cuda-gdb 调试问题

加速计算 CUDA
1

使用cuda-gdb调试一段代码，但是在选择进入的block时出现了问题，问题如图：

Breakpoint 1, vector_operation<<<(57,1,1),(512,1,1)>>> (x=0x5455600, 
   y=0x5438e00, z=0x548e600, opera=-1) at spmv_csr.cu:75
75		int threadID=blockDim.x*blockIdx.x+threadIdx.x;
(cuda-gdb) cuda block 50 thread 500
Request cannot be satisfied. CUDA focus unchanged.(cuda-gdb) 
(cuda-gdb)

为什么会Request cannot be satisfied. CUDA focus unchanged？？