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Add a kconfig submenu to select the default I/O scheduler, in case anticipatory is not compiled in or another default is preferred. Also, since no-op is always available, we should use it whenever the selected default is not. Signed-off-by: Nate Diller <nate@namesys.com> Acked-by: Jens Axboe <axboe@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
70 lines
1.9 KiB
Plaintext
70 lines
1.9 KiB
Plaintext
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menu "IO Schedulers"
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config IOSCHED_NOOP
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bool
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default y
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---help---
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The no-op I/O scheduler is a minimal scheduler that does basic merging
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and sorting. Its main uses include non-disk based block devices like
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memory devices, and specialised software or hardware environments
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that do their own scheduling and require only minimal assistance from
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the kernel.
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config IOSCHED_AS
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tristate "Anticipatory I/O scheduler"
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default y
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---help---
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The anticipatory I/O scheduler is the default disk scheduler. It is
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generally a good choice for most environments, but is quite large and
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complex when compared to the deadline I/O scheduler, it can also be
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slower in some cases especially some database loads.
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config IOSCHED_DEADLINE
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tristate "Deadline I/O scheduler"
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default y
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---help---
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The deadline I/O scheduler is simple and compact, and is often as
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good as the anticipatory I/O scheduler, and in some database
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workloads, better. In the case of a single process performing I/O to
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a disk at any one time, its behaviour is almost identical to the
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anticipatory I/O scheduler and so is a good choice.
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config IOSCHED_CFQ
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tristate "CFQ I/O scheduler"
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default y
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---help---
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The CFQ I/O scheduler tries to distribute bandwidth equally
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among all processes in the system. It should provide a fair
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working environment, suitable for desktop systems.
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choice
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prompt "Default I/O scheduler"
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default DEFAULT_AS
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help
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Select the I/O scheduler which will be used by default for all
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block devices.
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config DEFAULT_AS
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bool "Anticipatory" if IOSCHED_AS
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config DEFAULT_DEADLINE
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bool "Deadline" if IOSCHED_DEADLINE
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config DEFAULT_CFQ
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bool "CFQ" if IOSCHED_CFQ
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config DEFAULT_NOOP
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bool "No-op"
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endchoice
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config DEFAULT_IOSCHED
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string
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default "anticipatory" if DEFAULT_AS
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default "deadline" if DEFAULT_DEADLINE
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default "cfq" if DEFAULT_CFQ
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default "noop" if DEFAULT_NOOP
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endmenu
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