block/Kconfig.iosched

   1
   2 menu "IO Schedulers"
   3
   4 config IOSCHED_NOOP
   5         bool
   6         default y
   7         ---help---
   8           The no-op I/O scheduler is a minimal scheduler that does basic merging
   9           and sorting. Its main uses include non-disk based block devices like
  10           memory devices, and specialised software or hardware environments
  11           that do their own scheduling and require only minimal assistance from
  12           the kernel.
  13
  14 config IOSCHED_AS
  15         tristate "Anticipatory I/O scheduler"
  16         default y
  17         ---help---
  18           The anticipatory I/O scheduler is the default disk scheduler. It is
  19           generally a good choice for most environments, but is quite large and
  20           complex when compared to the deadline I/O scheduler, it can also be
  21           slower in some cases especially some database loads.
  22
  23 config IOSCHED_DEADLINE
  24         tristate "Deadline I/O scheduler"
  25         default y
  26         ---help---
  27           The deadline I/O scheduler is simple and compact, and is often as
  28           good as the anticipatory I/O scheduler, and in some database
  29           workloads, better. In the case of a single process performing I/O to
  30           a disk at any one time, its behaviour is almost identical to the
  31           anticipatory I/O scheduler and so is a good choice.
  32
  33 config IOSCHED_CFQ
  34         tristate "CFQ I/O scheduler"
  35         default y
  36         ---help---
  37           The CFQ I/O scheduler tries to distribute bandwidth equally
  38           among all processes in the system. It should provide a fair
  39           working environment, suitable for desktop systems.
  40
  41 choice
  42         prompt "Default I/O scheduler"
  43         default DEFAULT_AS
  44         help
  45           Select the I/O scheduler which will be used by default for all
  46           block devices.
  47
  48         config DEFAULT_AS
  49                 bool "Anticipatory" if IOSCHED_AS
  50
  51         config DEFAULT_DEADLINE
  52                 bool "Deadline" if IOSCHED_DEADLINE
  53
  54         config DEFAULT_CFQ
  55                 bool "CFQ" if IOSCHED_CFQ
  56
  57         config DEFAULT_NOOP
  58                 bool "No-op"
  59
  60 endchoice
  61
  62 config DEFAULT_IOSCHED
  63         string
  64         default "anticipatory" if DEFAULT_AS
  65         default "deadline" if DEFAULT_DEADLINE
  66         default "cfq" if DEFAULT_CFQ
  67         default "noop" if DEFAULT_NOOP
  68
  69 endmenu