I started with CUDA 2 days ago. I installed the drivers of my Tesla K20m and the CUDA ToolKit. I tested the different examples and all work fine, but now I have a question… I know that this is a stupid question but just I’m starting with parallel computer in my job and I’m not sure.
If I execute the ‘deviceQuery’ I obtain the follow results:
CUDA Device Query (Runtime API) version (CUDART static linking) Detected 1 CUDA Capable device(s) Device 0: "Tesla K20m" CUDA Driver Version / Runtime Version 8.0 / 8.0 CUDA Capability Major/Minor version number: 3.5 Total amount of global memory: 4742 MBytes (4972412928 bytes) (13) Multiprocessors, (192) CUDA Cores/MP: 2496 CUDA Cores GPU Max Clock rate: 706 MHz (0.71 GHz) Memory Clock rate: 2600 Mhz Memory Bus Width: 320-bit L2 Cache Size: 1310720 bytes Maximum Texture Dimension Size (x,y,z) 1D=(65536), 2D=(65536, 65536), 3D=(4096, 4096, 4096) Maximum Layered 1D Texture Size, (num) layers 1D=(16384), 2048 layers Maximum Layered 2D Texture Size, (num) layers 2D=(16384, 16384), 2048 layers Total amount of constant memory: 65536 bytes Total amount of shared memory per block: 49152 bytes Total number of registers available per block: 65536 Warp size: 32 Maximum number of threads per multiprocessor: 2048 Maximum number of threads per block: 1024 Max dimension size of a thread block (x,y,z): (1024, 1024, 64) Max dimension size of a grid size (x,y,z): (2147483647, 65535, 65535) Maximum memory pitch: 2147483647 bytes Texture alignment: 512 bytes Concurrent copy and kernel execution: Yes with 2 copy engine(s) Run time limit on kernels: No Integrated GPU sharing Host Memory: No Support host page-locked memory mapping: Yes Alignment requirement for Surfaces: Yes Device has ECC support: Enabled Device supports Unified Addressing (UVA): Yes Device PCI Domain ID / Bus ID / location ID: 0 / 1 / 0 Compute Mode: < Default (multiple host threads can use ::cudaSetDevice() with device simultaneously) > deviceQuery, CUDA Driver = CUDART, CUDA Driver Version = 8.0, CUDA Runtime Version = 8.0, NumDevs = 1, Device0 = Tesla K20m Result = PASS
My question is about the ‘Maximum number of threads per block’ and ‘Max dimension size of a thread block (x,y,z)’. I understand that 1024 is the maximum number ob threads that I can have in one block but, about the max dimensions size of a thread block is not clear for me… is it means that I can have xyz threads on block? Or is it means that the maximum number of threads in each dimension are x, y, z (in this case 1024,1024,64)?
In my case, if I want a thread block with X=1 and Y=1, the maximum number of threads for Y has to be 64?
Thank you and sorry for the question.
Thanks and best regards.