Summary: Using Lock­Free Objects in Hard Real­Time Applications \Lambda
James H. Anderson and Srikanth Ramamurthy
Department of Computer Science, The University of North Carolina at Chapel Hill
Lock­based approaches to object sharing are the ac­
cepted means of interprocess communication in real­
time systems. The main problem that arises under such
approaches is that of priority inversion, i.e., the situ­
ation in which a given task 1 waits on another task of
lower priority to exit a critical section. Mechanisms
such as the priority ceiling protocol (PCP) [3] are used to
solve this problem. The PCP requires the operating sys­
tem to identify those tasks that may lock a semaphore,
which results in additional complexity in operating sys­
tem services. This information is used to ensure that the
priority of a task holding a semaphore is at least that
of the highest­priority task that locks that semaphore.
In [1], we propose using lock­free objects as an alter­
native for object sharing in real­time systems. Lock­free
objects are usually implemented using ``retry loops''. For
example, in the universal, lock­free implementation pre­

Source: Anderson, James - Department of Computer Science, University of North Carolina at Chapel Hill

Collections: Computer Technologies and Information Sciences