queue, a.shape, None, a_buf, b_buf, dest_buf)

a_plus_b = numpy.empty_like(a)
cl.enqueue_copy(queue, a_plus_b, dest_buf)

print la.norm(a_plus_b - (a+b))

The code above is no longer meaningfull in 2018.

• calloc return void
• buf is never declared.