Efficient Wait-Free Implementation of Multiword LL/SC Variables

Since the design of lock-free data structures often poses a formidable intellectual challenge, researchers are constantly in search of abstractions and primitives that simplify this design. The multiword LL/SC object is such a primitive: many existing algorithms are based on this primitive, including the nonblocking and wait-free universal constructions (Anderson et. al., 1995), the closed objects construction (Chandra et. al., 1998) and the snap-shot algorithms (Jayanti, 2005, 2002). In this paper, the authors considered the problem of implementing a W-word LL/SC object shared by N processes. The previous best algorithm, due to Anderson and Moir, is time optimal (LL and SC operations run in O(W) time), but has a space complexity of O(N² W). An algorithm that uses novel buffer management ideas to cut down the space complexity by a factor of N to O(NW), while still being time optimal was presented