Absolutely positively on time: what would it take? [embedded computing systems
Edward A. Lee · Computer · 2005
Despite considerable progress in software and hardware techniques, many recent computing advances do more harm than good when embedded computing systems absolutely must meet tight timing constraints. For example, while synchronous digital logic delivers precise timing determinacy, advances in computer architecture and software have made it difficult or impossible to estimate or predict software's execution time. Moreover, networking techniques introduce variability and stochastic behavior, while operating systems rely on best-effort techniques. Worse, programming language semantics do not handle time well, so developers can only specify timing requirements indirectly. Thus, achieving precise timeliness in a networked embedded system - an absolutely essential goal - requires sweeping changes. For embedded computing to realize its full potential, we must reinvent computer science. Resource limitations have influenced embedded software's evolution. Embedded software differs from other software in more fundamental ways.