2020-03-27 16:21:54 +00:00
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if BLOCK
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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_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. It will provide
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CSCAN service with FIFO expiration of requests, switching to
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a new point in the service tree and doing a batch of IO from there
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in case of expiry.
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2017-06-30 23:35:23 +00:00
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config IOSCHED_MAPLE
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tristate "Maple I/O scheduler"
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default y
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2020-03-27 16:21:54 +00:00
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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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and low latency working environment, suitable for both desktop
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and server systems.
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This is the default I/O scheduler.
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config CFQ_GROUP_IOSCHED
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bool "CFQ Group Scheduling support"
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depends on IOSCHED_CFQ && BLK_CGROUP
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default n
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---help---
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Enable group IO scheduling in CFQ.
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2014-09-15 05:07:32 +00:00
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config IOSCHED_SIO
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tristate "Simple I/O scheduler"
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default y
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---help---
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The Simple I/O scheduler is an extremely simple scheduler,
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based on noop and deadline, that relies on deadlines to
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ensure fairness. The algorithm does not do any sorting but
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basic merging, trying to keep a minimum overhead. It is aimed
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mainly for aleatory access devices (eg: flash devices).
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2020-03-27 16:21:54 +00:00
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2015-04-07 11:39:12 +00:00
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config IOSCHED_BFQ
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tristate "BFQ I/O scheduler"
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default n
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---help---
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The BFQ I/O scheduler tries to distribute bandwidth among
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all processes according to their weights.
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It aims at distributing the bandwidth as desired, independently of
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the disk parameters and with any workload. It also tries to
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guarantee low latency to interactive and soft real-time
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applications. If compiled built-in (saying Y here), BFQ can
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be configured to support hierarchical scheduling.
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block: introduce the BFQ-v7r11 I/O sched for 4.4.0
The general structure is borrowed from CFQ, as much of the code for
handling I/O contexts. Over time, several useful features have been
ported from CFQ as well (details in the changelog in README.BFQ). A
(bfq_)queue is associated to each task doing I/O on a device, and each
time a scheduling decision has to be made a queue is selected and served
until it expires.
- Slices are given in the service domain: tasks are assigned
budgets, measured in number of sectors. Once got the disk, a task
must however consume its assigned budget within a configurable
maximum time (by default, the maximum possible value of the
budgets is automatically computed to comply with this timeout).
This allows the desired latency vs "throughput boosting" tradeoff
to be set.
- Budgets are scheduled according to a variant of WF2Q+, implemented
using an augmented rb-tree to take eligibility into account while
preserving an O(log N) overall complexity.
- A low-latency tunable is provided; if enabled, both interactive
and soft real-time applications are guaranteed a very low latency.
- Latency guarantees are preserved also in the presence of NCQ.
- Also with flash-based devices, a high throughput is achieved
while still preserving latency guarantees.
- BFQ features Early Queue Merge (EQM), a sort of fusion of the
cooperating-queue-merging and the preemption mechanisms present
in CFQ. EQM is in fact a unified mechanism that tries to get a
sequential read pattern, and hence a high throughput, with any
set of processes performing interleaved I/O over a contiguous
sequence of sectors.
- BFQ supports full hierarchical scheduling, exporting a cgroups
interface. Since each node has a full scheduler, each group can
be assigned its own weight.
- If the cgroups interface is not used, only I/O priorities can be
assigned to processes, with ioprio values mapped to weights
with the relation weight = IOPRIO_BE_NR - ioprio.
- ioprio classes are served in strict priority order, i.e., lower
priority queues are not served as long as there are higher
priority queues. Among queues in the same class the bandwidth is
distributed in proportion to the weight of each queue. A very
thin extra bandwidth is however guaranteed to the Idle class, to
prevent it from starving.
Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
Signed-off-by: Arianna Avanzini <avanzini@google.com>
Signed-off-by: Luca Grifo <lg@linux.com>
Signed-off-by: djb77 <dwayne.bakewell@gmail.com>
2013-05-09 17:10:02 +00:00
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config BFQ_GROUP_IOSCHED
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2015-04-07 11:39:12 +00:00
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bool "BFQ hierarchical scheduling support"
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depends on CGROUPS && IOSCHED_BFQ=y
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default n
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---help---
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block: introduce the BFQ-v7r11 I/O sched for 4.4.0
The general structure is borrowed from CFQ, as much of the code for
handling I/O contexts. Over time, several useful features have been
ported from CFQ as well (details in the changelog in README.BFQ). A
(bfq_)queue is associated to each task doing I/O on a device, and each
time a scheduling decision has to be made a queue is selected and served
until it expires.
- Slices are given in the service domain: tasks are assigned
budgets, measured in number of sectors. Once got the disk, a task
must however consume its assigned budget within a configurable
maximum time (by default, the maximum possible value of the
budgets is automatically computed to comply with this timeout).
This allows the desired latency vs "throughput boosting" tradeoff
to be set.
- Budgets are scheduled according to a variant of WF2Q+, implemented
using an augmented rb-tree to take eligibility into account while
preserving an O(log N) overall complexity.
- A low-latency tunable is provided; if enabled, both interactive
and soft real-time applications are guaranteed a very low latency.
- Latency guarantees are preserved also in the presence of NCQ.
- Also with flash-based devices, a high throughput is achieved
while still preserving latency guarantees.
- BFQ features Early Queue Merge (EQM), a sort of fusion of the
cooperating-queue-merging and the preemption mechanisms present
in CFQ. EQM is in fact a unified mechanism that tries to get a
sequential read pattern, and hence a high throughput, with any
set of processes performing interleaved I/O over a contiguous
sequence of sectors.
- BFQ supports full hierarchical scheduling, exporting a cgroups
interface. Since each node has a full scheduler, each group can
be assigned its own weight.
- If the cgroups interface is not used, only I/O priorities can be
assigned to processes, with ioprio values mapped to weights
with the relation weight = IOPRIO_BE_NR - ioprio.
- ioprio classes are served in strict priority order, i.e., lower
priority queues are not served as long as there are higher
priority queues. Among queues in the same class the bandwidth is
distributed in proportion to the weight of each queue. A very
thin extra bandwidth is however guaranteed to the Idle class, to
prevent it from starving.
Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
Signed-off-by: Arianna Avanzini <avanzini@google.com>
Signed-off-by: Luca Grifo <lg@linux.com>
Signed-off-by: djb77 <dwayne.bakewell@gmail.com>
2013-05-09 17:10:02 +00:00
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Enable hierarchical scheduling in BFQ, using the blkio controller.
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2015-04-07 11:39:12 +00:00
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2016-08-01 11:05:34 +00:00
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config IOSCHED_FIOPS
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tristate "IOPS based I/O scheduler"
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default y
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---help---
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This is an IOPS based I/O scheduler. It will try to distribute
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IOPS equally among all processes in the system. It's mainly for
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Flash based storage.
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2016-09-05 10:29:36 +00:00
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config IOSCHED_FIFO
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tristate "FIFO I/O scheduler"
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default y
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---help---
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Fifo is similar to no-op I/O scheduler and it's a minimal scheduler that does basic merging
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and sorting. Ported from: https://github.com/AndroidDeveloperAlliance/ZenKernel_TUNA/blob/master/block/fifo-iosched.c
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2016-09-05 10:31:21 +00:00
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config IOSCHED_SIOPLUS
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tristate "Simple I/O scheduler plus"
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default y
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---help---
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The Simple I/O scheduler is an extremely simple scheduler,
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based on noop and deadline, that relies on deadlines to
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ensure fairness. The algorithm does not do any sorting but
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basic merging, trying to keep a minimum overhead. It is aimed
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mainly for aleatory access devices (eg: flash devices).
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2016-09-05 10:29:36 +00:00
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2016-09-05 10:32:48 +00:00
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config IOSCHED_TRIPNDROID
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tristate "Tripndroid"
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default y
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---help---
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The Trip N Droid scheduler
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2016-09-05 10:34:10 +00:00
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config IOSCHED_VR
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tristate "V(R) I/O scheduler"
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default y
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---help---
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Requests are chosen according to SSTF with a penalty of rev_penalty
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for switching head direction.
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2016-09-05 10:32:48 +00:00
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2016-09-05 10:35:15 +00:00
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config IOSCHED_ZEN
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tristate "Zen I/O scheduler"
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default y
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---help---
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FCFS, dispatches are back-inserted, deadlines ensure fairness.
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Should work best with devices where there is no travel delay.
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2020-03-27 16:21:54 +00:00
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choice
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prompt "Default I/O scheduler"
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default DEFAULT_CFQ
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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_DEADLINE
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bool "Deadline" if IOSCHED_DEADLINE=y
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config DEFAULT_CFQ
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bool "CFQ" if IOSCHED_CFQ=y
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2015-04-07 11:39:12 +00:00
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config DEFAULT_BFQ
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bool "BFQ" if IOSCHED_BFQ=y
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help
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Selects BFQ as the default I/O scheduler which will be
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used by default for all block devices.
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The BFQ I/O scheduler aims at distributing the bandwidth
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as desired, independently of the disk parameters and with
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any workload. It also tries to guarantee low latency to
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interactive and soft real-time applications.
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2016-08-01 11:05:34 +00:00
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config DEFAULT_FIOPS
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bool "FIOPS" if IOSCHED_FIOPS=y
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2020-03-27 16:21:54 +00:00
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config DEFAULT_NOOP
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bool "No-op"
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2014-09-15 05:07:32 +00:00
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config DEFAULT_SIO
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bool "SIO" if IOSCHED_SIO=y
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2016-09-05 10:29:36 +00:00
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config DEFAULT_FIFO
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bool "fifo" if IOSCHED_FIFO=y
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2016-09-05 10:31:21 +00:00
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config DEFAULT_SIOPLUS
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bool "SIOPLUS" if IOSCHED_SIOPLUS=y
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2016-09-05 10:32:48 +00:00
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config DEFAULT_TRIPNDROID
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bool "TRIPNDROID" if IOSCHED_TRIPNDROID=y
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2016-09-05 10:34:10 +00:00
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config DEFAULT_VR
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bool "V(R)" if IOSCHED_VR=y
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2016-09-05 10:35:15 +00:00
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config DEFAULT_ZEN
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bool "ZEN" if IOSCHED_ZEN=y
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2017-06-30 23:35:23 +00:00
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config DEFAULT_MAPLE
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bool "Maple" if IOSCHED_MAPLE=y
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2020-03-27 16:21:54 +00:00
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endchoice
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config DEFAULT_IOSCHED
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string
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default "deadline" if DEFAULT_DEADLINE
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default "cfq" if DEFAULT_CFQ
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2015-04-07 11:39:12 +00:00
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default "bfq" if DEFAULT_BFQ
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2016-08-01 11:05:34 +00:00
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default "fiops" if DEFAULT_FIOPS
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2020-03-27 16:21:54 +00:00
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default "noop" if DEFAULT_NOOP
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2014-09-15 05:07:32 +00:00
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default "sio" if DEFAULT_SIO
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2016-09-05 10:29:36 +00:00
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default "fifo" if DEFAULT_FIFO
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2016-09-05 10:31:21 +00:00
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default "sioplus" if DEFAULT_SIOPLUS
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2016-09-05 10:32:48 +00:00
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default "tripndroid" if DEFAULT_TRIPNDROID
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2016-09-05 10:34:10 +00:00
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default "vr" if DEFAULT_VR
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2016-09-05 10:35:15 +00:00
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default "zen" if DEFAULT_ZEN
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2017-06-30 23:35:23 +00:00
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default "maple" if DEFAULT_MAPLE
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2020-03-27 16:21:54 +00:00
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endmenu
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endif
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