With the powercap dtpm controller, we are able to plug devices with
power limitation features in the tree.
The following patch introduces the CPU power limitation based on the
energy model and the performance states.
The power limitation is done at the performance domain level. If some
CPUs are unplugged, the corresponding power will be subtracted from
the performance domain total power.
It is up to the platform to initialize the dtpm tree and add the CPU.
Here is an example to create a simple tree with one root node called
"pkg" and the CPU's performance domains.
static int dtpm_register_pkg(struct dtpm_descr *descr)
{
struct dtpm *pkg;
int ret;
pkg = dtpm_alloc(NULL);
if (!pkg)
return -ENOMEM;
ret = dtpm_register(descr->name, pkg, descr->parent);
if (ret)
return ret;
return dtpm_register_cpu(pkg);
}
static struct dtpm_descr descr = {
.name = "pkg",
.init = dtpm_register_pkg,
};
DTPM_DECLARE(descr);
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Tested-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
On the embedded world, the complexity of the SoC leads to an
increasing number of hotspots which need to be monitored and mitigated
as a whole in order to prevent the temperature to go above the
normative and legally stated 'skin temperature'.
Another aspect is to sustain the performance for a given power budget,
for example virtual reality where the user can feel dizziness if the
GPU performance is capped while a big CPU is processing something
else. Or reduce the battery charging because the dissipated power is
too high compared with the power consumed by other devices.
The userspace is the most adequate place to dynamically act on the
different devices by limiting their power given an application
profile: it has the knowledge of the platform.
These userspace daemons are in charge of the Dynamic Thermal Power
Management (DTPM).
Nowadays, the dtpm daemons are abusing the thermal framework as they
act on the cooling device state to force a specific and arbitrary
state without taking care of the governor decisions. Given the closed
loop of some governors that can confuse the logic or directly enter in
a decision conflict.
As the number of cooling device support is limited today to the CPU
and the GPU, the dtpm daemons have little control on the power
dissipation of the system. The out of tree solutions are hacking
around here and there in the drivers, in the frameworks to have
control on the devices. The common solution is to declare them as
cooling devices.
There is no unification of the power limitation unit, opaque states
are used.
This patch provides a way to create a hierarchy of constraints using
the powercap framework. The devices which are registered as power
limit-able devices are represented in this hierarchy as a tree. They
are linked together with intermediate nodes which are just there to
propagate the constraint to the children.
The leaves of the tree are the real devices, the intermediate nodes
are virtual, aggregating the children constraints and power
characteristics.
Each node have a weight on a 2^10 basis, in order to reflect the
percentage of power distribution of the children's node. This
percentage is used to dispatch the power limit to the children.
The weight is computed against the max power of the siblings.
This simple approach allows to do a fair distribution of the power
limit.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Tested-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Split intel_rapl.c to intel_rapl_common.c and intel_rapl_msr.c, where
intel_rapl_common.c contains the common code that can be used by both MSR
and MMIO interface.
intel_rapl_msr.c contains the implementation of RAPL MSR interface.
Reviewed-by: Pandruvada, Srinivas <srinivas.pandruvada@intel.com>
Tested-by: Pandruvada, Srinivas <srinivas.pandruvada@intel.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Add SPDX license identifiers to all Make/Kconfig files which:
- Have no license information of any form
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Initially, the cpu_cooling device for ARM was changed by adding a new
policy inserting idle cycles. The intel_powerclamp driver does a
similar action.
Instead of implementing idle injections privately in the cpu_cooling
device, move the idle injection code in a dedicated framework and give
the opportunity to other frameworks to make use of it.
The framework relies on the smpboot kthreads which handles via its
main loop the common code for hotplugging and [un]parking.
This code was previously tested with the cpu cooling device and went
through several iterations. It results now in split code and API
exported in the header file. It was tested with the cpu cooling device
with success.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
[ rjw: Rewrite of all comments ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The Intel Running Average Power Limit (RAPL) technology provides platform
software with the ability to monitor, control, and get notifications on
power usage.
This feature is present in all Sandy Bridge and later Intel processors.
Newer models allow more fine grained controls to be applied. In RAPL,
power control is divided into domains, which include package, DRAM
controller, CPU core (Power Plane 0), graphics uncore (power plane 1), etc.
The purpose of this driver is to expose the RAPL settings to userspace.
Overall, RAPL fits in the new powercap class driver in that platform
level power capping controls are exposed via this generic interface.
This driver is based on an earlier patch from Zhang Rui.
However, while the previous work was mainly focused on thermal monitoring
the focus here is on the usability from user space perspective.
References: https://lkml.org/lkml/2011/5/26/93
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The power capping framework providing a consistent interface between the
kernel and user space that allows power capping drivers to expose their
settings to user space in a uniform way.
The overall design of the framework is described in the documentation
added by the previous patch in this series.
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Daniel Lezcano