The SCHED_DEADLINE scheduler is a more advanced scheduler but is still very
simple to use with Cactus-RT. In fact, it is almost identical to the looping
thread based on SCHED_FIFO as shown in simple_example.
See https://www.kernel.org/doc/html/latest/scheduler/sched-deadline.html for more details on how to configure this scheduler for your application.
CPU affinity currently cannot be used with SCHED_DEADLINE for unknown reasons.
Setting CPU affinity will cause sched_setattrs to fail with EPERM, which
results in an Operation not permitted error on startup of this example.
Also see: https://lwn.net/Articles/745626/