Bounce buffer
Beginner
A stop in the processor’s memory where data waits before moving on to where it is really going.
Novice
A staging area in the CPU’s main memory. Data read from a drive is copied there first and then copied again to the accelerator, so it crosses the wires twice.
Expert
Host-memory staging between two DMA transfers. It doubles host-memory traffic, adds latency, burns CPU cycles and makes the root complex (and the inter-socket link) part of the path. Peer-to-peer DMA such as GPUDirect Storage removes it.