[SYCL][Graph] Extend Buffer Lifetime

[EwanC]

Ben's WIP work extending the lifetime of buffers used in a graph with buffer::get_access(CGH) when SYCL_GRAPH_EXTEND_BUFFER_LIFETIMES is set.

TODO:

• Needs tested with a oneDNN example that uses internal scratchpad buffers
• The assume_buffer_outlives_graph constraint could be relaxed when env var is set

[guoyejun]

hi, could you share where is the change of the sycl graph spec?

[EwanC]

hi, could you share where is the change of the sycl graph spec?

Hello, this isn't in the spec yet. This is a proof-of-concept implementation we are wanting to try with some workloads that use buffers internally before advertising in the spec.

It may not be satisfactory by itself as it is only a partial solution - as it only extends the lifetime of buffers when the accessor is created inside the command-group with buffer.get_access(). A full solution to extending buffer lifetimes will also require extending the lifetimes of buffers when the accessor is created outside of the command-group, and then passed in and used with handler::require().