A computing system dedicates one or more processing units, such as cores, for the purposes of packet processing software, wherein other processing units simultaneously run application software. In some examples, the system uses dynamic load information to dynamically increase and decrease the number of processing units dedicated to packet processing. The system may further include a mechanism for establishing shared-memory regions for interacting with other applications' users. The shared memory mechanisms provide an abstraction of per-application “command” and “completion queues”. The system may poll per-application command queues for detecting the arrival of new requests. The mechanism also provides detection of application termination, as well as an ability for an application to expose portions of its address space for the reception and transmission of data. In some examples, the system further includes a framework for executing software-defined handlers inline with threads that run packet processing and transport software.