The Broadcom CPUs in the RPis have unpredictable pauses to let the GPU refresh the RAM (really). That makes them unsuitable for hard real-time applications where you must service an interrupt within a certain time, or emit a signal on a strict deadline, etc.
They're just fine for soft real-time applications where some jitter is acceptable, but what counts as "soft" real-time versus "not-at-all" real-time is the subject of some debate.
The Broadcom CPUs in the RPis have unpredictable pauses to let the GPU refresh the RAM (really). That makes them unsuitable for hard real-time applications where you must service an interrupt within a certain time, or emit a signal on a strict deadline, etc.
They're just fine for soft real-time applications where some jitter is acceptable, but what counts as "soft" real-time versus "not-at-all" real-time is the subject of some debate.