1config ZCACHE 2 tristate "Dynamic compression of swap pages and clean pagecache pages" 3 depends on CRYPTO=y && SWAP=y && CLEANCACHE && FRONTSWAP 4 select CRYPTO_LZO 5 default n 6 help 7 Zcache doubles RAM efficiency while providing a significant 8 performance boosts on many workloads. Zcache uses 9 compression and an in-kernel implementation of transcendent 10 memory to store clean page cache pages and swap in RAM, 11 providing a noticeable reduction in disk I/O. 12 13config ZCACHE_DEBUG 14 bool "Enable debug statistics" 15 depends on DEBUG_FS && ZCACHE 16 default n 17 help 18 This is used to provide an debugfs directory with counters of 19 how zcache is doing. You probably want to set this to 'N'. 20 21config RAMSTER 22 tristate "Cross-machine RAM capacity sharing, aka peer-to-peer tmem" 23 depends on CONFIGFS_FS=y && SYSFS=y && !HIGHMEM && ZCACHE 24 depends on NET 25 # must ensure struct page is 8-byte aligned 26 select HAVE_ALIGNED_STRUCT_PAGE if !64BIT 27 default n 28 help 29 RAMster allows RAM on other machines in a cluster to be utilized 30 dynamically and symmetrically instead of swapping to a local swap 31 disk, thus improving performance on memory-constrained workloads 32 while minimizing total RAM across the cluster. RAMster, like 33 zcache2, compresses swap pages into local RAM, but then remotifies 34 the compressed pages to another node in the RAMster cluster. 35 36config RAMSTER_DEBUG 37 bool "Enable ramster debug statistics" 38 depends on DEBUG_FS && RAMSTER 39 default n 40 help 41 This is used to provide an debugfs directory with counters of 42 how ramster is doing. You probably want to set this to 'N'. 43 44# Depends on not-yet-upstreamed mm patches to export end_swap_bio_write and 45# __add_to_swap_cache, and implement __swap_writepage (which is swap_writepage 46# without the frontswap call. When these are in-tree, the dependency on 47# BROKEN can be removed 48config ZCACHE_WRITEBACK 49 bool "Allow compressed swap pages to be writtenback to swap disk" 50 depends on ZCACHE=y && BROKEN 51 default n 52 help 53 Zcache caches compressed swap pages (and other data) in RAM which 54 often improves performance by avoiding I/O's due to swapping. 55 In some workloads with very long-lived large processes, it can 56 instead reduce performance. Writeback decompresses zcache-compressed 57 pages (in LRU order) when under memory pressure and writes them to 58 the backing swap disk to ameliorate this problem. Policy driving 59 writeback is still under development. 60