There is threadgroup shared memory (also known as local data share), provided at 64kB per block of execution units (this block is called a "subslice" in Intel,

There is threadgroup shared memory (also known as local data share), provided at 64kB per block of execution units (this block is called a "subslice" in Intel, a "streaming multiprocessor" in Nvidia, and "compute unit" in AMD). Though the exact ratios vary widely, this memory has about an order of magnitude higher bandwidth and lower latency than access to global memory, and when used skillfully really can enable systolic-like architectures.