High Performance, Lock-Free Virtual Storage Manager

摘要

A virtual storage technique is provided to manage a cell pool or a set of cell pools which can be used to satisfy variable-size storage requests. The algorithm uses no locks and relies on an atomic compare-and-swap instruction to serialize updates to the fields that can be simultaneously requested by multiple threads or processes. A free chain is used to manage cells which have already been obtained and freed, while there is an active extent that is used to hand out cells which have not previously been obtained. The algorithm is based on all cell pool extents being the same size, which allows the control information for the extent to be easily located on the extent boundary (e.g. at a 1 MB boundary). Control information for each cell is stored independently of the cell storage in a control array that resides at the head of the extent, along with other control information. This avoids cell overrun from damaging the cell pool control information. The result is a high performance storage manager with good serviceability characteristics.