Summary: Nonatomic Mutual Exclusion with Local Spinning
Tmax Soft Research Center
272-6 Seohyeon-dong, Seongnam-si
Gyeonggi-do, Korea 463-824
James H. Anderson
Department of Computer Science
University of North Carolina at Chapel Hill
Chapel Hill, NC 27599-3175
April 2003, Revised October 2005
We present an N-process local-spin mutual exclusion algorithm, based on nonatomic reads and writes,
in which each process performs (log N) remote memory references to enter and exit its critical section.
This algorithm is derived from Yang and Anderson's atomic tree-based local-spin algorithm in a way
that preserves its time complexity. No atomic read/write algorithm with better asymptotic worst-case
time complexity (under the remote-memory-references measure) is currently known. This suggests that
atomic memory is not fundamentally required if one is interested in worst-case time complexity.
The same cannot be said if one is interested in fast-path algorithms (in which contention-free time