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POerror CL_OUT_OF_RESOURCES while reading back data in host memory while using atomic function in opencl kernel
 

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  1. POerror CL_OUT_OF_RESOURCES while reading back data in host memory while using atomic function in opencl kernel
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    <p>I am trying to implement atomic functions in my opencl kernel. Multiple threads I am creating are parallely trying to write a single memory location. I want them to perform serial execution on that particular line of code. I have never used an atomic function before. </p> <p>I found similar problems on many blogs and forums,and I am trying one solution.,i.e. use of two different functions 'acquire' and 'release' for locking and unlocking the semaphore. I have included necessary opencl extensions, which are all surely supported by my device (NVIDIA GeForce GTX 630M).</p> <p>My kernel execution configuration:</p> <pre><code>global_item_size = 8; ret = clEnqueueNDRangeKernel(command_queue2, kernel2, 1, NULL, &amp;global_item_size2, &amp;local_item_size2, 0, NULL, NULL); </code></pre> <p>Here is my code: reducer.cl</p> <pre><code>#pragma OPENCL EXTENSION cl_khr_fp64 : enable #pragma OPENCL EXTENSION cl_khr_global_int32_base_atomics : enable #pragma OPENCL EXTENSION cl_khr_local_int32_base_atomics : enable #pragma OPENCL EXTENSION cl_khr_global_int32_extended_atomics : enable #pragma OPENCL EXTENSION cl_khr_local_int32_extended_atomics : enable typedef struct data { double dattr[10]; int d_id; int bestCent; }Data; typedef struct cent { double cattr[5]; int c_id; }Cent; __global void acquire(__global int* mutex) { int occupied; do { occupied = atom_xchg(mutex, 1); } while (occupied&gt;0); } __global void release(__global int* mutex) { atom_xchg(mutex, 0); //the previous value, which is returned, is ignored } __kernel void reducer(__global int *keyMobj, __global int *valueMobj,__global Data *dataMobj,__global Cent *centMobj,__global int *countMobj,__global double *sumMobj, __global int *mutex) { __local double sum[2][2]; __local int cnt[2]; int i = get_global_id(0); int n,j; if(i&lt;2) cnt[i] = countMobj[i]; barrier(CLK_GLOBAL_MEM_FENCE); n = keyMobj[i]; for(j=0; j&lt;2; j++) { barrier(CLK_GLOBAL_MEM_FENCE); acquire(mutex); sum[n][j] += dataMobj[i].dattr[j]; release(mutex); } if(i&lt;2) { for(j=0; j&lt;2; j++) { sum[i][j] = sum[i][j]/countMobj[i]; centMobj[i].cattr[j] = sum[i][j]; } } } </code></pre> <p>Unfortunately the solution doesn't seem like working for me. When I am reading back the centMobj into the host memory, using </p> <pre><code>ret = clEnqueueReadBuffer(command_queue2, centMobj, CL_TRUE, 0, (sizeof(Cent) * 2), centNode, 0, NULL, NULL); ret = clEnqueueReadBuffer(command_queue2, sumMobj, CL_TRUE, 0, (sizeof(double) * 2 * 2), sum, 0, NULL, NULL); </code></pre> <p>it is giving me error with error code = -5 (CL_OUT_OF_RESOURCES) for both centMobj and sumMobj. </p> <p>I am not getting if there is any problem in my atomic function code or problem is in reading back data into the host memory. If I am using the atomic function incorrectly, please make me correct. Thank you in advance.</p>
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