Revert "Block: Added VR IO scheduler."

This reverts commit 80fb27d66e25adcdc0389ecee1481b35f2d1f2b7.
Revert "Block: Added SIO IO scheduler."

This reverts commit 535aef19ab4df84e2452c5002338c9504404f603.
Revert "Block: Added ROW IO scheduler."

This reverts commit 490010911c3bc816c060ce46621be680e6e67424.
block: introduce the BFQ-v5 I/O sched for 3.0

Add the BFQ-v5 I/O scheduler to 3.0.
The general structure is borrowed from CFQ, as much code. A (bfq_)queue is
associated to each task doing I/O on a device, and each time a scheduling
decision has to be taken a queue is selected and it is 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 very low latency.

    - Latency guarantees are preserved also in presence of NCQ.

    - High throughput with flash-based devices, while still preserving
      latency guarantees.

    - Useful features borrowed from CFQ: cooperating-queues merging (with
      some additional optimizations with respect to the original CFQ version),
      static fallback queue for OOM.

    - BFQ supports full hierarchical scheduling, exporting a cgroups
      interface.  Each node has a full scheduler, so each group can
      be assigned its own ioprio and an ioprio_class.

    - If the cgroups interface is used, weights can be explictly assigned,
      otherwise ioprio values are mapped to weights using 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 weights of each queue. A very thin extra bandwidth
      is however guaranteed to the Idle class, to prevent it from starving.

Add a Kconfig option and do the related Makefile changes to compile
the BFQ I/O scheduler.  Also let the cgroups subsystem know about the
BFQ I/O controller.

BFQ uses struct cfq_io_context to store its per-process per-device data,
reusing the same code for cic handling of CFQ.  The code is not shared
ATM to minimize the impact of these patches.

This patch introduces a new hlist to each io_context to store all the
cic's allocated by BFQ to allow calling the right destructor on module
unload; the radix tree used for cic lookup needs to be duplicated
because it can contain dead keys inserted by a scheduler and later
retrieved by the other one.

Update the io_context exit and free paths to take care also of
the BFQ cic's.

Change the type of cfqq inside struct cfq_io_context to void *
to use it also for BFQ per-queue data.

A new bfq-specific ioprio_changed field is necessary, too, to avoid
clobbering cfq's one, so switch ioprio_changed to a bitmap, with one
element per scheduler.

Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: KalimochoAz <calimochoazucarado@gmail.com>
block: Add Zen I/O scheduler

Similar to SIO, primarily based on no-op and deadline. Intended to be mostly FCFS. Simpler than SIO in many ways, one of them being write requests/read requests have mostly the same priority.
block: Deadline i/o scheduler - added morfic's 1:1 secret sauce
block: Add SIO I/O Scheduler
block: SIO i/o scheduler - Changed parameters
block: add row io scheduler
block: Update ROW i/o scheduler

The ROW scheduling algorithm will be used in mobile devices as default
block layer IO scheduling algorithm. ROW stands for "READ Over WRITE"
which is the main requests dispatch policy of this algorithm.

The ROW IO scheduler was developed with the mobile devices needs in
mind. In mobile devices we favor user experience upon everything else,
thus we want to give READ IO requests as much priority as possible.

In mobile devices we won’t have AS much parallel threads as on desktops.
Usually it’s a single thread or at most 2 simultaneous working threads
for read & write. Favoring READ requests over WRITEs decreases the READ
latency greatly. The main idea of the ROW scheduling policy is:
If there are READ requests in pipe - dispatch them but don't starve
the WRITE requests too much.
block: Add VR I/O scheduler
block: Increase idling time for ROW iosched
block: Update Makefile and Kconfig for new I/O Schedulers
drivers: staging: LMK - Added screen on/off values & tuning
updater-script: Remove noob stuff on flash
drivers: cpufreq: Add more governors
Linux 3.0.76