defconfig: Enable cpu boost driver

Change-Id: I2a452e3e551a3c3d49cc6b3c866cca77056af030
Signed-off-by: Zhao Wei Liew <zhaoweiliew@gmail.com>
sched: provide per cpu-cgroup option to notify on migrations

On systems where CPUs may run asynchronously, task migrations
between CPUs running at grossly different speeds can cause
problems.

This change provides a mechanism to notify a subsystem
in the kernel if a task in a particular cgroup migrates to a
different CPU. Other subsystems (such as cpufreq) may then
register for this notifier to take appropriate action when
such a task is migrated.

The cgroup attribute to set for this behavior is
"notify_on_migrate" .

Change-Id: Ie1868249e53ef901b89c837fdc33b0ad0c0a4590
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
sched: remove migration notification from RT class

Commit 88a7e37d265 (sched: provide per cpu-cgroup option to
notify on migrations) added a notifier call when a task is moved
to a different CPU. Unfortunately the two call sites in the RT
sched class where this occurs happens with a runqueue lock held.
This can result in a deadlock if the notifier call attempts to do
something like wake up a task.

Fortunately the benefit of 88a7e37d265 comes mainly from notifying
on migration of non-RT tasks, so we can simply ignore the movements
of RT tasks.

CRs-Fixed: 491370
Change-Id: I8849d826bf1eeaf85a6f6ad872acb475247c5926
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
sched: Fix SCHED_HRTICK bug leading to late preemption of tasks

SCHED_HRTICK feature is useful to preempt SCHED_FAIR tasks on-the-dot
(just when they would have exceeded their ideal_runtime). It makes use
of a a per-cpu hrtimer resource and hence alarming that hrtimer should
be based on total SCHED_FAIR tasks a cpu has across its various cfs_rqs,
rather than being based on number of tasks in a particular cfs_rq (as
implemented currently). As a result, with current code, its possible for
a running task (which is the sole task in its cfs_rq) to be preempted
much after its ideal_runtime has elapsed, resulting in increased latency
for tasks in other cfs_rq on same cpu.

Fix this by alarming sched hrtimer based on total number of SCHED_FAIR
tasks a CPU has across its various cfs_rqs.

Change-Id: I1f23680a64872f8ce0f451ac4bcae28e8967918f
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
sched: fix reference to wrong cfs_rq

Commit 7db16c8c (sched: Fix SCHED_HRTICK bug leading to late preemption
of tasks) introduced a bug in sched_slice() calculation by using wrong
cfs_rq for tasks. rq->cfs was incorrectly used as task's cfs_rq, rather
than the correct one to which they belonged.

Fix the bug by using correct cfs_rq for tasks.

Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
sched: change WARN_ON_ONCE to WARN_ON in try_to_wake_up_local()

The WARN_ON_ONCE() calls at the beginning of try_to_wake_up_local()
were recently converted from BUG_ON() calls. If these hit it indicates
something is wrong and that may contribute to other system instability.
To eliminate the risk of an instance of one of these errors going
un-noticed because there was an earlier instance that occured long ago,
change to WARN_ON(). If there ever is a flood of these there are bigger
problems.

Change-Id: I392832e2b6ec24b3569b001b1af9ecd4ed6828e7
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
tracing/sched: add load balancer tracepoint

When doing performance analysis it can be useful to see exactly
what is going on with the load balancer - when it runs and why
exactly it may not be redistributing load.

This additional tracepoint will show the idle context of the
load balance operation (idle, not idle, newly idle), various
values from the load balancing operation, the final result,
and the new balance interval.

Change-Id: I9e5c97ae3878bea44e60d189ff3cec2275f2c75e
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
sched: Fix clear NOHZ_BALANCE_KICK

I have faced a sequence where the Idle Load Balance was sometime not
triggered for a while on my platform, in the following scenario:

 CPU 0 and CPU 1 are running tasks and CPU 2 is idle

 CPU 1 kicks the Idle Load Balance
 CPU 1 selects CPU 2 as the new Idle Load Balancer
 CPU 2 sets NOHZ_BALANCE_KICK for CPU 2
 CPU 2 sends a reschedule IPI to CPU 2

 While CPU 3 wakes up, CPU 0 or CPU 1 migrates a waking up task A on CPU 2

 CPU 2 finally wakes up, runs task A and discards the Idle Load Balance
       task A quickly goes back to sleep (before a tick occurs on CPU 2)
 CPU 2 goes back to idle with NOHZ_BALANCE_KICK set

Whenever CPU 2 will be selected as the ILB, no reschedule IPI will be sent
because NOHZ_BALANCE_KICK is already set and no Idle Load Balance will be
performed.

We must wait for the sched softirq to be raised on CPU 2 thanks to another
part the kernel to come back to clear NOHZ_BALANCE_KICK.

The proposed solution clears NOHZ_BALANCE_KICK in schedule_ipi if
we can't raise the sched_softirq for the Idle Load Balance.

Change since V1:

- move the clear of NOHZ_BALANCE_KICK in got_nohz_idle_kick if the ILB
  can't run on this CPU (as suggested by Peter)

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1370419991-13870-1-git-send-email-vincent.guittot@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Git-commit: 873b4c65b519fd769940eb281f77848227d4e5c1
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
[smuckle@codeaurora.org: minor merge resolution for 3.4 in scheduler_ipi()]
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>
Change-Id: I3548612057cccc2ecc29429c129c44183083831f
sched/debug: Make sysrq prints of sched debug data optional

Calls to sysrq_sched_debug_show() can yield rather verbose output
which contributes to log spew and, under heavy load, may increase
the chances of a watchdog bark.

Make printing of this data optional with the introduction of a
new Kconfig, CONFIG_SYSRQ_SCHED_DEBUG.

Change-Id: I5f54d901d0dea403109f7ac33b8881d967a899ed
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>