LBD
bool "Support for Large Block Devices"
depends on X86 || (MIPS && 32BIT) || PPC32 || ARCH_S390_31 || SUPERH || UML
help
Say Y here if you want to attach large (bigger than 2TB) discs to
your machine, or if you want to have a raid or loopback device
bigger than 2TB. Otherwise say N.
I/O Schedulers[]
menu "IO Schedulers"
config IOSCHED_NOOP
bool
default y
---help---
The no-op I/O scheduler is a minimal scheduler that does basic merging
and sorting. Its main uses include non-disk based block devices like
memory devices, and specialised software or hardware environments
that do their own scheduling and require only minimal assistance from
the kernel.
config IOSCHED_AS
tristate "Anticipatory I/O scheduler"
default y
---help---
The anticipatory I/O scheduler is the default disk scheduler. It is
generally a good choice for most environments, but is quite large and
complex when compared to the deadline I/O scheduler, it can also be
slower in some cases especially some database loads.
config IOSCHED_DEADLINE
tristate "Deadline I/O scheduler"
default y
---help---
The deadline I/O scheduler is simple and compact, and is often as
good as the anticipatory I/O scheduler, and in some database
workloads, better. In the case of a single process performing I/O to
a disk at any one time, its behaviour is almost identical to the
anticipatory I/O scheduler and so is a good choice.
config IOSCHED_CFQ
tristate "CFQ I/O scheduler"
default y
---help---
The CFQ I/O scheduler tries to distribute bandwidth equally
among all processes in the system. It should provide a fair
working environment, suitable for desktop systems.
choice
prompt "Default I/O scheduler"
default DEFAULT_AS
help
Select the I/O scheduler which will be used by default for all
block devices.
config DEFAULT_AS
bool "Anticipatory" if IOSCHED_AS=y
config DEFAULT_DEADLINE
bool "Deadline" if IOSCHED_DEADLINE=y
config DEFAULT_CFQ
bool "CFQ" if IOSCHED_CFQ=y
config DEFAULT_NOOP
bool "No-op"
endchoice
config DEFAULT_IOSCHED
string
default "anticipatory" if DEFAULT_AS
default "deadline" if DEFAULT_DEADLINE
default "cfq" if DEFAULT_CFQ
default "noop" if DEFAULT_NOOP
endmenu