drivers/staging/zcache/Kconfig

   1 config ZCACHE
   2         bool "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
  13 config 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
  21 config RAMSTER
  22         bool "Cross-machine RAM capacity sharing, aka peer-to-peer tmem"
  23         depends on CONFIGFS_FS=y && SYSFS=y && !HIGHMEM && ZCACHE=y
  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
  36 # Depends on not-yet-upstreamed mm patches to export end_swap_bio_write and
  37 # __add_to_swap_cache, and implement __swap_writepage (which is swap_writepage
  38 # without the frontswap call. When these are in-tree, the dependency on
  39 # BROKEN can be removed
  40 config ZCACHE_WRITEBACK
  41         bool "Allow compressed swap pages to be writtenback to swap disk"
  42         depends on ZCACHE=y && BROKEN
  43         default n
  44         help
  45           Zcache caches compressed swap pages (and other data) in RAM which
  46           often improves performance by avoiding I/O's due to swapping.
  47           In some workloads with very long-lived large processes, it can
  48           instead reduce performance.  Writeback decompresses zcache-compressed
  49           pages (in LRU order) when under memory pressure and writes them to
  50           the backing swap disk to ameliorate this problem.  Policy driving
  51           writeback is still under development.