Cache-aware block allocation for memory-technology storage targeted file systems

In storage using Non-Volatile Memory (NVM), file placements affect the performance of processor cache. However, the impact of file system policies on processor cache has not been well studied. In particular, sequential block allocation of file systems may incur cache pollution that evicts hot data from cache. To prevent cache pollution, we propose Cache-Aware Block Allocation (CABA) scheme for NVM storage. CABA assigns colors to data blocks in NVM storage such that blocks with the same color compete for cache space. It allocates blocks with specific colors to a file in order to restrict cache space occupied by the file data. A naive color-based block allocation, though, tends to allocate scattered blocks to a file, leading to performance degradation of file systems. To reduce the performance penalty, CABA defines a color group with some consecutive blocks and allocates consecutive blocks in the color group to a file. By so doing, CABA balances cache performance and file system performance. We implement CABA in the Ext4 and NOVA file systems and, through experiments, show performance improvements for memory-intensive programs.