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 generally a good choice for most
  20           environments, but is quite large and complex when compared to the
  21           deadline I/O scheduler, it can also be slower in some cases
  22           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           This is the default I/O scheduler.
  42
  43 choice
  44         prompt "Default I/O scheduler"
  45         default DEFAULT_CFQ
  46         help
  47           Select the I/O scheduler which will be used by default for all
  48           block devices.
  49
  50         config DEFAULT_AS
  51                 bool "Anticipatory" if IOSCHED_AS=y
  52
  53         config DEFAULT_DEADLINE
  54                 bool "Deadline" if IOSCHED_DEADLINE=y
  55
  56         config DEFAULT_CFQ
  57                 bool "CFQ" if IOSCHED_CFQ=y
  58
  59         config DEFAULT_NOOP
  60                 bool "No-op"
  61
  62 endchoice
  63
  64 config DEFAULT_IOSCHED
  65         string
  66         default "anticipatory" if DEFAULT_AS
  67         default "deadline" if DEFAULT_DEADLINE
  68         default "cfq" if DEFAULT_CFQ
  69         default "noop" if DEFAULT_NOOP
  70
  71 endmenu
  72
  73 endif