sched: pack small tasks

During sched_domain creation, we define a pack buddy CPU if available.

On a system that share the powerline at all level, the buddy is set to -1

On a dual clusters / dual cores system which can powergate each core and
cluster independantly, the buddy configuration will be :
      | CPU0 | CPU1 | CPU2 | CPU3 |
-----------------------------------
buddy | CPU0 | CPU0 | CPU0 | CPU2 |

Small tasks tend to slip out of the periodic load balance.
The best place to choose to migrate them is at their wake up.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
nohz: Remove "Switched to NOHz mode" debugging messages

When performing cpu hotplug tests the kernel printk log buffer gets flooded
with pointless "Switched to NOHz mode..." messages. Especially when afterwards
analyzing a dump this might have removed more interesting stuff out of the
buffer.
Assuming that switching to NOHz mode simply works just remove the printk.

Change-Id: I1746f8c0119a512055716c3fd77a966b735ca49b
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Link: http://lkml.kernel.org/r/20110823112046.GB2540@osiris.boeblingen.de.ibm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jeff Ohlstein <johlstei@codeaurora.org>
touchscreen/mms_ts.c: Power OFF on screen_down - Power ON on screen_on
sched: secure access to other CPU statistics

The atomic update of runnable_avg_sum and runnable_avg_period are ensured
by their size and the toolchain. But we must ensure to not read an old value
for one field and a newly updated value for the other field. As we don't
want to lock other CPU while reading these fields, we read twice each fields
and check that no change have occured in the middle.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
sched: pack small tasks: fix printk formating

Reported-by: Jon Medhurst <tixy@linaro.org>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>