Assignment 6 Cuda Threads

[Andy Liu]

How do we know how many CUDA threads to launch? wouldn't we need to know how many cuda cores are available for the csil computer?

Thank you

[Arrvindh Shriraman]

You distribute based on problem size (not CUDA cores).

Thread blocks is 1D or 2D (limited by the amount of shared memory you want to cumulatively use across all threads in block). Typically thread blocks would be 128 or 256 threads. 

Grid 1D, 2D or 3D

The CSIL machines have a compute device # 61. 

https://en.wikipedia.org/wiki/Thread_block_(CUDA_programming) . This is a pretty good description.

See here how we estimate block size based on matrix size

https://github.com/CMPT-431-SFU/CUDA-Demos/blob/eb108a906d3d226afbd53e0489806fceacc481fe/src/matrixMul/matrixMul.cu#L316