Notes for backend implementations

The KernelInterface sibling package defines the core interface a backend must implement. A backend must implement a backend type that subtypes KernelInterface.GPU, or KernelInterface.Backend for non-gpu backends. This documentation contains the host and devices side functions that backends can define, as well as whether they are mandatory or not.

Semantics of KernelAbstractions.synchronize

KernelAbstractions.synchronize is required to be cooperative, with that we mean it can not block inside an external library, but instead must implement a cooperative wait that will yield the current task and return the scheduling slice to the Julia runtime.

This is of particular import to allow for overlapping of communication and computation with MPI.