Dynamic memory allocation has been a fundamental part of most computer systems since roughly 1960, and memory allocation is widely considered to be either a solved problem or an insoluble one. In this survey, we describe a variety of memory allocator designs and point out issues relevant to their design and evaluation. We then chronologically survey most of the literature on allocators between 1961 and 1995. (Scores of papers are discussed, in varying detail, and over 150 references are given.) We argue that allocator designs have been unduly restricted by an emphasis on mechanism, rather than policy, while the latter is more important; higher-level strategic issues are still more important, but have not been given much attention. Most theoretical analyses and empirical allocator evaluations to date have relied on very strong assumptions of randomness and independence, but real program behavior exhibits important regularities that must be exploited if allocators are to perform well in practice.

Two algorithms are presented for implementing any of a class of buddy systems for dynamic storage allocation. Each buddy system corresponds to a set of recurrence relations which relate the block sizes provided to each other. Analyses of the internal fragmentation of the binary buddysystem, the Fibonai buddy system, and the weighted buddy system are given. Comparative simulation results are also presented for internal, external and total fragmentation.

. We propose several modifications to the binary buddy system for managing dynamic allocation of memory blocks whose sizes are powers of two. The standard buddy system allocates and deallocates blocks in \Theta(lg n) time in the worst case (and on an amortized basis), where n is the size of the memory. We present two schemes that improve the running time to O(1) time, where the time bound for deallocation is amortized. The first scheme uses one word of extra storage compared to the standard buddy system, but may fragment memory more than necessary. The second scheme has essentially the same fragmentation as the standard buddy system, and uses O(2 (1+ p lg n) lg lg n ) bits of auxiliary storage, which is !(lg k n) but o(n " ) for all k 1 and " ? 0. Finally, we present simulation results estimating the effect of the excess fragmentation in the first scheme. 1 Introduction The binary buddy system [13] is a well-known system for maintaining a dynamic collection of me...

We propose several modifications to the binary buddy system for managing dynamic allocation of memory blocks whose sizes are powers of two. The standard buddy system allocates and deallocates blocks in Θ(lg n) time in the worst case (and on an amortized basis), where n is the size of the memory. We present three schemes that improve the running time to O(1) time, where the time bound for deallocation is amortized for the first two schemes. The first scheme uses just one more word of memory than the standard buddy system, but may result in greater fragmentation than necessary. The second and third schemes have essentially the same fragmentation as the standard buddy system, and use O(2 (1+ √ lg n) lg lg n) bits of auxiliary storage, which is ω(lg k n) but o(n ε) for all k ≥ 1 and ε> 0. Finally, we present simulation results estimating the effect of the excess fragmentation in the first scheme.