The prologue and epilogue blocks are tricks that

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Unformatted text preview: ated block obtained from a previous allocate request. Thus the allocator cannot make any assumptions about the ordering of allocate and free requests. For example, the allocator cannot assume that all allocate requests are accompanied by a matching free, or that matching allocate and free requests are nested. Making immediate responses to requests. The allocator must respond immediately to allocate requests. Thus the allocator is not allowed to reorder or buffer requests in order to improve performance. Using only the heap. In order for the allocator to be scalable, any non-scalar data structures used by the allocator must be stored in the heap itself. Aligning blocks (alignment requirement). The allocator must align blocks in such a way that they can hold any type of data object. On most systems, this means that the block returned by the allocator is aligned on an eight-byte (double-word) boundary. Not modifying allocated blocks. Allocators can only manipulate or change free blocks. In particular, they are not allowed to modify or move blocks once they are allocated. Thus, techniqu...
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