if BLOCK 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_DEADLINE tristate "Deadline I/O scheduler" default y ---help--- The deadline I/O scheduler is simple and compact. It will provide CSCAN service with FIFO expiration of requests, switching to a new point in the service tree and doing a batch of IO from there in case of expiry. config IOSCHED_CFQ tristate "CFQ I/O scheduler" # If BLK_CGROUP is a module, CFQ has to be built as module. depends on (BLK_CGROUP=m && m) || !BLK_CGROUP || BLK_CGROUP=y default y ---help--- The CFQ I/O scheduler tries to distribute bandwidth equally among all processes in the system. It should provide a fair and low latency working environment, suitable for both desktop and server systems. This is the default I/O scheduler. Note: If BLK_CGROUP=m, then CFQ can be built only as module. config CFQ_GROUP_IOSCHED bool "CFQ Group Scheduling support" depends on IOSCHED_CFQ && BLK_CGROUP default n ---help--- Enable group IO scheduling in CFQ. config IOSCHED_ROW tristate "ROW I/O scheduler" default y ---help--- The ROW I/O scheduler gives priority to READ requests over the WRITE requests when dispatching, without starving WRITE requests. Requests are kept in priority queues. Dispatching is done in a RR manner when the dispatch quantum for each queue is calculated according to queue priority. Most suitable for mobile devices. config IOSCHED_SIO tristate "Simple I/O scheduler" default y ---help--- The Simple I/O scheduler is an extremely simple scheduler, based on noop and deadline, that relies on deadlines to ensure fairness. The algorithm does not do any sorting but basic merging, trying to keep a minimum overhead. It is aimed mainly for aleatory access devices (eg: flash devices). choice prompt "Default I/O scheduler" default DEFAULT_CFQ help Select the I/O scheduler which will be used by default for all block devices. config DEFAULT_DEADLINE bool "Deadline" if IOSCHED_DEADLINE=y config DEFAULT_CFQ bool "CFQ" if IOSCHED_CFQ=y config DEFAULT_ROW bool "ROW" if IOSCHED_ROW=y config DEFAULT_SIO bool "SIO" if IOSCHED_SIO=y config DEFAULT_NOOP bool "No-op" endchoice config DEFAULT_IOSCHED string default "deadline" if DEFAULT_DEADLINE default "cfq" if DEFAULT_CFQ default "row" if DEFAULT_ROW default "sio" if DEFAULT_SIO default "noop" if DEFAULT_NOOP endmenu endif