Test kernel that uses IO channel reads from Global Memory more than expected

It is an OpenCL kernel for Intel FPGA. Below is an example of the test kernel. This is just a loopback test kernel. Host writes data to GM of FPGA1. ioch_out_kernel reads the data from GM, then writes the same data to ioch_out channel ioch_in_kernel reads the data from ioch_in channel, then writes the same data to GM Host then reads the data from GM of FPGA2. Host should read the same data it writes to GM of FPGA1. For big data transfer (size>=2048, which means 64KB), the test kernel below works ok. If size =< 1024 (32KB or less), the test kernel below doesn't work ok.