config ZCACHE tristate "Dynamic compression of swap pages and clean pagecache pages" depends on CRYPTO=y && SWAP=y && CLEANCACHE && FRONTSWAP select CRYPTO_LZO default n help Zcache doubles RAM efficiency while providing a significant performance boosts on many workloads. Zcache uses compression and an in-kernel implementation of transcendent memory to store clean page cache pages and swap in RAM, providing a noticeable reduction in disk I/O. config ZCACHE_DEBUG bool "Enable debug statistics" depends on DEBUG_FS && ZCACHE default n help This is used to provide an debugfs directory with counters of how zcache is doing. You probably want to set this to 'N'. config RAMSTER tristate "Cross-machine RAM capacity sharing, aka peer-to-peer tmem" depends on CONFIGFS_FS=y && SYSFS=y && !HIGHMEM && ZCACHE depends on NET # must ensure struct page is 8-byte aligned select HAVE_ALIGNED_STRUCT_PAGE if !64BIT default n help RAMster allows RAM on other machines in a cluster to be utilized dynamically and symmetrically instead of swapping to a local swap disk, thus improving performance on memory-constrained workloads while minimizing total RAM across the cluster. RAMster, like zcache2, compresses swap pages into local RAM, but then remotifies the compressed pages to another node in the RAMster cluster. config RAMSTER_DEBUG bool "Enable ramster debug statistics" depends on DEBUG_FS && RAMSTER default n help This is used to provide an debugfs directory with counters of how ramster is doing. You probably want to set this to 'N'. # Depends on not-yet-upstreamed mm patches to export end_swap_bio_write and # __add_to_swap_cache, and implement __swap_writepage (which is swap_writepage # without the frontswap call. When these are in-tree, the dependency on # BROKEN can be removed config ZCACHE_WRITEBACK bool "Allow compressed swap pages to be writtenback to swap disk" depends on ZCACHE=y && BROKEN default n help Zcache caches compressed swap pages (and other data) in RAM which often improves performance by avoiding I/O's due to swapping. In some workloads with very long-lived large processes, it can instead reduce performance. Writeback decompresses zcache-compressed pages (in LRU order) when under memory pressure and writes them to the backing swap disk to ameliorate this problem. Policy driving writeback is still under development.