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| author |   Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2025-05-26 21:18:34 +0200 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2025-05-26 21:18:34 +0200 |
| commit | af86d7e88e3069f19138cabb3d32dd1e39bf3f9e (patch) | |
| tree | 9edb54f721c8ca8229c364f9958dab189a19b83d /Documentation/admin-guide | |
| parent | Merge branch 'pm-cpufreq' (diff) | |
| parent | cpuidle: psci: Avoid initializing faux device if no DT idle states are present (diff) | |
| download | linux-rng-af86d7e88e3069f19138cabb3d32dd1e39bf3f9e.tar.xz linux-rng-af86d7e88e3069f19138cabb3d32dd1e39bf3f9e.zip | |
Merge branch 'pm-cpuidle'
Merge cpuidle updates for 6.16-rc1:
- Optimize bucket assignment when next_timer_ns equals KTIME_MAX in the
menu cpuidle governor (Zhongqiu Han).
- Convert the cpuidle PSCI driver to a faux device one (Sudeep Holla).
- Add C1 demotion on/off sysfs knob to the intel_idle driver (Artem
Bityutskiy).
- Fix typos in two comments in the teo cpuidle governor (Atul Kumar
Pant).
* pm-cpuidle:
cpuidle: psci: Avoid initializing faux device if no DT idle states are present
Documentation: ABI: testing: document the new cpuidle sysfs file
Documentation: admin-guide: pm: Document intel_idle C1 demotion
intel_idle: Add C1 demotion on/off sysfs knob
cpuidle: psci: Transition to the faux device interface
cpuidle: menu: Optimize bucket assignment when next_timer_ns equals KTIME_MAX
cpuidle: teo: Fix typos in two comments
Diffstat (limited to 'Documentation/admin-guide')
| -rw-r--r-- | Documentation/admin-guide/pm/intel_idle.rst | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/Documentation/admin-guide/pm/intel_idle.rst b/Documentation/admin-guide/pm/intel_idle.rst index 5940528146eb..ed6f055d4b14 100644 --- a/Documentation/admin-guide/pm/intel_idle.rst +++ b/Documentation/admin-guide/pm/intel_idle.rst @@ -38,6 +38,27 @@ instruction at all. only way to pass early-configuration-time parameters to it is via the kernel command line. +Sysfs Interface +=============== + +The ``intel_idle`` driver exposes the following ``sysfs`` attributes in +``/sys/devices/system/cpu/cpuidle/``: + +``intel_c1_demotion`` + Enable or disable C1 demotion for all CPUs in the system. This file is + only exposed on platforms that support the C1 demotion feature and where + it was tested. Value 0 means that C1 demotion is disabled, value 1 means + that it is enabled. Write 0 or 1 to disable or enable C1 demotion for + all CPUs. + + The C1 demotion feature involves the platform firmware demoting deep + C-state requests from the OS (e.g., C6 requests) to C1. The idea is that + firmware monitors CPU wake-up rate, and if it is higher than a + platform-specific threshold, the firmware demotes deep C-state requests + to C1. For example, Linux requests C6, but firmware noticed too many + wake-ups per second, and it keeps the CPU in C1. When the CPU stays in + C1 long enough, the platform promotes it back to C6. This may improve + some workloads' performance, but it may also increase power consumption. .. _intel-idle-enumeration-of-states: |