linux-toradex.git/kernel/sched/cpufreq_schedutil.c, branch v4.10-rc5

cpufreq: schedutil: Rectify comment in sugov_irq_work() function

2016-11-24T20:50:59+00:00

This patch rectifies a comment present in sugov_irq_work() function to
follow proper grammar.

Suggested-by: Ingo Molnar 
Signed-off-by: Viresh Kumar 
Acked-by: Ingo Molnar 
Signed-off-by: Rafael J. Wysocki

cpufreq: schedutil: irq-work and mutex are only used in slow path

2016-11-16T22:21:08+00:00

Execute the irq-work specific initialization/exit code only when the
fast path isn't available.

Signed-off-by: Viresh Kumar 
Signed-off-by: Rafael J. Wysocki

cpufreq: schedutil: move slow path from workqueue to SCHED_FIFO task

2016-11-16T22:21:08+00:00

If slow path frequency changes are conducted in a SCHED_OTHER context
then they may be delayed for some amount of time, including
indefinitely, when real time or deadline activity is taking place.

Move the slow path to a real time kernel thread. In the future the
thread should be made SCHED_DEADLINE. The RT priority is arbitrarily set
to 50 for now.

Hackbench results on ARM Exynos, dual core A15 platform for 10
iterations:

$ hackbench -s 100 -l 100 -g 10 -f 20

Before			After
---------------------------------
1.808			1.603
1.847			1.251
2.229			1.590
1.952			1.600
1.947			1.257
1.925			1.627
2.694			1.620
1.258			1.621
1.919			1.632
1.250			1.240

Average:

1.8829			1.5041

Based on initial work by Steve Muckle.

Signed-off-by: Steve Muckle 
Signed-off-by: Viresh Kumar 
Acked-by: Peter Zijlstra (Intel) 
Signed-off-by: Rafael J. Wysocki

cpufreq: schedutil: enable fast switch earlier

2016-11-16T22:21:08+00:00

The fast_switch_enabled flag will be used by both sugov_policy_alloc()
and sugov_policy_free() with a later patch.

Prepare for that by moving the calls to enable and disable it to the
beginning of sugov_init() and end of sugov_exit().

Signed-off-by: Viresh Kumar 
Signed-off-by: Rafael J. Wysocki

cpufreq: schedutil: Avoid indented labels

2016-11-16T22:21:07+00:00

Switch to the more common practice of writing labels.

Suggested-by: Peter Zijlstra 
Signed-off-by: Viresh Kumar 
Signed-off-by: Rafael J. Wysocki

cpufreq: schedutil: Add iowait boosting

2016-09-13T21:36:01+00:00

Modify the schedutil cpufreq governor to boost the CPU
frequency if the SCHED_CPUFREQ_IOWAIT flag is passed to
it via cpufreq_update_util().

If that happens, the frequency is set to the maximum during
the first update after receiving the SCHED_CPUFREQ_IOWAIT flag
and then the boost is reduced by half during each following update.

Signed-off-by: Rafael J. Wysocki 
Looks-good-to: Steve Muckle 
Acked-by: Peter Zijlstra (Intel)

cpufreq / sched: ignore SMT when determining max cpu capacity

2016-08-31T22:32:57+00:00

PELT does not consider SMT when scaling its utilization values via
arch_scale_cpu_capacity(). The value in rq->cpu_capacity_orig does
take SMT into consideration though and therefore may be smaller than
the utilization reported by PELT.

On an Intel i7-3630QM for example rq->cpu_capacity_orig is 589 but
util_avg scales up to 1024. This means that a 50% utilized CPU will show
up in schedutil as ~86% busy.

Fix this by using the same CPU scaling value in schedutil as that which
is used by PELT.

Signed-off-by: Steve Muckle 
Signed-off-by: Rafael J. Wysocki

cpufreq / sched: Pass flags to cpufreq_update_util()

2016-08-16T20:14:55+00:00

It is useful to know the reason why cpufreq_update_util() has just
been called and that can be passed as flags to cpufreq_update_util()
and to the ->func() callback in struct update_util_data.  However,
doing that in addition to passing the util and max arguments they
already take would be clumsy, so avoid it.

Instead, use the observation that the schedutil governor is part
of the scheduler proper, so it can access scheduler data directly.
This allows the util and max arguments of cpufreq_update_util()
and the ->func() callback in struct update_util_data to be replaced
with a flags one, but schedutil has to be modified to follow.

Thus make the schedutil governor obtain the CFS utilization
information from the scheduler and use the "RT" and "DL" flags
instead of the special utilization value of ULONG_MAX to track
updates from the RT and DL sched classes.  Make it non-modular
too to avoid having to export scheduler variables to modules at
large.

Next, update all of the other users of cpufreq_update_util()
and the ->func() callback in struct update_util_data accordingly.

Suggested-by: Peter Zijlstra 
Signed-off-by: Rafael J. Wysocki 
Acked-by: Peter Zijlstra (Intel) 
Acked-by: Viresh Kumar

cpufreq: schedutil: map raw required frequency to driver frequency

2016-07-21T20:28:21+00:00

The slow-path frequency transition path is relatively expensive as it
requires waking up a thread to do work. Should support be added for
remote CPU cpufreq updates that is also expensive since it requires an
IPI. These activities should be avoided if they are not necessary.

To that end, calculate the actual driver-supported frequency required by
the new utilization value in schedutil by using the recently added
cpufreq_driver_resolve_freq API. If it is the same as the previously
requested driver frequency then there is no need to continue with the
update assuming the cpu frequency limits have not changed. This will
have additional benefits should the semantics of the rate limit be
changed to apply solely to frequency transitions rather than to
frequency calculations in schedutil.

The last raw required frequency is cached. This allows the driver
frequency lookup to be skipped in the event that the new raw required
frequency matches the last one, assuming a frequency update has not been
forced due to limits changing (indicated by a next_freq value of
UINT_MAX, see sugov_should_update_freq).

Signed-off-by: Steve Muckle 
Reviewed-by: Viresh Kumar 
Signed-off-by: Rafael J. Wysocki

cpufreq: governor: Create cpufreq_policy_apply_limits()

2016-06-02T21:24:39+00:00

Create a new helper to avoid code duplication across governors.

Signed-off-by: Viresh Kumar 
Signed-off-by: Rafael J. Wysocki