CUDA

Info

1. How is 2D Shared Memory arranged in CUDA
   • http://stackoverflow.com/questions/7903566/how-is-2d-shared-memory-arranged-in-cuda

Written Bugs

1. wait forever due to s_changed if-else case

   __shared__ int s_data[BLOCKWIDTH][BLOCKWIDTH];
   if(val == 0) return;  // make sure maybe its connected
   
   int label = Block1DAddress;
   
   while(1)
   {
       // Pass 1 of the CCL algorithm
       s_labels[Block1DAddress] = label;
       if(Block1DAddress == 0) s_changed[0] = 0;
       __syncthreads();
       ...
       if(s_changed[0] == 0) break;
   }
   

   上述程序，我让val == 0的线程全部return了，但是下面while里面写了如果Block1DAddress==0的话才break，这样导致了如果一个block里面的第0个thread的值是0，s_changed就永远无法初始化为0

Solutions

1. __syncthreads的用法，防止wait forever的情况
   • http://www.cnblogs.com/dwdxdy/p/3215136.html