Commit Graph

58 Commits

Author SHA1 Message Date
Rafael J. Wysocki
f3db6de55e Merge branch 'pm-cpufreq'
* pm-cpufreq:
  cpufreq: intel_pstate: Implement passive mode with HWP enabled
2020-08-14 19:39:35 +02:00
Rafael J. Wysocki
f6ebbcf08f cpufreq: intel_pstate: Implement passive mode with HWP enabled
Allow intel_pstate to work in the passive mode with HWP enabled and
make it set the HWP minimum performance limit (HWP floor) to the
P-state value given by the target frequency supplied by the cpufreq
governor, so as to prevent the HWP algorithm and the CPU scheduler
from working against each other, at least when the schedutil governor
is in use, and update the intel_pstate documentation accordingly.

Among other things, this allows utilization clamps to be taken
into account, at least to a certain extent, when intel_pstate is
in use and makes it more likely that sufficient capacity for
deadline tasks will be provided.

After this change, the resulting behavior of an HWP system with
intel_pstate in the passive mode should be close to the behavior
of the analogous non-HWP system with intel_pstate in the passive
mode, except that the HWP algorithm is generally allowed to make the
CPU run at a frequency above the floor P-state set by intel_pstate in
the entire available range of P-states, while without HWP a CPU can
run in a P-state above the requested one if the latter falls into the
range of turbo P-states (referred to as the turbo range) or if the
P-states of all CPUs in one package are coordinated with each other
at the hardware level.

[Note that in principle the HWP floor may not be taken into account
 by the processor if it falls into the turbo range, in which case the
 processor has a license to choose any P-state, either below or above
 the HWP floor, just like a non-HWP processor in the case when the
 target P-state falls into the turbo range.]

With this change applied, intel_pstate in the passive mode assumes
complete control over the HWP request MSR and concurrent changes of
that MSR (eg. via the direct MSR access interface) are overridden by
it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
2020-08-11 17:29:45 +02:00
Linus Torvalds
2324d50d05 It's been a busy cycle for documentation - hopefully the busiest for a
while to come.  Changes include:
 
  - Some new Chinese translations
 
  - Progress on the battle against double words words and non-HTTPS URLs
 
  - Some block-mq documentation
 
  - More RST conversions from Mauro.  At this point, that task is
    essentially complete, so we shouldn't see this kind of churn again for a
    while.  Unless we decide to switch to asciidoc or something...:)
 
  - Lots of typo fixes, warning fixes, and more.
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Merge tag 'docs-5.9' of git://git.lwn.net/linux

Pull documentation updates from Jonathan Corbet:
 "It's been a busy cycle for documentation - hopefully the busiest for a
  while to come. Changes include:

   - Some new Chinese translations

   - Progress on the battle against double words words and non-HTTPS
     URLs

   - Some block-mq documentation

   - More RST conversions from Mauro. At this point, that task is
     essentially complete, so we shouldn't see this kind of churn again
     for a while. Unless we decide to switch to asciidoc or
     something...:)

   - Lots of typo fixes, warning fixes, and more"

* tag 'docs-5.9' of git://git.lwn.net/linux: (195 commits)
  scripts/kernel-doc: optionally treat warnings as errors
  docs: ia64: correct typo
  mailmap: add entry for <alobakin@marvell.com>
  doc/zh_CN: add cpu-load Chinese version
  Documentation/admin-guide: tainted-kernels: fix spelling mistake
  MAINTAINERS: adjust kprobes.rst entry to new location
  devices.txt: document rfkill allocation
  PCI: correct flag name
  docs: filesystems: vfs: correct flag name
  docs: filesystems: vfs: correct sync_mode flag names
  docs: path-lookup: markup fixes for emphasis
  docs: path-lookup: more markup fixes
  docs: path-lookup: fix HTML entity mojibake
  CREDITS: Replace HTTP links with HTTPS ones
  docs: process: Add an example for creating a fixes tag
  doc/zh_CN: add Chinese translation prefer section
  doc/zh_CN: add clearing-warn-once Chinese version
  doc/zh_CN: add admin-guide index
  doc:it_IT: process: coding-style.rst: Correct __maybe_unused compiler label
  futex: MAINTAINERS: Re-add selftests directory
  ...
2020-08-04 22:47:54 -07:00
Randy Dunlap
b45225b41a Documentation/admin-guide: intel-speed-select: drop doubled words
Drop the doubled words "that" and "and".

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: platform-driver-x86@vger.kernel.org
Link: https://lore.kernel.org/r/20200704032020.21923-11-rdunlap@infradead.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-07-05 14:01:49 -06:00
Randy Dunlap
4d7e204f7d Documentation/admin-guide: intel_pstate: drop doubled word
Drop the doubled word "to".

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Cc: Len Brown <lenb@kernel.org>
Cc: linux-pm@vger.kernel.org
Link: https://lore.kernel.org/r/20200704032020.21923-10-rdunlap@infradead.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2020-07-05 14:01:49 -06:00
Quentin Perret
8412b4563e cpufreq: Specify default governor on command line
Currently, the only way to specify the default CPUfreq governor is
via Kconfig options, which suits users who can build the kernel
themselves perfectly.

However, for those who use a distro-like kernel (such as Android,
with the Generic Kernel Image project), the only way to use a
non-default governor is to boot to userspace, and to then switch
using the sysfs interface. Being able to specify the default governor
on the command line, like is the case for cpuidle, would allow those
users to specify their governor of choice earlier on, and to simplify
the userspace boot procedure slighlty.

To support this use-case, add a kernel command line parameter
allowing the default governor for CPUfreq to be specified, which
takes precedence over the built-in default.

This implementation has one notable limitation: the default governor
must be registered before the driver. This is solved for builtin
governors and drivers using appropriate *_initcall() functions. And
in the modular case, this must be reflected as a constraint on the
module loading order.

Signed-off-by: Quentin Perret <qperret@google.com>
[ Viresh: Converted 'default_governor' to a string and parsing it only
	  at initcall level, and several updates to
	  cpufreq_init_policy(). ]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2020-07-02 13:03:30 +02:00
Srinivas Pandruvada
f473bf398b cpufreq: intel_pstate: Allow raw energy performance preference value
Currently using attribute "energy_performance_preference", user space can
write one of the four per-defined preference string. These preference
strings gets mapped to a hard-coded Energy-Performance Preference (EPP) or
Energy-Performance Bias (EPB) knob.

These four values are supposed to cover broad spectrum of use cases, but
are not uniformly distributed in the range. There are number of cases,
where this is not enough. For example:

Suppose user wants more performance when connected to AC. Instead of using
default "balance performance", the "performance" setting can be used. This
changes EPP value from 0x80 to 0x00. But setting EPP to 0, results in
electrical and thermal issues on some platforms. This results in
aggressive throttling, which causes a drop in performance. But some value
between 0x80 and 0x00 results in better performance. But that value can't
be fixed as the power curve is not linear. In some cases just changing EPP
from 0x80 to 0x75 is enough to get significant performance gain.

Similarly on battery the default "balance_performance" mode can be
aggressive in power consumption. But picking up the next choice
"balance power" results in too much loss of performance, which results in
bad user experience in use cases like "Google Hangout". It was observed
that some value between these two EPP is optimal.

This change allows fine grain EPP tuning for platform like Chromebook or
for users who wants to fine tune power and performance.
Here based on the product and use cases, different EPP values can be set.
This change is similar to the change done for:
/sys/devices/system/cpu/cpu*/power/energy_perf_bias
where user has choice to write a predefined string or raw value.

The change itself is trivial. When user preference doesn't match
predefined string preferences and value is an unsigned integer and in
range, use that value for EPP. When the EPP feature is not present
writing raw value is not supported.

Suggested-by: Len Brown <lenb@kernel.org>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2020-07-02 13:02:46 +02:00
Srinivas Pandruvada
ed7bde7a6d cpufreq: intel_pstate: Allow enable/disable energy efficiency
By default intel_pstate the driver disables energy efficiency by setting
MSR_IA32_POWER_CTL bit 19 for Kaby Lake desktop CPU model in HWP mode.
This CPU model is also shared by Coffee Lake desktop CPUs. This allows
these systems to reach maximum possible frequency. But this adds power
penalty, which some customers don't want. They want some way to enable/
disable dynamically.

So, add an additional attribute "energy_efficiency" under
/sys/devices/system/cpu/intel_pstate/ for these CPU models. This allows
to read and write bit 19 ("Disable Energy Efficiency Optimization") in
the MSR IA32_POWER_CTL.

This attribute is present in both HWP and non-HWP mode as this has an
effect in both modes. Refer to Intel Software Developer's manual for
details.

The scope of this bit is package wide. Also these systems are single
package systems. So read/write MSR on the current CPU is enough.

The energy efficiency (EE) bit setting needs to be preserved during
suspend/resume and CPU offline/online operation. To do this:
- Restoring the EE setting from the cpufreq resume() callback, if there
is change from the system default.
- By default, don't disable EE from cpufreq init() callback for matching
CPU models. Since the scope is package wide and is a single package
system, move the disable EE calls from init() callback to
intel_pstate_init() function, which is called only once.

Suggested-by: Len Brown <lenb@kernel.org>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2020-07-02 13:02:46 +02:00
Rafael J. Wysocki
a34024d98e Merge branches 'pm-devfreq', 'powercap', 'pm-docs' and 'pm-tools'
* pm-devfreq:
  PM / devfreq: Use lockdep asserts instead of manual checks for locked mutex
  PM / devfreq: imx-bus: Fix inconsistent IS_ERR and PTR_ERR
  PM / devfreq: Replace strncpy with strscpy
  PM / devfreq: imx: Register interconnect device
  PM / devfreq: Add generic imx bus scaling driver
  PM / devfreq: tegra30: Delete an error message in tegra_devfreq_probe()
  PM / devfreq: tegra30: Make CPUFreq notifier to take into account boosting

* powercap:
  powercap: RAPL: remove unused local MSR define
  powercap/intel_rapl: add support for ElkhartLake

* pm-docs:
  Documentation: admin-guide: pm: Document intel-speed-select

* pm-tools:
  cpupower: Remove unneeded semicolon
2020-06-01 15:20:45 +02:00
Rafael J. Wysocki
ac7ccfc75f Merge branch 'pm-cpufreq'
* pm-cpufreq:
  cpufreq: Fix up cpufreq_boost_set_sw()
  cpufreq: fix minor typo in struct cpufreq_driver doc comment
  cpufreq: qoriq: Add platform dependencies
  clk: qoriq: add cpufreq platform device
  cpufreq: qoriq: convert to a platform driver
  cpufreq: qcom: fix wrong compatible binding
  cpufreq: imx-cpufreq-dt: support i.MX7ULP
  cpufreq: dt: Add support for r8a7742
  cpufreq: Add i.MX7ULP to cpufreq-dt-platdev blacklist
  cpufreq: omap: Build driver by default for ARCH_OMAP2PLUS
  cpufreq: intel_pstate: Use passive mode by default without HWP
2020-06-01 15:19:39 +02:00
Srinivas Pandruvada
213081dadd Documentation: admin-guide: pm: Document intel-speed-select
Added documentation to configure servers to use Intel(R) Speed
Select Technology using intel-speed-select tool.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Acked-by: Andriy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2020-05-19 19:59:10 +02:00
Hanjun Guo
7395683a24 Documentation: cpuidle: update the document
Update the document after the remove of cpuidle_sysfs_switch.

Signed-off-by: Hanjun Guo <guohanjun@huawei.com>
Reviewed-by: Doug Smythies <dsmythies@telus.net>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2020-05-19 17:41:17 +02:00
Rafael J. Wysocki
33aa46f252 cpufreq: intel_pstate: Use passive mode by default without HWP
After recent changes allowing scale-invariant utilization to be
used on x86, the schedutil governor on top of intel_pstate in the
passive mode should be on par with (or better than) the active mode
"powersave" algorithm of intel_pstate on systems in which
hardware-managed P-states (HWP) are not used, so it should not be
necessary to use the internal scaling algorithm in those cases.

Accordingly, modify intel_pstate to start in the passive mode by
default if the processor at hand does not support HWP of if the driver
is requested to avoid using HWP through the kernel command line.

Among other things, that will allow utilization clamps and the
support for RT/DL tasks in the schedutil governor to be utilized on
systems in which intel_pstate is used.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2020-04-17 17:04:38 +02:00
Rafael J. Wysocki
4506c531f1 Documentation: PM: sleep: Document system-wide suspend code flows
Add a document describing high-level system-wide suspend code flows
in Linux.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2020-04-03 11:41:01 +02:00
Rafael J. Wysocki
2409000a0c Merge branches 'pm-devfreq', 'powercap' and 'pm-docs'
* pm-devfreq:
  PM / devfreq: Get rid of some doc warnings
  PM / devfreq: Fix handling dev_pm_qos_remove_request result
  PM / devfreq: Fix a typo in a comment
  PM / devfreq: Change to DEVFREQ_GOV_UPDATE_INTERVAL event name
  PM / devfreq: Remove unneeded extern keyword
  PM / devfreq: Use constant name of userspace governor

* powercap:
  powercap: idle_inject: Replace zero-length array with flexible-array member

* pm-docs:
  docs: cpu-freq: convert cpufreq-stats.txt to ReST
  docs: cpu-freq: convert cpu-drivers.txt to ReST
  docs: cpu-freq: convert core.txt to ReST
  docs: cpu-freq: convert index.txt to ReST
  docs: cpufreq: fix a broken reference
  Documentation: cpufreq: Move legacy driver documentation
2020-03-30 14:48:31 +02:00
Rafael J. Wysocki
0411f0d10e Merge branch 'pm-cpufreq'
* pm-cpufreq:
  cpufreq: intel_pstate: Simplify intel_pstate_cpu_init()
  cpufreq: qcom: Add support for krait based socs
  cpufreq: imx6q-cpufreq: Improve the logic of -EPROBE_DEFER handling
  cpufreq: Use scnprintf() for avoiding potential buffer overflow
  Documentation: intel_pstate: update links for references
  cpufreq: intel_pstate: Consolidate policy verification
  cpufreq: dt: Allow platform specific intermediate callbacks
  cpufreq: imx-cpufreq-dt: Correct i.MX8MP's market segment fuse location
  cpufreq: imx6q: read OCOTP through nvmem for imx6q
  cpufreq: imx6q: fix error handling
  cpufreq: imx-cpufreq-dt: Add "cpu-supply" property check
  cpufreq: ti-cpufreq: Add support for OPP_PLUS
  cpufreq: imx6q: Fixes unwanted cpu overclocking on i.MX6ULL
2020-03-30 14:46:27 +02:00
Alex Hung
c1f59a3782 Documentation: intel_pstate: update links for references
URLs for presentation and Intel Software Developer’s Manual are updated
as they were using "http" which are gradually replaced by "https".

Signed-off-by: Alex Hung <alex.hung@canonical.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2020-03-14 11:46:02 +01:00
Rafael J. Wysocki
03b2249650 Documentation: cpufreq: Move legacy driver documentation
There are three legacy driver documents in Documentation/cpu-freq/
that were added years ago and converting them each to the .rst
format is rather pointless, even though there is some value in
preserving them.  However, if they are preserved, they need to go
into the admin-guide part of cpufreq documentation where they belong
(at least to a certain extent).

To preserve them with minimum amount of changes and put them into the
right place, and make it possible to process them into HTML (and other
formats) along with the rest of the documentation, move them each
as a "literal text" block into a separate section of a single .rst
"wrapper" file under Documentation/admin-guide/pm/.

While at it, repair the PCC specification URL in one of them.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2020-03-02 11:31:06 +01:00
Rafael J. Wysocki
b8e6e27c62 Documentation: PM: QoS: Update to reflect previous code changes
Update the PM QoS documentation to reflect the previous code changes
regarding the removal of PM QoS classes and the CPU latency QoS API
rework.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
Tested-by: Amit Kucheria <amit.kucheria@linaro.org>
2020-02-14 10:37:26 +01:00
Rafael J. Wysocki
332008256f Merge branches 'pm-avs' and 'pm-cpuidle'
* pm-avs:
  power: avs: qcom-cpr: Avoid clang -Wsometimes-uninitialized in cpr_scale
  power: avs: qcom-cpr: add unspecified HAS_IOMEM dependency
  PM / AVS: rockchip-io: fix the supply naming for the emmc supply on px30
  power: avs: qcom-cpr: add a printout after the driver has been initialized

* pm-cpuidle:
  cpuidle: Documentation: Clean up PM QoS description
  intel_idle: Introduce 'states_off' module parameter
  intel_idle: Introduce 'use_acpi' module parameter
2020-02-07 11:01:40 +01:00
Rafael J. Wysocki
f06572ef47 cpuidle: Documentation: Clean up PM QoS description
Clean up the language in one paragraph in the PM QoS description in
Documentation/admin-guide/pm/cpuidle.rst.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2020-02-05 02:08:31 +01:00
Rafael J. Wysocki
c21502efda Documentation: admin-guide: PM: Update sleep states documentation
There is some information in Documentation/power/interface.rst that
is still missing from Documentation/admin-guide/pm/sleep-states.rst
and really should be present in there, so update the latter by
adding that information to it and delete the former (as it becomes
redundant after that and it is somewhat outdated).

While at it, clean up some assorted pieces of sleep-states.rst a bit.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2020-02-03 11:58:26 +01:00
Rafael J. Wysocki
4dcb78ee57 intel_idle: Introduce 'states_off' module parameter
In certain system configurations it may not be desirable to use some
C-states assumed to be available by intel_idle and the driver needs
to be prevented from using them even before the cpuidle sysfs
interface becomes accessible to user space.  Currently, the only way
to achieve that is by setting the 'max_cstate' module parameter to a
value lower than the index of the shallowest of the C-states in
question, but that may be overly intrusive, because it effectively
makes all of the idle states deeper than the 'max_cstate' one go
away (and the C-state to avoid may be in the middle of the range
normally regarded as available).

To allow that limitation to be overcome, introduce a new module
parameter called 'states_off' to represent a list of idle states to
be disabled by default in the form of a bitmask and update the
documentation to cover it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2020-02-03 11:57:18 +01:00
Rafael J. Wysocki
3a5be9b8f4 intel_idle: Introduce 'use_acpi' module parameter
For diagnostics, it is generally useful to be able to make intel_idle
take the system's ACPI tables into consideration even if that is not
required for the processor model in there, so introduce a new module
parameter, 'use_acpi', to make that happen and update the documentation
to cover it.

While at it, fix the 'no_acpi' module parameter name in the
documentation.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2020-02-03 11:57:08 +01:00
Rafael J. Wysocki
a329918221 Documentation: admin-guide: PM: Add intel_idle document
Add an admin-guide document for the intel_idle driver to describe
how it works: how it enumerates idle states, what happens during the
initialization of it, how it can be controlled via the kernel command
line and so on.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
2020-01-15 10:54:58 +01:00
Rafael J. Wysocki
75a8026741 cpuidle: Allow idle states to be disabled by default
In certain situations it may be useful to prevent some idle states
from being used by default while allowing user space to enable them
later on.

For this purpose, introduce a new state flag, CPUIDLE_FLAG_OFF, to
mark idle states that should be disabled by default, make the core
set CPUIDLE_STATE_DISABLED_BY_USER for those states at the
initialization time and add a new state attribute in sysfs,
"default_status", to inform user space of the initial status of
the given idle state ("disabled" if CPUIDLE_FLAG_OFF is set for it,
"enabled" otherwise).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2019-12-27 11:02:08 +01:00
Rafael J. Wysocki
7afc53951a Merge branches 'pm-docs' and 'pm-misc'
* pm-docs:
  Documentation: PM: Unify copyright notices
  Documentation: PM: Add SPDX license tags to multiple files
  cpufreq: intel_pstate: Documentation: Add references sections

* pm-misc:
  firmware/psci: add support for SYSTEM_RESET2
  drivers: firmware: psci: Announce support for OS initiated suspend mode
  drivers: firmware: psci: Simplify error path of psci_dt_init()
  drivers: firmware: psci: Split psci_dt_cpu_init_idle()
  MAINTAINERS: Update files for PSCI
  drivers: firmware: psci: Move psci to separate directory
2019-05-06 10:55:19 +02:00
Rafael J. Wysocki
7973b799db admin-guide: pm: intel_epb: Add SPDX license tag and copyright notice
Add an SPDX license tag and a copyright notice to the intel_epb.rst
file under Documentation/admin-quide/pm.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2019-04-08 12:59:09 +02:00
Rafael J. Wysocki
fc1860d6b1 Documentation: PM: Unify copyright notices
Unify copyright notices in the .rst files under
Documentation/driver-api/pm and Documentation/admin-quide/pm.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2019-04-08 12:57:47 +02:00
Rafael J. Wysocki
fc7db767b1 Documentation: PM: Add SPDX license tags to multiple files
Add SPDX license tags to .rst files under Documentation/driver-api/pm
and Documentation/admin-quide/pm.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2019-04-08 12:57:47 +02:00
Rafael J. Wysocki
1120b0f985 cpufreq: intel_pstate: Documentation: Add references sections
Add separate refereces sections to the cpufreq.rst and
intel_pstate.rst documents under admin-quide/pm and list the
references to external documentation in there.

Update the ACPI specification URL while at it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2019-04-08 12:57:47 +02:00
Rafael J. Wysocki
b9c273babc PM / arch: x86: MSR_IA32_ENERGY_PERF_BIAS sysfs interface
The Performance and Energy Bias Hint (EPB) is expected to be set by
user space through the generic MSR interface, but that interface is
not particularly nice and there are security concerns regarding it,
so it is not always available.

For this reason, add a sysfs interface for reading and updating the
EPB, in the form of a new attribute, energy_perf_bias, located
under /sys/devices/system/cpu/cpu#/power/ for online CPUs that
support the EPB feature.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Acked-by: Borislav Petkov <bp@suse.de>
2019-04-07 22:33:42 +02:00
Rafael J. Wysocki
5861381d48 PM / arch: x86: Rework the MSR_IA32_ENERGY_PERF_BIAS handling
The current handling of MSR_IA32_ENERGY_PERF_BIAS in the kernel is
problematic, because it may cause changes made by user space to that
MSR (with the help of the x86_energy_perf_policy tool, for example)
to be lost every time a CPU goes offline and then back online as well
as during system-wide power management transitions into sleep states
and back into the working state.

The first problem is that if the current EPB value for a CPU going
online is 0 ('performance'), the kernel will change it to 6 ('normal')
regardless of whether or not this is the first bring-up of that CPU.
That also happens during system-wide resume from sleep states
(including, but not limited to, hibernation).  However, the EPB may
have been adjusted by user space this way and the kernel should not
blindly override that setting.

The second problem is that if the platform firmware resets the EPB
values for any CPUs during system-wide resume from a sleep state,
the kernel will not restore their previous EPB values that may
have been set by user space before the preceding system-wide
suspend transition.  Again, that behavior may at least be confusing
from the user space perspective.

In order to address these issues, rework the handling of
MSR_IA32_ENERGY_PERF_BIAS so that the EPB value is saved on CPU
offline and restored on CPU online as well as (for the boot CPU)
during the syscore stages of system-wide suspend and resume
transitions, respectively.

However, retain the policy by which the EPB is set to 6 ('normal')
on the first bring-up of each CPU if its initial value is 0, based
on the observation that 0 may mean 'not initialized' just as well as
'performance' in that case.

While at it, move the MSR_IA32_ENERGY_PERF_BIAS handling code into
a separate file and document it in Documentation/admin-guide.

Fixes: abe48b1082 (x86, intel, power: Initialize MSR_IA32_ENERGY_PERF_BIAS)
Fixes: b51ef52df7 (x86/cpu: Restore MSR_IA32_ENERGY_PERF_BIAS after resume)
Reported-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Acked-by: Borislav Petkov <bp@suse.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
2019-04-07 22:33:19 +02:00
Rafael J. Wysocki
b26bf6ab71 cpuidle: New timer events oriented governor for tickless systems
The venerable menu governor does some things that are quite
questionable in my view.

First, it includes timer wakeups in the pattern detection data and
mixes them up with wakeups from other sources which in some cases
causes it to expect what essentially would be a timer wakeup in a
time frame in which no timer wakeups are possible (because it knows
the time until the next timer event and that is later than the
expected wakeup time).

Second, it uses the extra exit latency limit based on the predicted
idle duration and depending on the number of tasks waiting on I/O,
even though those tasks may run on a different CPU when they are
woken up.  Moreover, the time ranges used by it for the sleep length
correction factors depend on whether or not there are tasks waiting
on I/O, which again doesn't imply anything in particular, and they
are not correlated to the list of available idle states in any way
whatever.

Also, the pattern detection code in menu may end up considering
values that are too large to matter at all, in which cases running
it is a waste of time.

A major rework of the menu governor would be required to address
these issues and the performance of at least some workloads (tuned
specifically to the current behavior of the menu governor) is likely
to suffer from that.  It is thus better to introduce an entirely new
governor without them and let everybody use the governor that works
better with their actual workloads.

The new governor introduced here, the timer events oriented (TEO)
governor, uses the same basic strategy as menu: it always tries to
find the deepest idle state that can be used in the given conditions.
However, it applies a different approach to that problem.

First, it doesn't use "correction factors" for the time till the
closest timer, but instead it tries to correlate the measured idle
duration values with the available idle states and use that
information to pick up the idle state that is most likely to "match"
the upcoming CPU idle interval.

Second, it doesn't take the number of "I/O waiters" into account at
all and the pattern detection code in it avoids taking timer wakeups
into account.  It also only uses idle duration values less than the
current time till the closest timer (with the tick excluded) for that
purpose.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
2019-01-16 23:07:30 +01:00
Rafael J. Wysocki
3a56fe685d Merge branches 'pm-cpuidle', 'pm-cpufreq' and 'pm-cpufreq-sched'
* pm-cpuidle:
  cpuidle: Add 'above' and 'below' idle state metrics
  cpuidle: big.LITTLE: fix refcount leak
  cpuidle: Add cpuidle.governor= command line parameter
  cpuidle: poll_state: Disregard disable idle states
  Documentation: admin-guide: PM: Add cpuidle document

* pm-cpufreq:
  cpufreq: qcom-hw: Add support for QCOM cpufreq HW driver
  dt-bindings: cpufreq: Introduce QCOM cpufreq firmware bindings
  cpufreq: nforce2: Remove meaningless return
  cpufreq: ia64: Remove unused header files
  cpufreq: imx6q: save one condition block for normal case of nvmem read
  cpufreq: imx6q: remove unused code
  cpufreq: pmac64: add of_node_put()
  cpufreq: powernv: add of_node_put()
  Documentation: intel_pstate: Clarify coordination of P-State limits
  cpufreq: intel_pstate: Force HWP min perf before offline
  cpufreq: s3c24xx: Change to use DEFINE_SHOW_ATTRIBUTE macro

* pm-cpufreq-sched:
  sched/cpufreq: Add the SPDX tags
2018-12-21 10:06:06 +01:00
Rafael J. Wysocki
04dab58a39 cpuidle: Add 'above' and 'below' idle state metrics
Add two new metrics for CPU idle states, "above" and "below", to count
the number of times the given state had been asked for (or entered
from the kernel's perspective), but the observed idle duration turned
out to be too short or too long for it (respectively).

These metrics help to estimate the quality of the CPU idle governor
in use.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-12-12 23:22:18 +01:00
Rafael J. Wysocki
61cb5758d3 cpuidle: Add cpuidle.governor= command line parameter
Add cpuidle.governor= command line parameter to allow the default
cpuidle governor to be replaced.

That is useful, for example, if someone running a tickful kernel
wants to use the menu governor on it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-12-11 12:08:44 +01:00
Rafael J. Wysocki
aa5eee355b Documentation: admin-guide: PM: Add cpuidle document
Important information is missing from user/admin cpuidle documentation
available today, so add a new user/admin document for cpuidle containing
current and comprehensive information to admin-guide and drop the old
.txt documents it is replacing.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
2018-12-03 10:03:36 +01:00
Srinivas Pandruvada
60935c17e2 Documentation: intel_pstate: Clarify coordination of P-State limits
Explain influence of per-core P-states and hyper threading on the
effective performance.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-11-29 22:31:58 +01:00
Zhao Wei Liew
e531efa1e9 Documentation: cpufreq: Correct a typo
Fix a typo in the admin-guide documentation for cpufreq.

Signed-off-by: Zhao Wei Liew <zhaoweiliew@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-11-07 13:32:34 +01:00
Srinivas Pandruvada
4b73d334c5 Documentation: intel_pstate: Add base_frequency information
Updated documentation to explain base_frequency attribute.

Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-10-16 10:33:39 +02:00
Rafael J. Wysocki
649f53a3e4 Documentation: intel_pstate: Describe hwp_dynamic_boost sysfs knob
Document the recently introduced hwp_dynamic_boost sysfs knob
allowing user space to tell intel_pstate to use iowait boosting
in the active mode with HWP enabled (to improve performance).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
2018-06-27 13:02:06 +02:00
Rafael J. Wysocki
9e421b8fff Documentation: admin-guide: intel_pstate: Fix sysfs path
Fix an incorrect sysfs path in the intel_pstate admin-guide
documentation.

Fixes: 33fc30b470 (cpufreq: intel_pstate: Document the current behavior and user interface)
Reported-by: Pawit Pornkitprasan <p.pawit@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-06-27 13:02:06 +02:00
Rafael J. Wysocki
7a0f9d1eb5 Documentation: intel_pstate: Fix typo
Fix a typo in the intel_pstate admin-guide documentation.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-06-21 00:35:19 +02:00
Juri Lelli
13610c9348 PM: docs: intel_pstate: fix Active Mode w/o HWP paragraph
P-state selection algorithm (powersave or performance) is selected by
echoing the desired choice to scaling_governor sysfs attribute and not
to scaling_cur_freq (as currently stated).

Fix it.

Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-09 12:16:44 +02:00
Jonathan Neuschäfer
c72a0ded8d PM: docs: sleep-states: Fix a typo ("includig")
Fix a typo in admin-guide/pm/sleep-states.rst.

Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2018-05-09 12:15:13 +02:00
Rafael J. Wysocki
4afbce7b39 Merge branch 'pm-docs'
* pm-docs:
  PM: docs: Delete the obsolete states.txt document
  PM: docs: Describe high-level PM strategies and sleep states
2017-09-04 00:07:27 +02:00
Rafael J. Wysocki
ab271bc95b Merge branch 'intel_pstate'
* intel_pstate:
  cpufreq: intel_pstate: Shorten a couple of long names
  cpufreq: intel_pstate: Simplify intel_pstate_adjust_pstate()
  cpufreq: intel_pstate: Improve IO performance with per-core P-states
  cpufreq: intel_pstate: Drop INTEL_PSTATE_HWP_SAMPLING_INTERVAL
  cpufreq: intel_pstate: Drop ->update_util from pstate_funcs
  cpufreq: intel_pstate: Do not use PID-based P-state selection
2017-09-04 00:05:42 +02:00
Rafael J. Wysocki
bd87c8fb9d Merge branch 'pm-cpufreq'
* pm-cpufreq: (33 commits)
  cpufreq: imx6q: Fix imx6sx low frequency support
  cpufreq: speedstep-lib: make several arrays static, makes code smaller
  cpufreq: ti: Fix 'of_node_put' being called twice in error handling path
  cpufreq: dt-platdev: Drop few entries from whitelist
  cpufreq: dt-platdev: Automatically create cpufreq device with OPP v2
  ARM: ux500: don't select CPUFREQ_DT
  cpufreq: Convert to using %pOF instead of full_name
  cpufreq: Cap the default transition delay value to 10 ms
  cpufreq: dbx500: Delete obsolete driver
  mfd: db8500-prcmu: Get rid of cpufreq dependency
  cpufreq: enable the DT cpufreq driver on the Ux500
  cpufreq: Loongson2: constify platform_device_id
  cpufreq: dt: Add r8a7796 support to to use generic cpufreq driver
  cpufreq: remove setting of policy->cpu in policy->cpus during init
  cpufreq: mediatek: add support of cpufreq to MT7622 SoC
  cpufreq: mediatek: add cleanups with the more generic naming
  cpufreq: rcar: Add support for R8A7795 SoC
  cpufreq: dt: Add rk3328 compatible to use generic cpufreq driver
  cpufreq: s5pv210: add missing of_node_put()
  cpufreq: Allow dynamic switching with CPUFREQ_ETERNAL latency
  ...
2017-09-04 00:05:13 +02:00
Rafael J. Wysocki
0c0b6b7bc4 PM: docs: Describe high-level PM strategies and sleep states
Reorganize the power management part of admin-guide by adding a
description of major power management strategies supported by the
kernel (system-wide and working-state power management) to it and
dividing the rest of the material into the system-wide PM and
working-state PM chapters.

On top of that, add a description of system sleep states to the
system-wide PM chapter.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
2017-08-29 00:15:32 +02:00