ghost: Bring all CPUs online on early init

* Speed up boot

Signed-off-by: Zhao Wei Liew <zhaoweiliew@gmail.com>
cpufreq: interactive: Make window alignment optional

Make sampling window alignment optional when scheduler inputs
are not enabled.

Change-Id: If69c111a3efe219cdd1e38c1f46f03404789c0bb
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>
msm: hotplug: Default total CPUs to 2

Signed-off-by: Zhao Wei Liew <zhaoweiliew@gmail.com>
cpufreq: cpu-boost: Add cpu-boost driver

When certain bursty and important events take place, it might take a while
for the current cpufreq governor to notice the new load and react to it.
That would result in poor user experience. To alleviate this, the cpu-boost
driver boosts the frequency of a CPU for a short duration to maintain good
user experience while the governor catches up.

Specifically, this commit deals with ensuring that when "important" tasks
migrate from a fast CPU to a slow CPU, the frequency of the slow CPU is
boosted to be at least as high as the fast CPU for a short duration.

Since this driver enforces the boost by hooking into standard cpufreq
ADJUST notifiers, it has several advantages:
- More portable across kernel versions where the cpufreq internals might
  have been rewritten.
- Governor agnostic and hence works with multiple governors like
  conservative, ondemand, interactive, etc.
- Does not affect the sampling period/logic of existing governors.
- Can have the boost period adjusted independent of governor sampling
  period.

Change-Id: Ibd814a20043d0aba64ee7637a4a79b9ffa1b0991
Signed-off-by: Saravana Kannan <skannan@codeaurora.org>

Conflicts:
	drivers/cpufreq/Kconfig
	drivers/cpufreq/Makefile
cpufreq: Add a sync limit to cpu-boost

Perform frequency synchronization only when source CPU's frequency
is less than sync_threshold, else sync to the sync_threshold.

Change-Id: I544c414568d4e015b80ce5891dd215275bac95da
Signed-off-by: Rohit Gupta <rohgup@codeaurora.org>
cpufreq: Add Input Boost feature to the cpu-boost driver

On incoming input events boost the frequency of all online cpus
for at least input_boost_ms ms. This is accomplished by changing
the policy->min of all the online cpus to input_boost_freq.

Change-Id: Idb0ab75d68ae4ceff259cbbaaec1a9bb3bc871d3
Signed-off-by: Rohit Gupta <rohgup@codeaurora.org>
cpufreq: cpu-boost: Resolve deadlock when waking up sync thread

CPU boost driver receives notification from scheduler when threads
migrate towards a cpu and in turn wakes up a sync thread associated
with that cpu to handle any required frequency transitions. The wakeup
call however can lead to a deadlock inside scheduler under some
circumstance. The deadlock is seen when sync thread is the only thread
running on a cpu and goes to sleep (say by calling wait_event() ->
schedule()). Midway through this sleep (schedule()) call, while cpu is
still running in context of sync thread, scheduler attempts a load
balance (realizing that cpu is about to become idle) which can result
in tasks being migrated towards the cpu going idle. This will cause
migration notification to be issued and in turn a wakeup on sync
thread. The wakeup call however gets stuck in below while() loop
inside scheduler:

try_to_wake_up(struct task_struct *p, ...)
{

        /*
         * If the owning (remote) cpu is still in the middle of
	 * schedule() with this task as prev, wait until its done
	 * referencing the task.
         */
	while (p->on_cpu)
		cpu_relax();

}

A possible fix could be to teach try_to_wake_up() about this
special case. Another fix, implemented in this patch and that helps
minimize scheduler changes, is to have cpu boost driver not issue a
wakeup under this special circumstance, which was found to occur very
infrequently.

Change-Id: I92bc68a22d51595a208673fe2a1eedfa97004f9e
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
cpufreq: cpu-boost: Fix queue_delayed_work_on() race with hotplug

Calling queue_delayed_work_on() on a CPU that's in the process of getting
hotplugged out can result in that CPU infinitely looping in
msm_pm_wait_cpu_shutdown(). If queue_delayed_work_on() is called after the
CPU is hotplugged out, it could wake up the CPU without going through the
hotplug path and cause instability. To avoid this, make sure the CPU is and
stays online while queuing a work on it.

Change-Id: I1b4aae3db803e476b1a7676d08f495c1f38bb154
Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
cpufreq: cpu-boost: Fix deadlock in wake_up of sync threads

If wake_up() is called on the current task on a CPU, the call will wait
until the current task is switched out before it wakes it up again and
returns.

The sync notifier for a CPU always runs on that CPU.

These two together can result in a deadlock if the sync notifier on CPU A
tries to wake up the sync thread of CPU A as it goes to sleep (is the
current task). A previous commit fixed this by adding a check to the sync
notifier to not wake up the sync thread of CPU A if it's the current task.

But this is still not sufficient to prevent deadlocks.

Sync thread of CPU A could be the current task on CPU B and sync thread of
CPU B could be the current task on CPU A.  At this point, if sync notifier
of CPU A and B try to wake up the sync threads of CPU A and B, it will
result in CPU A waiting for the current task in CPU B to get switched out
and CPU B waiting for the current task in CPU A to get switched out.  This
will result in a deadlock.

Prevent this scenario from happening by pinning the sync threads of each
CPU to run on that CPU. By doing this, we guarantee that sync notifiers
will only try to wake up sync threads running on that CPU. The fix added by
"cpufreq: cpu-boost: Resolve deadlock when waking up sync thread" ensures a
deadlock doesn't happen when a sync notifier tries to wake up a sync thread
running on that CPU.

Change-Id: I864e545529722a23886dd5a82f66089155d2d193
Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
cpufreq: cpu-boost: Don't register for cpufreq notifiers too early

The cpufreq notifiers should be registered only after all the data
structures used in the notifier callbacks have been initialized. So, move
the cpufreq notifier registration to a later point in the init function.

Change-Id: I043ab5bc0ebb98164c40549fe151a8d801c8c186
Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
cpufreq: cpu-boost: Re-issue boosts above minimum frequency

Frequency boosts where the source CPU frequency is greater than CPU's
minimum frequency should always go through regardless of the destination
CPU's current frequency. This fixes a performance issue where the governor
lowers the CPU frequency shortly after a thread is migrated to it because
the boost wasn't re-issued.

Change-Id: I449545a688d84b0a6e834f5a51dcb499caa84d29
Signed-off-by: Patrick Cain <pcain@codeaurora.org>
cpufreq: Sync on thread migration optimizations

When threads migrate between CPUs the destination CPU will temporarily
have a boosted frequency and the source CPU will have a residual higher
frequency even though the load could have just been reduced. To avoid
leaving CPUs at a high frequencies notify the source CPU after a thread
migration and make the interactive governor's timer reschedule
conditionally.

Change-Id: Id55055f2a116ca7ffd2a34dc3d0ec519c888a111
Signed-off-by: Patrick Cain <pcain@codeaurora.org>

Conflicts:
	drivers/cpufreq/cpufreq_interactive.c
cpufreq: cpu-boost: Use interruptible wait to not affect load average

Using the function wait_event in cpu_boost puts the
process enter to 'D' state which contribute to the
high load average. This change will put the process
boost_sync in the 'S' state (interruptible sleep)

Change-Id: Ie121adbe1fac1d2862ac5342bb97c7c926f7d7a8
CRs-Fixed: 655484
Signed-off-by: Swetha Chikkaboraiah <schikk@codeaurora.org>
Signed-off-by: Raghavendra Ambadas <rambad@codeaurora.org>
cpufreq: cpu-boost: Support separate input_boost_freq for different CPUs

Different types of CPUs could have different frequency to satisfy same
input workload. Add support for using different input_boost_freq on
different CPUs.

input_boost_freq now either takes a single number which applies to all
CPUs, or cpuid:freq pairs separated by space for different CPUs.

Change-Id: I20506a9fbdb4d532d94168bbd61744595bebc8e5
Signed-off-by: Junjie Wu <junjiew@codeaurora.org>

Conflicts:
	drivers/cpufreq/cpu-boost.c
cpufreq: cpu-boost: Use one work to remove input boost for all CPUs

Currently each CPU queues up its own work for removing input boost.
This is not really required as boost removal for all the CPUs can
be done at the same time. So this patch uses a single work to
remove input boost for all the CPUs and updates the policy for
the online ones.

Change-Id: I37c809f2f155548b1d8c1b9aa7626c8852b3acc6
Signed-off-by: Rohit Gupta <rohgup@codeaurora.org>

Conflicts:
	drivers/cpufreq/cpu-boost.c
sched: Make scheduler aware of cpu frequency state

Capacity of a cpu (how much performance it can deliver) is partly
determined by its frequency (P) state, both current frequency as well
as max frequency it can reach.  Knowing frequency state of cpus will
help scheduler optimize various functions such as tracking every
task's cpu demand and placing tasks on various cpus.

This patch has scheduler registering for cpufreq notifications to
become aware of cpu's frequency state. Subsequent patches will make
use of derived information for various purposes, such as task's scaled
load (cpu demand) accounting and task placement.

Change-Id: I376dffa1e7f3f47d0496cd7e6ef8b5642ab79016
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
sched: window-based load stats for tasks

Provide a metric per task that specifies how cpu bound a task is. Task
execution is monitored over several time windows and the fraction of
the window for which task was found to be executing or wanting to run
is recorded as task's demand. Windows over which task was sleeping are
ignored. We track last 5 recent windows for every task and the maximum
demand seen in any of the previous 5 windows (where task had some
activity) drives freq demand for every task.

A per-cpu metric (rq->cumulative_runnable_avg) is also provided which
is an aggregation of cpu demand of all tasks currently enqueued on it.
rq->cumulative_runnable_avg will be useful to know if cpu frequency
will need to be changed to match task demand.

Change-Id: Ib83207b9ba8683cd3304ee8a2290695c34f08fe2
Signed-off-by: Srivatsa Vaddagiri <vatsa@codeaurora.org>
sched: add notifier for cross-cpu migrations

Originally from Jeremy Fitzhardinge.

Change-Id: I3fac7f2aae60066082d5ecfb2830c83e22b3082c
Acked-by: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
cpufreq: cpu-boost: Introduce scheduler assisted load based syncs

Previously, on getting a migration notification cpu-boost changed
the scaling min of the destination frequency to match that of the
source frequency or sync_threshold whichever was minimum.

If the scheduler migration notification is extended with task load
(cpu demand) information, the cpu boost driver can use this load to
compute a suitable frequency for the migrating task. The required
frequency for the task is calculated by taking the load percentage
of the max frequency and no sync is performed if the load is less
than a particular value (migration_load_threshold).This change is
beneficial for both perf and power as demand of a task is taken into
consideration while making cpufreq decisions and unnecessary syncs
for lightweight tasks are avoided.

The task load information provided by scheduler comes from a
window-based load collection mechanism which also normalizes the
load collected by the scheduler to the max possible frequency
across all CPUs.

Change-Id: Id2ba91cc4139c90602557f9b3801fb06b3c38992
Signed-off-by: Rohit Gupta <rohgup@codeaurora.org>

Conflicts:
	drivers/cpufreq/cpu-boost.c
sched: Call the notify_on_migrate notifier chain for wakeups as well

Add a change to send notify_on_migrate hints on wakeups of
foreground tasks from scheduler if their load is above
wakeup_load_thresholds (default value is 60).
These hints can be used to choose an appropriate CPU frequency
corresponding to the load of the task being woken up.

Change-Id: Ieca413c1a8bd2b14a15a7591e8e15d22925c42ca
Signed-off-by: Rohit Gupta <rohgup@codeaurora.org>