<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-toradex.git/Documentation/admin-guide/pm, branch v6.15-rc5</title>
<subtitle>Linux kernel for Apalis and Colibri modules</subtitle>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/'/>
<entry>
<title>Merge tag 'pm-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm</title>
<updated>2025-03-25T22:00:18+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2025-03-25T22:00:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=7d20aa5c32ac8bd272b5470ddbd7ac6e0cb35714'/>
<id>7d20aa5c32ac8bd272b5470ddbd7ac6e0cb35714</id>
<content type='text'>
Pull power management updates from Rafael Wysocki:
 "These are dominated by cpufreq updates which in turn are dominated by
  updates related to boost support in the core and drivers and
  amd-pstate driver optimizations.

  Apart from the above, there are some cpuidle updates including a
  rework of the most recent idle intervals handling in the venerable
  menu governor that leads to significant improvements in some
  performance benchmarks, as the governor is now more likely to predict
  a shorter idle duration in some cases, and there are updates of the
  core device power management code, mostly related to system suspend
  and resume, that should help to avoid potential issues arising when
  the drivers of devices depending on one another want to use different
  optimizations.

  There is also a usual collection of assorted fixes and cleanups,
  including removal of some unused code.

  Specifics:

   - Manage sysfs attributes and boost frequencies efficiently from
     cpufreq core to reduce boilerplate code in drivers (Viresh Kumar)

   - Minor cleanups to cpufreq drivers (Aaron Kling, Benjamin Schneider,
     Dhananjay Ugwekar, Imran Shaik, zuoqian)

   - Migrate some cpufreq drivers to using for_each_present_cpu() (Jacky
     Bai)

   - cpufreq-qcom-hw DT binding fixes (Krzysztof Kozlowski)

   - Use str_enable_disable() helper in cpufreq_online() (Lifeng Zheng)

   - Optimize the amd-pstate driver to avoid cases where call paths end
     up calling the same writes multiple times and needlessly caching
     variables through code reorganization, locking overhaul and tracing
     adjustments (Mario Limonciello, Dhananjay Ugwekar)

   - Make it possible to avoid enabling capacity-aware scheduling (CAS)
     in the intel_pstate driver and relocate a check for out-of-band
     (OOB) platform handling in it to make it detect OOB before checking
     HWP availability (Rafael Wysocki)

   - Fix dbs_update() to avoid inadvertent conversions of negative
     integer values to unsigned int which causes CPU frequency selection
     to be inaccurate in some cases when the "conservative" cpufreq
     governor is in use (Jie Zhan)

   - Update the handling of the most recent idle intervals in the menu
     cpuidle governor to prevent useful information from being discarded
     by it in some cases and improve the prediction accuracy (Rafael
     Wysocki)

   - Make it possible to tell the intel_idle driver to ignore its
     built-in table of idle states for the given processor, clean up the
     handling of auto-demotion disabling on Baytrail and Cherrytrail
     chips in it, and update its MAINTAINERS entry (David Arcari, Artem
     Bityutskiy, Rafael Wysocki)

   - Make some cpuidle drivers use for_each_present_cpu() instead of
     for_each_possible_cpu() during initialization to avoid issues
     occurring when nosmp or maxcpus=0 are used (Jacky Bai)

   - Clean up the Energy Model handling code somewhat (Rafael Wysocki)

   - Use kfree_rcu() to simplify the handling of runtime Energy Model
     updates (Li RongQing)

   - Add an entry for the Energy Model framework to MAINTAINERS as
     properly maintained (Lukasz Luba)

   - Address RCU-related sparse warnings in the Energy Model code
     (Rafael Wysocki)

   - Remove ENERGY_MODEL dependency on SMP and allow it to be selected
     when DEVFREQ is set without CPUFREQ so it can be used on a wider
     range of systems (Jeson Gao)

   - Unify error handling during runtime suspend and runtime resume in
     the core to help drivers to implement more consistent runtime PM
     error handling (Rafael Wysocki)

   - Drop a redundant check from pm_runtime_force_resume() and rearrange
     documentation related to __pm_runtime_disable() (Rafael Wysocki)

   - Rework the handling of the "smart suspend" driver flag in the PM
     core to avoid issues hat may occur when drivers using it depend on
     some other drivers and clean up the related PM core code (Rafael
     Wysocki, Colin Ian King)

   - Fix the handling of devices with the power.direct_complete flag set
     if device_suspend() returns an error for at least one device to
     avoid situations in which some of them may not be resumed (Rafael
     Wysocki)

   - Use mutex_trylock() in hibernate_compressor_param_set() to avoid a
     possible deadlock that may occur if the "compressor" hibernation
     module parameter is accessed during the registration of a new
     ieee80211 device (Lizhi Xu)

   - Suppress sleeping parent warning in device_pm_add() in the case
     when new children are added under a device with the
     power.direct_complete set after it has been processed by
     device_resume() (Xu Yang)

   - Remove needless return in three void functions related to system
     wakeup (Zijun Hu)

   - Replace deprecated kmap_atomic() with kmap_local_page() in the
     hibernation core code (David Reaver)

   - Remove unused helper functions related to system sleep (David Alan
     Gilbert)

   - Clean up s2idle_enter() so it does not lock and unlock CPU offline
     in vain and update comments in it (Ulf Hansson)

   - Clean up broken white space in dpm_wait_for_children() (Geert
     Uytterhoeven)

   - Update the cpupower utility to fix lib version-ing in it and memory
     leaks in error legs, remove hard-coded values, and implement CPU
     physical core querying (Thomas Renninger, John B. Wyatt IV, Shuah
     Khan, Yiwei Lin, Zhongqiu Han)"

* tag 'pm-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (139 commits)
  PM: sleep: Fix bit masking operation
  dt-bindings: cpufreq: cpufreq-qcom-hw: Narrow properties on SDX75, SA8775p and SM8650
  dt-bindings: cpufreq: cpufreq-qcom-hw: Drop redundant minItems:1
  dt-bindings: cpufreq: cpufreq-qcom-hw: Add missing constraint for interrupt-names
  dt-bindings: cpufreq: cpufreq-qcom-hw: Add QCS8300 compatible
  cpufreq: Init cpufreq only for present CPUs
  PM: sleep: Fix handling devices with direct_complete set on errors
  cpuidle: Init cpuidle only for present CPUs
  PM: clk: Remove unused pm_clk_remove()
  PM: sleep: core: Fix indentation in dpm_wait_for_children()
  PM: s2idle: Extend comment in s2idle_enter()
  PM: s2idle: Drop redundant locks when entering s2idle
  PM: sleep: Remove unused pm_generic_ wrappers
  cpufreq: tegra186: Share policy per cluster
  cpupower: Make lib versioning scheme more obvious and fix version link
  PM: EM: Rework the depends on for CONFIG_ENERGY_MODEL
  PM: EM: Address RCU-related sparse warnings
  cpupower: Implement CPU physical core querying
  pm: cpupower: remove hard-coded topology depth values
  pm: cpupower: Fix cmd_monitor() error legs to free cpu_topology
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull power management updates from Rafael Wysocki:
 "These are dominated by cpufreq updates which in turn are dominated by
  updates related to boost support in the core and drivers and
  amd-pstate driver optimizations.

  Apart from the above, there are some cpuidle updates including a
  rework of the most recent idle intervals handling in the venerable
  menu governor that leads to significant improvements in some
  performance benchmarks, as the governor is now more likely to predict
  a shorter idle duration in some cases, and there are updates of the
  core device power management code, mostly related to system suspend
  and resume, that should help to avoid potential issues arising when
  the drivers of devices depending on one another want to use different
  optimizations.

  There is also a usual collection of assorted fixes and cleanups,
  including removal of some unused code.

  Specifics:

   - Manage sysfs attributes and boost frequencies efficiently from
     cpufreq core to reduce boilerplate code in drivers (Viresh Kumar)

   - Minor cleanups to cpufreq drivers (Aaron Kling, Benjamin Schneider,
     Dhananjay Ugwekar, Imran Shaik, zuoqian)

   - Migrate some cpufreq drivers to using for_each_present_cpu() (Jacky
     Bai)

   - cpufreq-qcom-hw DT binding fixes (Krzysztof Kozlowski)

   - Use str_enable_disable() helper in cpufreq_online() (Lifeng Zheng)

   - Optimize the amd-pstate driver to avoid cases where call paths end
     up calling the same writes multiple times and needlessly caching
     variables through code reorganization, locking overhaul and tracing
     adjustments (Mario Limonciello, Dhananjay Ugwekar)

   - Make it possible to avoid enabling capacity-aware scheduling (CAS)
     in the intel_pstate driver and relocate a check for out-of-band
     (OOB) platform handling in it to make it detect OOB before checking
     HWP availability (Rafael Wysocki)

   - Fix dbs_update() to avoid inadvertent conversions of negative
     integer values to unsigned int which causes CPU frequency selection
     to be inaccurate in some cases when the "conservative" cpufreq
     governor is in use (Jie Zhan)

   - Update the handling of the most recent idle intervals in the menu
     cpuidle governor to prevent useful information from being discarded
     by it in some cases and improve the prediction accuracy (Rafael
     Wysocki)

   - Make it possible to tell the intel_idle driver to ignore its
     built-in table of idle states for the given processor, clean up the
     handling of auto-demotion disabling on Baytrail and Cherrytrail
     chips in it, and update its MAINTAINERS entry (David Arcari, Artem
     Bityutskiy, Rafael Wysocki)

   - Make some cpuidle drivers use for_each_present_cpu() instead of
     for_each_possible_cpu() during initialization to avoid issues
     occurring when nosmp or maxcpus=0 are used (Jacky Bai)

   - Clean up the Energy Model handling code somewhat (Rafael Wysocki)

   - Use kfree_rcu() to simplify the handling of runtime Energy Model
     updates (Li RongQing)

   - Add an entry for the Energy Model framework to MAINTAINERS as
     properly maintained (Lukasz Luba)

   - Address RCU-related sparse warnings in the Energy Model code
     (Rafael Wysocki)

   - Remove ENERGY_MODEL dependency on SMP and allow it to be selected
     when DEVFREQ is set without CPUFREQ so it can be used on a wider
     range of systems (Jeson Gao)

   - Unify error handling during runtime suspend and runtime resume in
     the core to help drivers to implement more consistent runtime PM
     error handling (Rafael Wysocki)

   - Drop a redundant check from pm_runtime_force_resume() and rearrange
     documentation related to __pm_runtime_disable() (Rafael Wysocki)

   - Rework the handling of the "smart suspend" driver flag in the PM
     core to avoid issues hat may occur when drivers using it depend on
     some other drivers and clean up the related PM core code (Rafael
     Wysocki, Colin Ian King)

   - Fix the handling of devices with the power.direct_complete flag set
     if device_suspend() returns an error for at least one device to
     avoid situations in which some of them may not be resumed (Rafael
     Wysocki)

   - Use mutex_trylock() in hibernate_compressor_param_set() to avoid a
     possible deadlock that may occur if the "compressor" hibernation
     module parameter is accessed during the registration of a new
     ieee80211 device (Lizhi Xu)

   - Suppress sleeping parent warning in device_pm_add() in the case
     when new children are added under a device with the
     power.direct_complete set after it has been processed by
     device_resume() (Xu Yang)

   - Remove needless return in three void functions related to system
     wakeup (Zijun Hu)

   - Replace deprecated kmap_atomic() with kmap_local_page() in the
     hibernation core code (David Reaver)

   - Remove unused helper functions related to system sleep (David Alan
     Gilbert)

   - Clean up s2idle_enter() so it does not lock and unlock CPU offline
     in vain and update comments in it (Ulf Hansson)

   - Clean up broken white space in dpm_wait_for_children() (Geert
     Uytterhoeven)

   - Update the cpupower utility to fix lib version-ing in it and memory
     leaks in error legs, remove hard-coded values, and implement CPU
     physical core querying (Thomas Renninger, John B. Wyatt IV, Shuah
     Khan, Yiwei Lin, Zhongqiu Han)"

* tag 'pm-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (139 commits)
  PM: sleep: Fix bit masking operation
  dt-bindings: cpufreq: cpufreq-qcom-hw: Narrow properties on SDX75, SA8775p and SM8650
  dt-bindings: cpufreq: cpufreq-qcom-hw: Drop redundant minItems:1
  dt-bindings: cpufreq: cpufreq-qcom-hw: Add missing constraint for interrupt-names
  dt-bindings: cpufreq: cpufreq-qcom-hw: Add QCS8300 compatible
  cpufreq: Init cpufreq only for present CPUs
  PM: sleep: Fix handling devices with direct_complete set on errors
  cpuidle: Init cpuidle only for present CPUs
  PM: clk: Remove unused pm_clk_remove()
  PM: sleep: core: Fix indentation in dpm_wait_for_children()
  PM: s2idle: Extend comment in s2idle_enter()
  PM: s2idle: Drop redundant locks when entering s2idle
  PM: sleep: Remove unused pm_generic_ wrappers
  cpufreq: tegra186: Share policy per cluster
  cpupower: Make lib versioning scheme more obvious and fix version link
  PM: EM: Rework the depends on for CONFIG_ENERGY_MODEL
  PM: EM: Address RCU-related sparse warnings
  cpupower: Implement CPU physical core querying
  pm: cpupower: remove hard-coded topology depth values
  pm: cpupower: Fix cmd_monitor() error legs to free cpu_topology
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'pm-cpuidle'</title>
<updated>2025-03-24T13:43:30+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2025-03-24T13:43:30+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=7a9072d8599427679ab5e72a834af87bf818cae5'/>
<id>7a9072d8599427679ab5e72a834af87bf818cae5</id>
<content type='text'>
Merge cpuidle updates for 6.15-rc5, including a menu governor update
that is reported to improve some benchmark results quite significantly:

 - Update the handling of the most recent idle intervals in the menu
   cpuidle governor to prevent useful information from being discarded
   by it in some cases and improve the prediction accuracy (Rafael
   Wysocki).

 - Make it possible to tell the intel_idle driver to ignore its built-in
   table of idle states for the given processor, clean up the handling
   of auto-demotion disabling on Baytrail and Cherrytrail chips in it,
   and update its MAINTAINERS entry (David Arcari, Artem Bityutskiy,
   Rafael Wysocki).

 - Make some cpuidle drivers use for_each_present_cpu() instead of
   for_each_possible_cpu() during initialization to avoid issues
   occurring when nosmp or maxcpus=0 are used (Jacky Bai).

* pm-cpuidle:
  cpuidle: Init cpuidle only for present CPUs
  cpuidle: intel_idle: Update MAINTAINERS
  intel_idle: introduce 'no_native' module parameter
  cpuidle: menu: Update documentation after get_typical_interval() changes
  cpuidle: menu: Avoid discarding useful information
  cpuidle: menu: Eliminate outliers on both ends of the sample set
  cpuidle: menu: Tweak threshold use in get_typical_interval()
  cpuidle: menu: Use one loop for average and variance computations
  cpuidle: menu: Drop a redundant local variable
  intel_idle: clean up BYT/CHT auto demotion disable
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Merge cpuidle updates for 6.15-rc5, including a menu governor update
that is reported to improve some benchmark results quite significantly:

 - Update the handling of the most recent idle intervals in the menu
   cpuidle governor to prevent useful information from being discarded
   by it in some cases and improve the prediction accuracy (Rafael
   Wysocki).

 - Make it possible to tell the intel_idle driver to ignore its built-in
   table of idle states for the given processor, clean up the handling
   of auto-demotion disabling on Baytrail and Cherrytrail chips in it,
   and update its MAINTAINERS entry (David Arcari, Artem Bityutskiy,
   Rafael Wysocki).

 - Make some cpuidle drivers use for_each_present_cpu() instead of
   for_each_possible_cpu() during initialization to avoid issues
   occurring when nosmp or maxcpus=0 are used (Jacky Bai).

* pm-cpuidle:
  cpuidle: Init cpuidle only for present CPUs
  cpuidle: intel_idle: Update MAINTAINERS
  intel_idle: introduce 'no_native' module parameter
  cpuidle: menu: Update documentation after get_typical_interval() changes
  cpuidle: menu: Avoid discarding useful information
  cpuidle: menu: Eliminate outliers on both ends of the sample set
  cpuidle: menu: Tweak threshold use in get_typical_interval()
  cpuidle: menu: Use one loop for average and variance computations
  cpuidle: menu: Drop a redundant local variable
  intel_idle: clean up BYT/CHT auto demotion disable
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'cpuidle-menu'</title>
<updated>2025-02-25T11:13:52+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2025-02-25T11:13:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=de585eac08b972c86faa060a77263af3d209ed24'/>
<id>de585eac08b972c86faa060a77263af3d209ed24</id>
<content type='text'>
This work had been triggered by a report that commit 0611a640e60a
("eventpoll: prefer kfree_rcu() in __ep_remove()") had caused the
critical-jOPS metric of the SPECjbb 2015 benchmark [1] to drop by around
50% even though it generally reduced kernel overhead.  Indeed, it was
found during further investigation that the total interrupt rate while
running the SPECjbb workload had fallen as a result of that commit by
55% and the local timer interrupt rate had fallen by almost 80%.

That turned out to cause the menu cpuidle governor to select the deepest
idle state supplied by the cpuidle driver (intel_idle) much more often
which added significantly more idle state latency to the workload and
that led to the decrease of the critical-jOPS score.

Interestingly enough, this problem was not visible when the teo cpuidle
governor was used instead of menu, so it appeared to be specific to the
latter.  CPU wakeup event statistics collected while running the
workload indicated that the menu governor was effectively ignoring non-
timer wakeup information and all of its idle state selection decisions
appeared to be based on timer wakeups only.  Thus, it appeared that the
reduction of the local timer interrupt rate caused the governor to
predict a idle duration much more often while running the workload and
the deepest idle state was selected significantly more often as a result
of that.

A subsequent inspection of the get_typical_interval() function in the
menu governor indicated that it might return UINT_MAX too often which
then caused the governor's decisions to be based entirely on information
related to timers.

Generally speaking, UINT_MAX is returned by get_typical_interval() if it
cannot make a prediction based on the most recent idle intervals data
with sufficiently high confidence, but at least in some cases this means
that useful information is not taken into account at all which may lead
to significant idle state selection mistakes.  Moreover, this is not
really unlikely to happen.

One issue with get_typical_interval() is that, when it eliminates
outliers from the sample set in an attempt to reduce the standard
deviation (and so improve the prediction confidence), it does that by
dropping high-end samples only, while samples at the low end of the set
are retained.  However, the samples at the low end very well may be the
outliers and they should be eliminated from the sample set instead of
the high-end samples.  Accordingly, the likelihood of making a
meaningful idle duration prediction can be improved by making it also
eliminate low-end samples if they are farther from the average than
high-end samples.

Another issue is that get_typical_interval() gives up after eliminating
1/4 of the samples if the standard deviation is still not as low as
desired (within 1/6 of the average or within 20 us if the average is
close to 0), but the remaining samples in the set still represent useful
information at that point and discarding them altogether may lead to
suboptimal idle state selection.

For instance, the largest idle duration value in the get_typical_interval()
data set is the maximum idle duration observed recently and it is likely
that the upcoming idle duration will not exceed it.  Therefore, in the
absence of a better choice, this value can be used as an upper bound on
the target residency of the idle state to select.

* cpuidle-menu:
  cpuidle: menu: Update documentation after get_typical_interval() changes
  cpuidle: menu: Avoid discarding useful information
  cpuidle: menu: Eliminate outliers on both ends of the sample set
  cpuidle: menu: Tweak threshold use in get_typical_interval()
  cpuidle: menu: Use one loop for average and variance computations
  cpuidle: menu: Drop a redundant local variable
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
This work had been triggered by a report that commit 0611a640e60a
("eventpoll: prefer kfree_rcu() in __ep_remove()") had caused the
critical-jOPS metric of the SPECjbb 2015 benchmark [1] to drop by around
50% even though it generally reduced kernel overhead.  Indeed, it was
found during further investigation that the total interrupt rate while
running the SPECjbb workload had fallen as a result of that commit by
55% and the local timer interrupt rate had fallen by almost 80%.

That turned out to cause the menu cpuidle governor to select the deepest
idle state supplied by the cpuidle driver (intel_idle) much more often
which added significantly more idle state latency to the workload and
that led to the decrease of the critical-jOPS score.

Interestingly enough, this problem was not visible when the teo cpuidle
governor was used instead of menu, so it appeared to be specific to the
latter.  CPU wakeup event statistics collected while running the
workload indicated that the menu governor was effectively ignoring non-
timer wakeup information and all of its idle state selection decisions
appeared to be based on timer wakeups only.  Thus, it appeared that the
reduction of the local timer interrupt rate caused the governor to
predict a idle duration much more often while running the workload and
the deepest idle state was selected significantly more often as a result
of that.

A subsequent inspection of the get_typical_interval() function in the
menu governor indicated that it might return UINT_MAX too often which
then caused the governor's decisions to be based entirely on information
related to timers.

Generally speaking, UINT_MAX is returned by get_typical_interval() if it
cannot make a prediction based on the most recent idle intervals data
with sufficiently high confidence, but at least in some cases this means
that useful information is not taken into account at all which may lead
to significant idle state selection mistakes.  Moreover, this is not
really unlikely to happen.

One issue with get_typical_interval() is that, when it eliminates
outliers from the sample set in an attempt to reduce the standard
deviation (and so improve the prediction confidence), it does that by
dropping high-end samples only, while samples at the low end of the set
are retained.  However, the samples at the low end very well may be the
outliers and they should be eliminated from the sample set instead of
the high-end samples.  Accordingly, the likelihood of making a
meaningful idle duration prediction can be improved by making it also
eliminate low-end samples if they are farther from the average than
high-end samples.

Another issue is that get_typical_interval() gives up after eliminating
1/4 of the samples if the standard deviation is still not as low as
desired (within 1/6 of the average or within 20 us if the average is
close to 0), but the remaining samples in the set still represent useful
information at that point and discarding them altogether may lead to
suboptimal idle state selection.

For instance, the largest idle duration value in the get_typical_interval()
data set is the maximum idle duration observed recently and it is likely
that the upcoming idle duration will not exceed it.  Therefore, in the
absence of a better choice, this value can be used as an upper bound on
the target residency of the idle state to select.

* cpuidle-menu:
  cpuidle: menu: Update documentation after get_typical_interval() changes
  cpuidle: menu: Avoid discarding useful information
  cpuidle: menu: Eliminate outliers on both ends of the sample set
  cpuidle: menu: Tweak threshold use in get_typical_interval()
  cpuidle: menu: Use one loop for average and variance computations
  cpuidle: menu: Drop a redundant local variable
</pre>
</div>
</content>
</entry>
<entry>
<title>intel_idle: introduce 'no_native' module parameter</title>
<updated>2025-02-25T11:13:40+00:00</updated>
<author>
<name>David Arcari</name>
<email>darcari@redhat.com</email>
</author>
<published>2025-02-20T15:11:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=5e7e39ae15b0ea370e783a9326fdd1d91357fc3e'/>
<id>5e7e39ae15b0ea370e783a9326fdd1d91357fc3e</id>
<content type='text'>
Since commit 18734958e9bf ("intel_idle: Use ACPI _CST for processor models
without C-state tables") the intel_idle driver has had the ability to use
the ACPI _CST to populate C-states when the processor model is not
recognized.

However, even when the processor model is recognized (native mode) there
are cases where it is useful to make the driver ignore the per-CPU idle
states in lieu of ACPI C-states (such as specific application performance).

Add a new 'no_native' module parameter to provide this functionality.

Signed-off-by: David Arcari &lt;darcari@redhat.com&gt;
Link: https://patch.msgid.link/20250220151120.1131122-1-darcari@redhat.com
Reviewed-by: Artem Bityutskiy &lt;artem.bityutskiy@linux.intel.com&gt;
[ rjw: Spell CPU in capitals ]
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Since commit 18734958e9bf ("intel_idle: Use ACPI _CST for processor models
without C-state tables") the intel_idle driver has had the ability to use
the ACPI _CST to populate C-states when the processor model is not
recognized.

However, even when the processor model is recognized (native mode) there
are cases where it is useful to make the driver ignore the per-CPU idle
states in lieu of ACPI C-states (such as specific application performance).

Add a new 'no_native' module parameter to provide this functionality.

Signed-off-by: David Arcari &lt;darcari@redhat.com&gt;
Link: https://patch.msgid.link/20250220151120.1131122-1-darcari@redhat.com
Reviewed-by: Artem Bityutskiy &lt;artem.bityutskiy@linux.intel.com&gt;
[ rjw: Spell CPU in capitals ]
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>cpuidle: menu: Update documentation after get_typical_interval() changes</title>
<updated>2025-02-25T11:12:46+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2025-02-20T20:13:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=5c350410999653dff8d2975d794088e4c166e8b5'/>
<id>5c350410999653dff8d2975d794088e4c166e8b5</id>
<content type='text'>
The documentation of the menu cpuidle governor needs to be updated
to match the code behavior after some changes made recently.

No functional impact.

Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Reviewed-by: Christian Loehle &lt;christian.loehle@arm.com&gt;
Link: https://patch.msgid.link/4998484.31r3eYUQgx@rjwysocki.net
[ rjw: More specific subject, two typos fixed in the changelog ]
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The documentation of the menu cpuidle governor needs to be updated
to match the code behavior after some changes made recently.

No functional impact.

Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Reviewed-by: Christian Loehle &lt;christian.loehle@arm.com&gt;
Link: https://patch.msgid.link/4998484.31r3eYUQgx@rjwysocki.net
[ rjw: More specific subject, two typos fixed in the changelog ]
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>cpufreq: intel_pstate: Make it possible to avoid enabling CAS</title>
<updated>2025-02-18T19:47:33+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2025-01-27T13:07:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=7802fce7dc18394d041a1310fe4ad76120e08145'/>
<id>7802fce7dc18394d041a1310fe4ad76120e08145</id>
<content type='text'>
Capacity-aware scheduling (CAS) is enabled by default by intel_pstate on
hybrid systems without SMT, but in some usage scenarios it may be more
attractive to place tasks for maximum CPU performance regardless of the
extra cost in terms of energy, which is the case on such systems when
CAS is not enabled, so introduce a command line option to forbid
intel_pstate to enable CAS.

Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Acked-by:Srinivas Pandruvada &lt;srinivas.pandruvada@linux.intel.com&gt;
Link: https://patch.msgid.link/2781262.mvXUDI8C0e@rjwysocki.net
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Capacity-aware scheduling (CAS) is enabled by default by intel_pstate on
hybrid systems without SMT, but in some usage scenarios it may be more
attractive to place tasks for maximum CPU performance regardless of the
extra cost in terms of energy, which is the case on such systems when
CAS is not enabled, so introduce a command line option to forbid
intel_pstate to enable CAS.

Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Acked-by:Srinivas Pandruvada &lt;srinivas.pandruvada@linux.intel.com&gt;
Link: https://patch.msgid.link/2781262.mvXUDI8C0e@rjwysocki.net
</pre>
</div>
</content>
</entry>
<entry>
<title>cpufreq: Introduce an optional cpuinfo_avg_freq sysfs entry</title>
<updated>2025-02-17T18:09:31+00:00</updated>
<author>
<name>Beata Michalska</name>
<email>beata.michalska@arm.com</email>
</author>
<published>2025-01-31T16:24:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=fbb4a4759b541d09ebb8e391d5fa7f9a5a0cad61'/>
<id>fbb4a4759b541d09ebb8e391d5fa7f9a5a0cad61</id>
<content type='text'>
Currently the CPUFreq core exposes two sysfs attributes that can be used
to query current frequency of a given CPU(s): namely cpuinfo_cur_freq
and scaling_cur_freq. Both provide slightly different view on the
subject and they do come with their own drawbacks.

cpuinfo_cur_freq provides higher precision though at a cost of being
rather expensive. Moreover, the information retrieved via this attribute
is somewhat short lived as frequency can change at any point of time
making it difficult to reason from.

scaling_cur_freq, on the other hand, tends to be less accurate but then
the actual level of precision (and source of information) varies between
architectures making it a bit ambiguous.

The new attribute, cpuinfo_avg_freq, is intended to provide more stable,
distinct interface, exposing an average frequency of a given CPU(s), as
reported by the hardware, over a time frame spanning no more than a few
milliseconds. As it requires appropriate hardware support, this
interface is optional.

Note that under the hood, the new attribute relies on the information
provided by arch_freq_get_on_cpu, which, up to this point, has been
feeding data for scaling_cur_freq attribute, being the source of
ambiguity when it comes to interpretation. This has been amended by
restoring the intended behavior for scaling_cur_freq, with a new
dedicated config option to maintain status quo for those, who may need
it.

CC: Jonathan Corbet &lt;corbet@lwn.net&gt;
CC: Thomas Gleixner &lt;tglx@linutronix.de&gt;
CC: Ingo Molnar &lt;mingo@redhat.com&gt;
CC: Borislav Petkov &lt;bp@alien8.de&gt;
CC: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
CC: H. Peter Anvin &lt;hpa@zytor.com&gt;
CC: Phil Auld &lt;pauld@redhat.com&gt;
CC: x86@kernel.org
CC: linux-doc@vger.kernel.org

Signed-off-by: Beata Michalska &lt;beata.michalska@arm.com&gt;
Reviewed-by: Prasanna Kumar T S M &lt;ptsm@linux.microsoft.com&gt;
Reviewed-by: Sumit Gupta &lt;sumitg@nvidia.com&gt;
Acked-by: Viresh Kumar &lt;viresh.kumar@linaro.org&gt;
Acked-by: Rafael J. Wysocki &lt;rafael@kernel.org&gt;
Link: https://lore.kernel.org/r/20250131162439.3843071-3-beata.michalska@arm.com
Signed-off-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Currently the CPUFreq core exposes two sysfs attributes that can be used
to query current frequency of a given CPU(s): namely cpuinfo_cur_freq
and scaling_cur_freq. Both provide slightly different view on the
subject and they do come with their own drawbacks.

cpuinfo_cur_freq provides higher precision though at a cost of being
rather expensive. Moreover, the information retrieved via this attribute
is somewhat short lived as frequency can change at any point of time
making it difficult to reason from.

scaling_cur_freq, on the other hand, tends to be less accurate but then
the actual level of precision (and source of information) varies between
architectures making it a bit ambiguous.

The new attribute, cpuinfo_avg_freq, is intended to provide more stable,
distinct interface, exposing an average frequency of a given CPU(s), as
reported by the hardware, over a time frame spanning no more than a few
milliseconds. As it requires appropriate hardware support, this
interface is optional.

Note that under the hood, the new attribute relies on the information
provided by arch_freq_get_on_cpu, which, up to this point, has been
feeding data for scaling_cur_freq attribute, being the source of
ambiguity when it comes to interpretation. This has been amended by
restoring the intended behavior for scaling_cur_freq, with a new
dedicated config option to maintain status quo for those, who may need
it.

CC: Jonathan Corbet &lt;corbet@lwn.net&gt;
CC: Thomas Gleixner &lt;tglx@linutronix.de&gt;
CC: Ingo Molnar &lt;mingo@redhat.com&gt;
CC: Borislav Petkov &lt;bp@alien8.de&gt;
CC: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
CC: H. Peter Anvin &lt;hpa@zytor.com&gt;
CC: Phil Auld &lt;pauld@redhat.com&gt;
CC: x86@kernel.org
CC: linux-doc@vger.kernel.org

Signed-off-by: Beata Michalska &lt;beata.michalska@arm.com&gt;
Reviewed-by: Prasanna Kumar T S M &lt;ptsm@linux.microsoft.com&gt;
Reviewed-by: Sumit Gupta &lt;sumitg@nvidia.com&gt;
Acked-by: Viresh Kumar &lt;viresh.kumar@linaro.org&gt;
Acked-by: Rafael J. Wysocki &lt;rafael@kernel.org&gt;
Link: https://lore.kernel.org/r/20250131162439.3843071-3-beata.michalska@arm.com
Signed-off-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>cpuidle: menu: Update documentation after previous changes</title>
<updated>2025-01-13T19:41:39+00:00</updated>
<author>
<name>Rafael J. Wysocki</name>
<email>rafael.j.wysocki@intel.com</email>
</author>
<published>2025-01-10T12:46:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=56098a4505e7ba54c7942c82eeca8de522c8c2ee'/>
<id>56098a4505e7ba54c7942c82eeca8de522c8c2ee</id>
<content type='text'>
After commit 38f83090f515 ("cpuidle: menu: Remove iowait influence") and
other previous changes, the description of the menu governor in the
documentation does not match the code any more, so update it as
appropriate.

Fixes: 38f83090f515 ("cpuidle: menu: Remove iowait influence")
Fixes: 5484e31bbbff ("cpuidle: menu: Skip tick_nohz_get_sleep_length() call in some cases")
Reported-by: Artem Bityutskiy &lt;artem.bityutskiy@linux.intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Reviewed-by: Christian Loehle &lt;christian.loehle@arm.com&gt;
Link: https://patch.msgid.link/12589281.O9o76ZdvQC@rjwysocki.net
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
After commit 38f83090f515 ("cpuidle: menu: Remove iowait influence") and
other previous changes, the description of the menu governor in the
documentation does not match the code any more, so update it as
appropriate.

Fixes: 38f83090f515 ("cpuidle: menu: Remove iowait influence")
Fixes: 5484e31bbbff ("cpuidle: menu: Skip tick_nohz_get_sleep_length() call in some cases")
Reported-by: Artem Bityutskiy &lt;artem.bityutskiy@linux.intel.com&gt;
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Reviewed-by: Christian Loehle &lt;christian.loehle@arm.com&gt;
Link: https://patch.msgid.link/12589281.O9o76ZdvQC@rjwysocki.net
</pre>
</div>
</content>
</entry>
<entry>
<title>cpufreq/amd-pstate: Store the boost numerator as highest perf again</title>
<updated>2024-12-10T16:17:43+00:00</updated>
<author>
<name>Mario Limonciello</name>
<email>mario.limonciello@amd.com</email>
</author>
<published>2024-12-09T18:52:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=50a062a7620051c09adacd6d140ebd56881a333b'/>
<id>50a062a7620051c09adacd6d140ebd56881a333b</id>
<content type='text'>
commit ad4caad58d91d ("cpufreq: amd-pstate: Merge
amd_pstate_highest_perf_set() into amd_get_boost_ratio_numerator()")
changed the semantics for highest perf and commit 18d9b52271213
("cpufreq/amd-pstate: Use nominal perf for limits when boost is disabled")
worked around those semantic changes.

This however is a confusing result and furthermore makes it awkward to
change frequency limits and boost due to the scaling differences. Restore
the boost numerator to highest perf again.

Suggested-by: Dhananjay Ugwekar &lt;Dhananjay.Ugwekar@amd.com&gt;
Reviewed-by: Gautham R. Shenoy &lt;gautham.shenoy@amd.com&gt;
Fixes: ad4caad58d91 ("cpufreq: amd-pstate: Merge amd_pstate_highest_perf_set() into amd_get_boost_ratio_numerator()")
Link: https://lore.kernel.org/r/20241209185248.16301-2-mario.limonciello@amd.com
Signed-off-by: Mario Limonciello &lt;mario.limonciello@amd.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
commit ad4caad58d91d ("cpufreq: amd-pstate: Merge
amd_pstate_highest_perf_set() into amd_get_boost_ratio_numerator()")
changed the semantics for highest perf and commit 18d9b52271213
("cpufreq/amd-pstate: Use nominal perf for limits when boost is disabled")
worked around those semantic changes.

This however is a confusing result and furthermore makes it awkward to
change frequency limits and boost due to the scaling differences. Restore
the boost numerator to highest perf again.

Suggested-by: Dhananjay Ugwekar &lt;Dhananjay.Ugwekar@amd.com&gt;
Reviewed-by: Gautham R. Shenoy &lt;gautham.shenoy@amd.com&gt;
Fixes: ad4caad58d91 ("cpufreq: amd-pstate: Merge amd_pstate_highest_perf_set() into amd_get_boost_ratio_numerator()")
Link: https://lore.kernel.org/r/20241209185248.16301-2-mario.limonciello@amd.com
Signed-off-by: Mario Limonciello &lt;mario.limonciello@amd.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>cpufreq: docs: Reflect latency changes in docs</title>
<updated>2024-10-21T11:20:03+00:00</updated>
<author>
<name>Christian Loehle</name>
<email>christian.loehle@arm.com</email>
</author>
<published>2024-10-17T22:00:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.toradex.cn/cgit/linux-toradex.git/commit/?id=29dcbea92460e82181774b46f08b55a917615a97'/>
<id>29dcbea92460e82181774b46f08b55a917615a97</id>
<content type='text'>
There were two changes related to transition latency recently.
Namely commit e13aa799c2a6 ("cpufreq: Change default transition delay
to 2ms") and
commit 37c6dccd6837 ("cpufreq: Remove LATENCY_MULTIPLIER").

Both changed the defaults / maximums so let the documentation
reflect that.

Signed-off-by: Christian Loehle &lt;christian.loehle@arm.com&gt;
Link: https://patch.msgid.link/46853b6e-bad5-4ace-9b23-ff157f234ae3@arm.com
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
There were two changes related to transition latency recently.
Namely commit e13aa799c2a6 ("cpufreq: Change default transition delay
to 2ms") and
commit 37c6dccd6837 ("cpufreq: Remove LATENCY_MULTIPLIER").

Both changed the defaults / maximums so let the documentation
reflect that.

Signed-off-by: Christian Loehle &lt;christian.loehle@arm.com&gt;
Link: https://patch.msgid.link/46853b6e-bad5-4ace-9b23-ff157f234ae3@arm.com
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</pre>
</div>
</content>
</entry>
</feed>
