lib/string & lib/memcpy: use GNU implementation.

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
Asynchronous I/O latency to a solid-state disk greatly increased
between the 2.6.32 and 3.0 kernels. By removing the plug from
do_io_submit(), we observed a 34% improvement in the I/O latency.

Unfortunately, at this level, we don't know if the request is to
a rotating disk or not.

Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Cc: linux-aio@kvack.org
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
sched: Prevent wakeup to enter critical section needlessly

Check the waitqueue task list to be non empty before entering the critical
section. This prevents locking the spin lock needlessly in case the queue
was empty, and therefor also prevent scheduling overhead on a PREEMPT_RT
system.

Signed-off-by: Ivo Sieben <meltedpianoman@gmail.com>
backported from Linux 3.5+ by faux123
timers: Avoid finding cpu for migration of running timers in __mod_timer()

Currently we don't support migration of currently running timers. Current code
flow in __mod_timer() is:
- Find a cpu where we should migrate the timer
- Check if timer is currently running
- If yes, don't migrate.

In this process, the first step is a unnecessary activiy, if the timer is
currently running. This patch tries to avoid it in such cases.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
backported from Linux 3.5+ by faux123
Added optimized ARM RWSEM algorithm.
Added optimized CRC32 algorithm.
otter defconfig: Enable optimized ARM RWSEM algorithm
staging: android: Reduced Android Logger RAM usage

Change-Id: Iab33abb47f17b175ebd3da5f17c926c1929f060c

Conflicts:
	drivers/staging/android/logger.c
iosched: prevent aliased requests from starving other I/O

Hi, Jens,

If you recall, I posted an RFC patch for this back in July of last year:
http://lkml.org/lkml/2010/7/13/279

The basic problem is that a process can issue a never-ending stream of
async direct I/Os to the same sector on a device, thus starving out
other I/O in the system (due to the way the alias handling works in both
cfq and deadline).  The solution I proposed back then was to start
dispatching from the fifo after a certain number of aliases had been
dispatched.  Vivek asked why we had to treat aliases differently at all,
and I never had a good answer.  So, I put together a simple patch which
allows aliases to be added to the rb tree (it adds them to the right,
though that doesn't matter as the order isn't guaranteed anyway).  I
think this is the preferred solution, as it doesn't break up time slices
in CFQ or batches in deadline.  I've tested it, and it does solve the
starvation issue.  Let me know what you think.

Cheers,
Jeff

Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
vr-iosched: Fix build
staging: android: Set lowmem debug level to 1

Change-Id: I41f3d47e5857016c061fc31cb7d7de24ba67f582
staging: android: Import lowmemorykiller from android-3.4

Change-Id: I9f7820b41d895d9bbb007fc258975acda6ce4f75
random: entropy tweaks are all the rage nowadays

use nonblocking for all.  Read this web page:
http://lwn.net/Articles/489734/
random: prevent add_input from doing anything
Revert "random: prevent add_input from doing anything"

This reverts commit 106905a9743cd694660473003595a53fc0bd0f66.
Revert "random: entropy tweaks are all the rage nowadays"

This reverts commit ed7bb15935d2e23b5587f9fe8cdf3cdb0626caf0.
Linux 3.0.60
block: prepare I/O context code for BFQ-v5r1 for 3.0

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>
block: cgroups, kconfig, build bits for BFQ-v5r1-3.0

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.

Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
block: introduce the BFQ-v5r1 I/O sched for 3.0

Add the BFQ-v5r1 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.

Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>