 
Summary: Adaptive Mutual Exclusion with Local Spinning ?
James H. Anderson and YongJik Kim
Department of Computer Science, University of North Carolina at Chapel Hill
Abstract. We present the rst adaptive algorithm for Nprocess mutual
exclusion under read/write atomicity in which all busy waiting is by local
spinning. In our algorithm, each process p performs O(min(k; log N))
remote memory references to enter and exit its critical section, where k is
the maximum \point contention" experienced by p. The space complexity
of our algorithm is (N ), which is clearly optimal.
1 Introduction
In this paper, we consider adaptive solutions to the mutual exclusion problem
[7] under read/write atomicity. A mutual exclusion algorithm is adaptive if its
time complexity is a function of the number of contending processes [6, 11, 13].
Two notions of contention have been considered in the literature: \interval con
tention" and \point contention" [1]. These two notions are dened with respect
to a history H . The interval contention over H is the number of processes that
are active in H , i.e., that execute outside of their noncritical sections in H . The
point contention over H is the maximum number of processes that are active at
the same state in H . Note that point contention is always at most interval con
tention. In this paper, we consider only point contention. Throughout the paper,
