Posted by devmonkey on Jul 03, 2015; 8:27pm
URL: https://forum.jogamp.org/Dual-GPU-7990-card-not-using-both-GPUs-concurrently-tp4034813p4034820.html

Hi Wade,

You nailed it. I updated JOCLMultiDeviceSample.java to call clFlush after each enqueue and now it does indeed run on both gpus concurrently. Do you think this is just a problem with my particular card or a general problem with the sample code?

The change I made to the kernel in order to make it run long enough is:

 private static String programSource =
        "__kernel void sampleKernel(__global const float *input,"+
        "                           __global float *output, " +
        "                           int size)"+
        "{"+
        "    int gid = get_global_id(0);"+
        "    output[gid] = 0;" +
        "    for (int j=0;j<100000;j++) {" +
        "    for (int i=0; i<size; i++) " +
        "        output[gid] += input[i];" +
        "}}";


Cheers, Joe