block/Kconfig.iosched

   1 if BLOCK
   2
   3 menu "IO Schedulers"
   4
   5 config IOSCHED_NOOP
   6         bool
   7         default y
   8         ---help---
   9           The no-op I/O scheduler is a minimal scheduler that does basic merging
  10           and sorting. Its main uses include non-disk based block devices like
  11           memory devices, and specialised software or hardware environments
  12           that do their own scheduling and require only minimal assistance from
  13           the kernel.
  14
  15 config IOSCHED_AS
  16         tristate "Anticipatory I/O scheduler"
  17         default y
  18         ---help---
  19           The anticipatory I/O scheduler is the default disk scheduler. It is
  20           generally a good choice for most environments, but is quite large and
  21           complex when compared to the deadline I/O scheduler, it can also be
  22           slower in some cases especially some database loads.
  23
  24 config IOSCHED_DEADLINE
  25         tristate "Deadline I/O scheduler"
  26         default y
  27         ---help---
  28           The deadline I/O scheduler is simple and compact, and is often as
  29           good as the anticipatory I/O scheduler, and in some database
  30           workloads, better. In the case of a single process performing I/O to
  31           a disk at any one time, its behaviour is almost identical to the
  32           anticipatory I/O scheduler and so is a good choice.
  33
  34 config IOSCHED_CFQ
  35         tristate "CFQ I/O scheduler"
  36         default y
  37         ---help---
  38           The CFQ I/O scheduler tries to distribute bandwidth equally
  39           among all processes in the system. It should provide a fair
  40           working environment, suitable for desktop systems.
  41
  42 choice
  43         prompt "Default I/O scheduler"
  44         default DEFAULT_CFQ
  45         help
  46           Select the I/O scheduler which will be used by default for all
  47           block devices.
  48
  49         config DEFAULT_AS
  50                 bool "Anticipatory" if IOSCHED_AS=y
  51
  52         config DEFAULT_DEADLINE
  53                 bool "Deadline" if IOSCHED_DEADLINE=y
  54
  55         config DEFAULT_CFQ
  56                 bool "CFQ" if IOSCHED_CFQ=y
  57
  58         config DEFAULT_NOOP
  59                 bool "No-op"
  60
  61 endchoice
  62
  63 config DEFAULT_IOSCHED
  64         string
  65         default "anticipatory" if DEFAULT_AS
  66         default "deadline" if DEFAULT_DEADLINE
  67         default "cfq" if DEFAULT_CFQ
  68         default "noop" if DEFAULT_NOOP
  69
  70 endmenu
  71
  72 endif