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* thermal: power_allocator: round the division when divvying up powerJavi Merino2015-05-111-1/+2
| | | | | | | | | | | | | | | | | In situations where there is an uneven number of cooling devices, the division of power among them can lead to a milliwatt being dropped on the floor due to rounding errors. This doesn't sound like a lot, but some devices only grant the lowest cooling device state for their maximum power. So for instance, if the granted_power is the maximum power and all devices are getting their maximum power, one would get max_power - 1, making it choose cooling device state 1, instead of 0. Round the division to make the calculation more accurate. Cc: Zhang Rui <rui.zhang@intel.com> Cc: Eduardo Valentin <edubezval@gmail.com> Signed-off-by: Javi Merino <javi.merino@arm.com> Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
* thermal: add trace events to the power allocator governorJavi Merino2015-05-041-2/+20
| | | | | | | | | | | | | Add trace events for the power allocator governor and the power actor interface of the cpu cooling device. Cc: Zhang Rui <rui.zhang@intel.com> Cc: Eduardo Valentin <edubezval@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Javi Merino <javi.merino@arm.com> Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
* thermal: introduce the Power Allocator governorJavi Merino2015-05-041-0/+520
The power allocator governor is a thermal governor that controls system and device power allocation to control temperature. Conceptually, the implementation divides the sustainable power of a thermal zone among all the heat sources in that zone. This governor relies on "power actors", entities that represent heat sources. They can report current and maximum power consumption and can set a given maximum power consumption, usually via a cooling device. The governor uses a Proportional Integral Derivative (PID) controller driven by the temperature of the thermal zone. The output of the controller is a power budget that is then allocated to each power actor that can have bearing on the temperature we are trying to control. It decides how much power to give each cooling device based on the performance they are requesting. The PID controller ensures that the total power budget does not exceed the control temperature. Cc: Zhang Rui <rui.zhang@intel.com> Cc: Eduardo Valentin <edubezval@gmail.com> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Signed-off-by: Javi Merino <javi.merino@arm.com> Signed-off-by: Eduardo Valentin <edubezval@gmail.com>
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