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Several subsystems in the kernel (task scheduler and/or thermal at the
time of writing) can benefit from knowing about the energy consumed by
CPUs. Yet, this information can come from different sources (DT or
firmware for example), in different formats, hence making it hard to
exploit without a standard API.
As an attempt to address this, introduce a centralized Energy Model
(EM) management framework which aggregates the power values provided
by drivers into a table for each performance domain in the system. The
power cost tables are made available to interested clients (e.g. task
scheduler or thermal) via platform-agnostic APIs. The overall design
is represented by the diagram below (focused on Arm-related drivers as
an example, but applicable to any architecture):
+---------------+ +-----------------+ +-------------+
| Thermal (IPA) | | Scheduler (EAS) | | Other |
+---------------+ +-----------------+ +-------------+
| | em_pd_energy() |
| | em_cpu_get() |
+-----------+ | +--------+
| | |
v v v
+---------------------+
| |
| Energy Model |
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| Framework |
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+---------------------+
^ ^ ^
| | | em_register_perf_domain()
+----------+ | +---------+
| | |
+---------------+ +---------------+ +--------------+
| cpufreq-dt | | arm_scmi | | Other |
+---------------+ +---------------+ +--------------+
^ ^ ^
| | |
+--------------+ +---------------+ +--------------+
| Device Tree | | Firmware | | ? |
+--------------+ +---------------+ +--------------+
Drivers (typically, but not limited to, CPUFreq drivers) can register
data in the EM framework using the em_register_perf_domain() API. The
calling driver must provide a callback function with a standardized
signature that will be used by the EM framework to build the power
cost tables of the performance domain. This design should offer a lot of
flexibility to calling drivers which are free of reading information
from any location and to use any technique to compute power costs.
Moreover, the capacity states registered by drivers in the EM framework
are not required to match real performance states of the target. This
is particularly important on targets where the performance states are
not known by the OS.
The power cost coefficients managed by the EM framework are specified in
milli-watts. Although the two potential users of those coefficients (IPA
and EAS) only need relative correctness, IPA specifically needs to
compare the power of CPUs with the power of other components (GPUs, for
example), which are still expressed in absolute terms in their
respective subsystems. Hence, specifying the power of CPUs in
milli-watts should help transitioning IPA to using the EM framework
without introducing new problems by keeping units comparable across
sub-systems.
On the longer term, the EM of other devices than CPUs could also be
managed by the EM framework, which would enable to remove the absolute
unit. However, this is not absolutely required as a first step, so this
extension of the EM framework is left for later.
On the client side, the EM framework offers APIs to access the power
cost tables of a CPU (em_cpu_get()), and to estimate the energy
consumed by the CPUs of a performance domain (em_pd_energy()). Clients
such as the task scheduler can then use these APIs to access the shared
data structures holding the Energy Model of CPUs.
Signed-off-by: Quentin Perret <quentin.perret@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: adharmap@codeaurora.org
Cc: chris.redpath@arm.com
Cc: currojerez@riseup.net
Cc: dietmar.eggemann@arm.com
Cc: edubezval@gmail.com
Cc: gregkh@linuxfoundation.org
Cc: javi.merino@kernel.org
Cc: joel@joelfernandes.org
Cc: juri.lelli@redhat.com
Cc: morten.rasmussen@arm.com
Cc: patrick.bellasi@arm.com
Cc: pkondeti@codeaurora.org
Cc: skannan@codeaurora.org
Cc: smuckle@google.com
Cc: srinivas.pandruvada@linux.intel.com
Cc: thara.gopinath@linaro.org
Cc: tkjos@google.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Cc: viresh.kumar@linaro.org
Link: https://lkml.kernel.org/r/20181203095628.11858-4-quentin.perret@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
316 lines
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316 lines
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Plaintext
config SUSPEND
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bool "Suspend to RAM and standby"
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depends on ARCH_SUSPEND_POSSIBLE
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default y
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---help---
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Allow the system to enter sleep states in which main memory is
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powered and thus its contents are preserved, such as the
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suspend-to-RAM state (e.g. the ACPI S3 state).
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config SUSPEND_FREEZER
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bool "Enable freezer for suspend to RAM/standby" \
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if ARCH_WANTS_FREEZER_CONTROL || BROKEN
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depends on SUSPEND
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default y
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help
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This allows you to turn off the freezer for suspend. If this is
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done, no tasks are frozen for suspend to RAM/standby.
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Turning OFF this setting is NOT recommended! If in doubt, say Y.
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config SUSPEND_SKIP_SYNC
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bool "Skip kernel's sys_sync() on suspend to RAM/standby"
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depends on SUSPEND
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depends on EXPERT
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help
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Skip the kernel sys_sync() before freezing user processes.
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Some systems prefer not to pay this cost on every invocation
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of suspend, or they are content with invoking sync() from
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user-space before invoking suspend. Say Y if that's your case.
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config HIBERNATE_CALLBACKS
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bool
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config HIBERNATION
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bool "Hibernation (aka 'suspend to disk')"
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depends on SWAP && ARCH_HIBERNATION_POSSIBLE
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select HIBERNATE_CALLBACKS
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select LZO_COMPRESS
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select LZO_DECOMPRESS
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select CRC32
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---help---
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Enable the suspend to disk (STD) functionality, which is usually
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called "hibernation" in user interfaces. STD checkpoints the
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system and powers it off; and restores that checkpoint on reboot.
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You can suspend your machine with 'echo disk > /sys/power/state'
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after placing resume=/dev/swappartition on the kernel command line
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in your bootloader's configuration file.
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Alternatively, you can use the additional userland tools available
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from <http://suspend.sf.net>.
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In principle it does not require ACPI or APM, although for example
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ACPI will be used for the final steps when it is available. One
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of the reasons to use software suspend is that the firmware hooks
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for suspend states like suspend-to-RAM (STR) often don't work very
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well with Linux.
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It creates an image which is saved in your active swap. Upon the next
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boot, pass the 'resume=/dev/swappartition' argument to the kernel to
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have it detect the saved image, restore memory state from it, and
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continue to run as before. If you do not want the previous state to
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be reloaded, then use the 'noresume' kernel command line argument.
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Note, however, that fsck will be run on your filesystems and you will
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need to run mkswap against the swap partition used for the suspend.
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It also works with swap files to a limited extent (for details see
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<file:Documentation/power/swsusp-and-swap-files.txt>).
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Right now you may boot without resuming and resume later but in the
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meantime you cannot use the swap partition(s)/file(s) involved in
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suspending. Also in this case you must not use the filesystems
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that were mounted before the suspend. In particular, you MUST NOT
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MOUNT any journaled filesystems mounted before the suspend or they
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will get corrupted in a nasty way.
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For more information take a look at <file:Documentation/power/swsusp.txt>.
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config ARCH_SAVE_PAGE_KEYS
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bool
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config PM_STD_PARTITION
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string "Default resume partition"
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depends on HIBERNATION
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default ""
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---help---
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The default resume partition is the partition that the suspend-
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to-disk implementation will look for a suspended disk image.
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The partition specified here will be different for almost every user.
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It should be a valid swap partition (at least for now) that is turned
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on before suspending.
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The partition specified can be overridden by specifying:
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resume=/dev/<other device>
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which will set the resume partition to the device specified.
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Note there is currently not a way to specify which device to save the
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suspended image to. It will simply pick the first available swap
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device.
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config PM_SLEEP
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def_bool y
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depends on SUSPEND || HIBERNATE_CALLBACKS
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select PM
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select SRCU
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config PM_SLEEP_SMP
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def_bool y
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depends on SMP
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depends on ARCH_SUSPEND_POSSIBLE || ARCH_HIBERNATION_POSSIBLE
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depends on PM_SLEEP
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select HOTPLUG_CPU
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config PM_AUTOSLEEP
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bool "Opportunistic sleep"
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depends on PM_SLEEP
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default n
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---help---
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Allow the kernel to trigger a system transition into a global sleep
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state automatically whenever there are no active wakeup sources.
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config PM_WAKELOCKS
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bool "User space wakeup sources interface"
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depends on PM_SLEEP
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default n
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---help---
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Allow user space to create, activate and deactivate wakeup source
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objects with the help of a sysfs-based interface.
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config PM_WAKELOCKS_LIMIT
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int "Maximum number of user space wakeup sources (0 = no limit)"
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range 0 100000
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default 100
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depends on PM_WAKELOCKS
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config PM_WAKELOCKS_GC
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bool "Garbage collector for user space wakeup sources"
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depends on PM_WAKELOCKS
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default y
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config PM
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bool "Device power management core functionality"
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---help---
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Enable functionality allowing I/O devices to be put into energy-saving
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(low power) states, for example after a specified period of inactivity
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(autosuspended), and woken up in response to a hardware-generated
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wake-up event or a driver's request.
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Hardware support is generally required for this functionality to work
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and the bus type drivers of the buses the devices are on are
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responsible for the actual handling of device suspend requests and
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wake-up events.
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config PM_DEBUG
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bool "Power Management Debug Support"
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depends on PM
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---help---
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This option enables various debugging support in the Power Management
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code. This is helpful when debugging and reporting PM bugs, like
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suspend support.
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config PM_ADVANCED_DEBUG
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bool "Extra PM attributes in sysfs for low-level debugging/testing"
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depends on PM_DEBUG
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---help---
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Add extra sysfs attributes allowing one to access some Power Management
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fields of device objects from user space. If you are not a kernel
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developer interested in debugging/testing Power Management, say "no".
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config PM_TEST_SUSPEND
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bool "Test suspend/resume and wakealarm during bootup"
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depends on SUSPEND && PM_DEBUG && RTC_CLASS=y
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---help---
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This option will let you suspend your machine during bootup, and
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make it wake up a few seconds later using an RTC wakeup alarm.
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Enable this with a kernel parameter like "test_suspend=mem".
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You probably want to have your system's RTC driver statically
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linked, ensuring that it's available when this test runs.
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config PM_SLEEP_DEBUG
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def_bool y
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depends on PM_DEBUG && PM_SLEEP
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config DPM_WATCHDOG
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bool "Device suspend/resume watchdog"
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depends on PM_DEBUG && PSTORE && EXPERT
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---help---
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Sets up a watchdog timer to capture drivers that are
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locked up attempting to suspend/resume a device.
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A detected lockup causes system panic with message
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captured in pstore device for inspection in subsequent
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boot session.
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config DPM_WATCHDOG_TIMEOUT
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int "Watchdog timeout in seconds"
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range 1 120
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default 120
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depends on DPM_WATCHDOG
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config PM_TRACE
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bool
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help
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This enables code to save the last PM event point across
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reboot. The architecture needs to support this, x86 for
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example does by saving things in the RTC, see below.
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The architecture specific code must provide the extern
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functions from <linux/resume-trace.h> as well as the
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<asm/resume-trace.h> header with a TRACE_RESUME() macro.
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The way the information is presented is architecture-
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dependent, x86 will print the information during a
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late_initcall.
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config PM_TRACE_RTC
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bool "Suspend/resume event tracing"
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depends on PM_SLEEP_DEBUG
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depends on X86
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select PM_TRACE
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---help---
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This enables some cheesy code to save the last PM event point in the
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RTC across reboots, so that you can debug a machine that just hangs
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during suspend (or more commonly, during resume).
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To use this debugging feature you should attempt to suspend the
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machine, reboot it and then run
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dmesg -s 1000000 | grep 'hash matches'
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CAUTION: this option will cause your machine's real-time clock to be
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set to an invalid time after a resume.
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config APM_EMULATION
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tristate "Advanced Power Management Emulation"
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depends on SYS_SUPPORTS_APM_EMULATION
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help
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APM is a BIOS specification for saving power using several different
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techniques. This is mostly useful for battery powered laptops with
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APM compliant BIOSes. If you say Y here, the system time will be
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reset after a RESUME operation, the /proc/apm device will provide
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battery status information, and user-space programs will receive
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notification of APM "events" (e.g. battery status change).
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In order to use APM, you will need supporting software. For location
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and more information, read <file:Documentation/power/apm-acpi.txt>
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and the Battery Powered Linux mini-HOWTO, available from
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<http://www.tldp.org/docs.html#howto>.
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This driver does not spin down disk drives (see the hdparm(8)
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manpage ("man 8 hdparm") for that), and it doesn't turn off
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VESA-compliant "green" monitors.
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Generally, if you don't have a battery in your machine, there isn't
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much point in using this driver and you should say N. If you get
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random kernel OOPSes or reboots that don't seem to be related to
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anything, try disabling/enabling this option (or disabling/enabling
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APM in your BIOS).
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config PM_CLK
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def_bool y
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depends on PM && HAVE_CLK
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config PM_GENERIC_DOMAINS
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bool
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depends on PM
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config WQ_POWER_EFFICIENT_DEFAULT
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bool "Enable workqueue power-efficient mode by default"
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depends on PM
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default n
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help
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Per-cpu workqueues are generally preferred because they show
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better performance thanks to cache locality; unfortunately,
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per-cpu workqueues tend to be more power hungry than unbound
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workqueues.
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Enabling workqueue.power_efficient kernel parameter makes the
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per-cpu workqueues which were observed to contribute
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significantly to power consumption unbound, leading to measurably
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lower power usage at the cost of small performance overhead.
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This config option determines whether workqueue.power_efficient
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is enabled by default.
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If in doubt, say N.
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config PM_GENERIC_DOMAINS_SLEEP
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def_bool y
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depends on PM_SLEEP && PM_GENERIC_DOMAINS
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config PM_GENERIC_DOMAINS_OF
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def_bool y
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depends on PM_GENERIC_DOMAINS && OF
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config CPU_PM
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bool
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config ENERGY_MODEL
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bool "Energy Model for CPUs"
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depends on SMP
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depends on CPU_FREQ
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default n
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help
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Several subsystems (thermal and/or the task scheduler for example)
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can leverage information about the energy consumed by CPUs to make
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smarter decisions. This config option enables the framework from
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which subsystems can access the energy models.
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The exact usage of the energy model is subsystem-dependent.
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If in doubt, say N.
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