In the CAST-32A position paper published by the FAA, an interference channel is defined as "a platform property that may cause interference between independent applications". This definition can be applied to a range of ‘platform properties’, including thermal factors etc.
Of these interference channels, interference caused by the sharing of certain resources in multicore systems is one of the most significant in terms of execution times. Interference based on shared resources may occur in multicore systems when multiple cores simultaneously compete for use of shared resources such as buses, caches and main memory.
Rapita’s Multicore Timing Solution analyzes the effects of this type of interference channel.
A very simple example of a shared resource interference channel is as follows:
In this simplified example, tasks running independently on the two cores may need to access main memory simultaneously via the memory controller. These accesses can interfere with each other, potentially degrading system performance.