sched: Fix select_idle_sibling() bouncing cow syndrome

If the previous CPU is cache affine and idle, select it.

The current implementation simply traverses the sd_llc domain,
taking the first idle CPU encountered, which walks buddy pairs
hand in hand over the package, inflicting excruciating pain.

1 tbench pair (worst case) in a 10 core + SMT package:

  pre   15.22 MB/sec 1 procs
  post 252.01 MB/sec 1 procs

Signed-off-by: Mike Galbraith <bitbucket@online.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1359371965.5783.127.camel@marge.simpson.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
ARM: fix warning caused by wrongly typed arm_dma_limit

arch/arm/mm/init.c: In function 'arm_memblock_init':
arch/arm/mm/init.c:380: warning: comparison of distinct pointer types lacks a cast

by fixing the typecast in its definition when DMA_ZONE is disabled.
This was missed in 4986e5c7c (ARM: mm: fix type of the arm_dma_limit
global variable).

Change-Id: Id076f2bebe307609265afdd4229181d2004c5f9c
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>
workqueue: don't use WQ_HIGHPRI for unbound workqueues

Unbound wqs aren't concurrency-managed and try to execute work items
as soon as possible.  This is currently achieved by implicitly setting
%WQ_HIGHPRI on all unbound workqueues; however, WQ_HIGHPRI
implementation is about to be restructured and this usage won't be
valid anymore.

Add an explicit chain-wakeup path for unbound workqueues in
process_one_work() instead of piggy backing on %WQ_HIGHPRI.

Change-Id: Iecd17a9935ee28f856d8b726bb4c296762922bed
Signed-off-by: Tejun Heo <tj@kernel.org>
Git-commit: 974271c485a4d8bb801decc616748f90aafb07ec
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>
Revert "workqueue: don't use WQ_HIGHPRI for unbound workqueues"

This reverts commit 8bc04eddd07c2214e5d5206075dd3d8ff7a4ed67.
Revert "mm: ksm: Optimize defaults"

This reverts commit c7bea78a56b8d36f0313a4dc29c815dd24a1b49a.
CHROMIUM: clocksource: allow clocksources to be selected earlier during boot

Global and per-CPU timers ought to be initialized once SMP initialization
is complete.  Although the clocksources associated with these timers may
not be registered until later in the boot process, they should be ready
to go once registered.  We'd like to stop using the super low-resolution
boot clocksource (jiffies) as soon as possible since devices may rely on
accurate timekeeping while being brought up during boot, so move
clocksource_done_booting() to arch_initcall time so that we can switch
to a higher-resolution clocksrouce earlier in the boot process.

TEST=Pit and Lumpy both still boot reliably.  Boot time on Pit improves
considerably:
Before: [    3.032967] VFS: Mounted root ...
After:  [    1.855936] VFS: Mounted root ...
Lumpy boot time improves very slightly:
Before: [    1.786347] VFS: Mounted root ...
After:  [    1.754297] VFS: Mounted root ...

Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Reviewed-by: Sonny Rao <sonnyrao@chromium.org>
Reviewed-by: Sameer Nanda <snanda@chromium.org>
Signed-off-by: Luis Cruz <ljc2491@gmail.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
block: Switch from BFQ-v7r2 for 3.4.0 to BFQ-v7r3 for 3.4.0

. IMPROVEMENT: Improved throughput boosting with NCQ-capable HDDs and
  random workloads. The mechanism that further boosts throghput with
  these devices and workloads is activated only in the cases where it
  does not cause any violation of throughput-distribution and latency
  guarantees.
. IMPROVEMENT: Generalized the computation of the parameters of the
  low-latency heuristic for interactive applications, so as to fit also
  slower storage devices. The purpose of this improvement is to preserve
  low-latency guarantees for interactive applications also on slower
  devices, such as portable hard disks, multimedia and SD cards.
. BUGFIX: Re-added MODULE_LICENSE macro.
. CODE IMPROVEMENTS: Small code cleanups; introduced a coherent naming
  scheme for all identifiers related to weight raising; refactored and
  optimized a few hot paths.

Signed-off-by: Paolo Valente <paolo.valente@unimore.it>
Signed-off-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
Reported-by: Mikhail Akushsky <namelles.one@gmail.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
mmc: core: fix block request queue hang during data crc errors

When data CRC errors occur during write transactions, mmc
block layer queries the card for successful writes. If the card
reports bytes requested as bytes successfully written, the mmc
block layer will end the request with blk_end_request(). If there
is a following async request pending for execution, the request
is thrown away while handling CRC errors leading to hang in
request queue. The hang is visible when user issues a sync()
system call.

The sequence of events are as follows -

mmcqd -> fetch a request -> send it to host driver -> fetch another
request -> wait for previous request to complete -> previous request
is in error -> skip sending current request to host driver and
do error handling for previous request in error.

During the last step, after error handling is completed the mmc
block layer does not requeue the current request which is skipped
and hence the request is infinitely stuck in the driver.

Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
mmc: core: get drive types supported by eMMC cards

Get the various drive types other than the default supported
by the card.

Signed-off-by: Krishna Konda <kkonda@codeaurora.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
workqueue: consider work function when searching for busy work items

To avoid executing the same work item concurrenlty, workqueue hashes
currently busy workers according to their current work items and looks
up the the table when it wants to execute a new work item.  If there
already is a worker which is executing the new work item, the new item
is queued to the found worker so that it gets executed only after the
current execution finishes.

Unfortunately, a work item may be freed while being executed and thus
recycled for different purposes.  If it gets recycled for a different
work item and queued while the previous execution is still in
progress, workqueue may make the new work item wait for the old one
although the two aren't really related in any way.

In extreme cases, this false dependency may lead to deadlock although
it's extremely unlikely given that there aren't too many self-freeing
work item users and they usually don't wait for other work items.

To alleviate the problem, record the current work function in each
busy worker and match it together with the work item address in
find_worker_executing_work().  While this isn't complete, it ensures
that unrelated work items don't interact with each other and in the
very unlikely case where a twisted wq user triggers it, it's always
onto itself making the culprit easy to spot.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Andrey Isakov <andy51@gmx.ru>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
lib: Proportions with flexible period

Implement code computing proportions of events of different type (like code in
lib/proportions.c) but allowing periods to have different lengths. This allows
us to have aging periods of fixed wallclock time which gives better proportion
estimates given the hugely varying throughput of different devices - previous
measuring of aging period by number of events has the problem that a reasonable
period length for a system with low-end USB stick is not a reasonable period
length for a system with high-end storage array resulting either in too slow
proportion updates or too fluctuating proportion updates.

Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
lib: Fix possible deadlock in flexible proportion code

When percpu counter function in fprop_new_period() is interrupted by an
interrupt while holding counter lock, it can cause deadlock when the
interrupt wants to take the lock as well. Fix the problem by disabling
interrupts when calling percpu counter functions.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
lib/flex_proportions.c: fix corruption of denominator in flexible proportions

When racing with CPU hotplug, percpu_counter_sum() can return negative
values for the number of observed events.

This confuses fprop_new_period(), which uses unsigned type and as a
result number of events is set to big *positive* number.  From that
moment on, things go pear shaped and can result e.g.  in division by
zero as denominator is later truncated to 32-bits.

This bug causes a divide-by-zero oops in bdi_dirty_limit() in Borislav's
3.6.0-rc6 based kernel.

Fix the issue by using a signed type in fprop_new_period().  That makes
us bail out from the function without doing anything (mistakenly)
thinking there are no events to age.  That makes aging somewhat
inaccurate but getting accurate data would be rather hard.

Signed-off-by: Jan Kara <jack@suse.cz>
Reported-by: Borislav Petkov <bp@amd64.org>
Reported-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
writeback: remove nr_pages_dirtied arg from balance_dirty_pages_ratelimited_nr()

There is no reason to pass the nr_pages_dirtied argument, because
nr_pages_dirtied value from the caller is unused in
balance_dirty_pages_ratelimited_nr().

Signed-off-by: Namjae Jeon <linkinjeon@gmail.com>
Signed-off-by: Vivek Trivedi <vtrivedi018@gmail.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
mm: export dirty_writeback_interval

Export 'dirty_writeback_interval' to make it visible to
file-systems. We are going to push superblock management down to
file-systems and get rid of the 'sync_supers' kernel thread completly.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>