  Embedded systems have been used to control physical environments for decades.
Usually, such use cases require low latencies between commands and actions as
well as a high predictability of the expected worst-case delay. To achieve this
on small, low-powered microcontrollers, Real-Time Operating Systems (RTOSs) are
used to manage the different tasks on these machines as deterministically as
possible. However, with the advent of the Internet of Things (IoT) in
industrial applications, the same embedded systems are now equipped with
networking capabilities, possibly endangering critical real-time systems
through an open gate to interrupts. This paper presents our initial study of
the impact network connections can have on real-time embedded systems.
Specifically, we look at three aspects: The impact of network-generated
interrupts, the overhead of the related networking tasks, and the feasibility
of sharing computing resources between networking and real-time tasks. We
conducted experiments on two setups: One treating NICs and drivers as black
boxes and one simulating network interrupts on the machines. The preliminary
results show that a critical task performance loss of up to 6.67% per received
packet per second could be induced where lateness impacts of 1% per packet per
second can be attributed exclusively to ISR-generated delays.
