Streaming multiprocessor (SM) / compute unit (CU)
Beginner
One of the many cores on a GPU. Each one has its own math units and its own small, fast memory.
Novice
The GPU’s basic core. NVIDIA calls it a streaming multiprocessor, AMD a compute unit. It holds a register file, a small cache and shared memory, warp schedulers, and math and matrix units. A big GPU has around a hundred or more.
Expert
A multithreaded core partitioned into (typically four) scheduler quadrants or SIMDs. All threads of a thread block run on one SM, and the SM’s registers, shared memory and warp slots set how many blocks fit.
Explained in SIMT and GPUs (Architectures).
See also: Warp scheduler, Register file, Shared memory (LDS).