sched: Improve scalability via 'CPU buddies', which withstand random perturbations

Traversing an entire package is not only expensive, it also leads to tasks
bouncing all over a partially idle and possible quite large package.  Fix
that up by assigning a 'buddy' CPU to try to motivate.  Each buddy may try
to motivate that one other CPU, if it's busy, tough, it may then try its
SMT sibling, but that's all this optimization is allowed to cost.

Sibling cache buddies are cross-wired to prevent bouncing.

4 socket 40 core + SMT Westmere box, single 30 sec tbench runs, higher is better:

 clients     1       2       4        8       16       32       64      128
 ..........................................................................
 pre        30      41     118      645     3769     6214    12233    14312
 post      299     603    1211     2418     4697     6847    11606    14557

A nice increase in performance.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

Conflicts:

	kernel/sched/core.c
	kernel/sched/fair.c
mmc: core: Fix possbile memory leak

Fix possible memory leak detected by kmemleak:

unreferenced object 0xc0f80f00 (size 64):
  comm "swapper/0", pid 1, jiffies 4294937508 (age 82.980s)
  hex dump (first 32 bytes):
    6d 6d 63 30 5f 64 65 74 65 63 74 00 72 79 2e 68  mmc0_detect.ry.h
    00 07 00 00 68 77 63 61 70 2e 68 00 02 00 00 70  ....hwcap.h....p
  backtrace:
    [<c010a1fc>] __kmalloc+0x164/0x220
    [<c01e1630>] kvasprintf+0x38/0x58
    [<c01e1668>] kasprintf+0x18/0x24
    [<c02fcf60>] mmc_alloc_host+0x114/0x1b4
    [<c0311c84>] msmsdcc_probe+0xc14/0x1fd8
    [<c022b40c>] platform_drv_probe+0x14/0x18
    [<c022a144>] driver_probe_device+0x144/0x334
    [<c022a394>] __driver_attach+0x60/0x84
    [<c022884c>] bus_for_each_dev+0x4c/0x78
    [<c0229720>] bus_add_driver+0xd0/0x250
    [<c022a884>] driver_register+0x9c/0x128
    [<c00086bc>] do_one_initcall+0x90/0x160
    [<c06d1904>] kernel_init+0xe8/0x1a4
    [<c000ee4c>] kernel_thread_exit+0x0/0x8
    [<ffffffff>] 0xffffffff

Change-Id: I3b29d71463af849a072cabbe56637adf6db6d0da
Signed-off-by: Sujit Reddy Thumma <sthumma@codeaurora.org>

Conflicts:
	include/linux/mmc/host.h

+ testing ...

Conflicts:

	include/linux/mmc/host.h
ashmem: fix deadlock when system is low on memory
When system is low on memory, allocating memory while holding the
ashmem_mutex may try to directly reclaim memory. Then ashmem_shrink()
is called in same thread. It will deadlock at acquiring ashmem_mutex.
This change lets ashmem_shrink() return failure if ashmem_mutex is not
available. Memory will be reclaimed from others.
Add ARM CPU topology

** This is a combination of 12 commits.
** The first commit's message is:
Add ARM cpu topology definition

(Patch accepted by Russell for 3.1:
http://www.spinics.net/lists/arm-kernel/msg131273.html)

The affinity between ARM processors is defined in the MPIDR register.
We can identify which processors are in the same cluster,
and which ones have performance interdependency. We can define the
cpu topology of ARM platform, that is then used by sched_mc and sched_smt.

The default state of sched_mc and sched_smt config is disable.
When enabled, the behavior of the scheduler can be modified with
sched_mc_power_savings and sched_smt_power_savings sysfs interfaces.

Changes since v4 :
*  Remove unnecessary parentheses and blank lines

Changes since v3 :
* Update the format of printk message
* Remove blank line

Changes since v2 :
* Update the commit message and some comments

Changes since v1 :
* Update the commit message
* Add read_cpuid_mpidr in arch/arm/include/asm/cputype.h
* Modify header of arch/arm/kernel/topology.c
* Modify tests and manipulation of MPIDR's bitfields
* Modify the place and dependancy of the config
* Modify Noop functions

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
Signed-off-by: Amit Kucheria <amit.kucheria@verdurent.com>
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>

** This is the 2nd commit message:

ARM: cpu topology: fix warning

kernel/sched.c:7354:2: warning: initialization from incompatible pointer type

Align cpu_coregroup_mask prototype interface with sched_domain_mask_f typedef
use int cpu instead of unsigned int cpu

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>

** This is the 3rd commit message:

ARM: cpu topology: Add update_cpu_topology function

arch_update_cpu_topology function is called by the scheduler
before building its sched_domain hierarchy. Prepare the update
of the cpu topology masks in this function in addition to set
it in the the store_cpu_topology which is executed only once per cpu.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>

** This is the 4th commit message:

ARM: cpu topology: modify cpu topology

Modify the CPU topology policy according to the sched_mc level and the cortex family

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>

** This is the 5th commit message:

ARM: scheduler: add a cpu_power function

Add an architecture specific function for setting cpu_power

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>

** This is the 6th commit message:

ARM: cpu topology: Modify cpu_power according to sched_mc level

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>

** This is the 7th commit message:

ARM: cpu topology: Modify cpu_power according to cpufreq

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>

** This is the 8th commit message:

ARM: cpu topology: Add asym topology flag for using cpu0 1st

Modify the CPU sched_domain flags in powersave mode for using the cpu0 in ched_mc powersave mode

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>

** This is the 9th commit message:

ARM: cpu topology: Add debugfs interface for cpu_power

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>

** This is the 10th commit message:

sched: Ensure cpu_power periodic update

With a lot of small tasks, the softirq sched is nearly never called
when no_hz is enable. The load_balance is mainly called with
the newly_idle mode which doesn't update the cpu_power.
Add a next_update field which ensures a maximum update period when
there is short activity

Signed-off-by: Vincent Guittot <vincent.guittot at linaro.org>

** This is the 11th commit message:

ARM: scheduler: add a missing part
This fix adds a missing part in the [RFC 07/11].

Signed-off-by: Vincent Guittot <vincent.guittot at linaro.org>

** This is the 12th commit message:

sched: nohz_idle_balance

clear rq->nohz_balance_kick before returning

if idle equals CPU_IDLE, we return and could let nohz_balance_kick set
rq->nohz_balance_kick is tested in nohz_balancer_kick before triggering a SOFTIRQ on the ilb.
If this_rq->nohz_balance_kick stay to 1, the ilb will no be triggered until it wakes up and performs a normal load_balance which will clear the nohz_balance_kick

Signed-off-by: Vincent Guittot <vincent.guittot at linaro.org>

Conflicts:

	arch/arm/kernel/smp.c
defconfig : enable topology
touchscreen: tweak some initialization parameters for better UI response
Signed-off-by: faux123 <reioux@gmail.com>
block/deadline: tweaked for better performance on android
Signed-off-by: faux123 <reioux@gmail.com>
activate msm_mpdecision and use old version mpdecision
defconfig : beta