Grand Central Dispatch (GCD or libdispatch) provides comprehensive support for
concurrent code execution on multicore hardware.

libdispatch is currently available on all Darwin platforms. This project aims
to make a modern version of libdispatch available on all other Swift platforms.
To do this, we will implement as much of the portable subset of the API as
possible, using the existing open source C implementation.

libdispatch on Darwin is a combination of logic in the xnu kernel alongside the
user-space Library. The kernel has the most information available to balance
workload across the entire system. As a first step, however, we believe it is
useful to bring up the basic functionality of the library using user-space
pthread primitives on Linux. Eventually, a Linux kernel module could be
developed to support more informed thread scheduling.