1 research outputs found
An Adaptive Approach to Recoverable Mutual Exlcusion
Mutual exclusion (ME) is one of the most commonly used techniques to handle
conflicts in concurrent systems. Traditionally, mutual exclusion algorithms
have been designed under the assumption that a process does not fail while
acquiring/releasing a lock or while executing its critical section. However,
failures do occur in real life, potentially leaving the lock in an inconsistent
state. This gives rise to the problem of \emph{recoverable mutual exclusion
(RME)} that involves designing a mutual exclusion algorithm that can tolerate
failures, while maintaining safety and liveness properties.
One of the important measures of performance of any ME algorithm, including
an RME algorithm, is the number of \emph{remote memory references (RMRs)} made
by a process (for acquiring and releasing a lock as well as recovering the lock
structure after a failure). The best known RME algorithm solves the problem for
processes in sub-logarithmic number of RMRs, given by
, irrespective of the number of
failures in the system.
In this work, we present a new algorithm for solving the RME problem whose
RMR complexity gradually \emph{adapts} to the number of failures that have
occurred in the system "recently". In the absence of failures, our algorithm
generates only RMRs. Furthermore, its RMR complexity is given
by where is
the total number of failures in the "recent" past. In addition to read and
write instructions, our algorithm uses compare-and-swap (\CAS{}) and
fetch-and-store (\FAS{}) hardware instructions, both of which are commonly
available in most modern processors