Intel Xeon Phi Coprocessor High Performance Programming

Chapter 7

Offload

Offload refers to writing a program from the point of view of running on processor(s) and offloading work from the host to one or more coprocessors. Execution begins on the host and, based on user-defined code, some sections are offloaded to the coprocessor, if present, or run on the host if not. A key feature of offload is that the resulting binary runs whether or not a coprocessor is present (unless you choose to use #pragma offload target(mic:coproc-num or _Cilk_offload_to) to specify that a coprocessor is required.)

Offloading could simply be thought of an inline code that may be run on a coprocessor, as shown in Figure 7.1.

Figure 7.1 Running Code on a Processor and Offloading to a Coprocessor.

When needed, the compiler ...