block: introduce the BFQ-v5 I/O sched for 3.3

Includes the 3.0 fix

Add the BFQ-v5 I/O scheduler to 3.3.
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.

Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Dan Trifan <jimsth@gmail.com>
block/bfq-iosched.c: BFQ scheduler tweaks

Thanks pkgnex, Khrushy frrm Franco dev team & boype

Signed-off-by: Dan Trifan <jimsth@gmail.com>
defconfig: enable BFQ io scheduler and make it default

Signed-off-by: Dan Trifan <jimsth@gmail.com>
block: strict rq_affinity

Some systems benefit from completions always being steered to the strict
requester cpu rather than the looser "per-socket" steering that
blk_cpu_to_group() attempts by default. This is because the first
CPU in the group mask ends up being completely overloaded with work,
while the others (including the original submitter) has power left
to spare.

Allow the strict mode to be set by writing '2' to the sysfs control
file. This is identical to the scheme used for the nomerges file,
where '2' is a more aggressive setting than just being turned on.

echo 2 > /sys/block/<bdev>/queue/rq_affinity

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Roland Dreier <roland@purestorage.com>
Tested-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: Dan Trifan <jimsth@gmail.com>
arm: Allow CPU-supported unaligned accesses

This change reconfigures the CPU to allow CPU-supported unaligned
accesses, which are generally faster than software-only fixups,
resulting in fewer alignment exceptions.

Signed-off-by: Brent DeGraaf <bdegraaf@codeaurora.org>
modified by faux123 for omap

Signed-off-by: Dan Trifan <jimsth@gmail.com>
defconfig: enable CONFIG_ALLOW_CPU_ALIGNMENT

Signed-off-by: Dan Trifan <jimsth@gmail.com>
CONFIG_SCHED_AUTOGROUP

Signed-off-by: Dan Trifan <jimsth@gmail.com>