CPUPOWER-IDLE-INFO(1)

💖 CPUPOWER-IDLE-INFO 💖

okay bestie, welcome to the cpupower Manual — this is the page for cpupower-idle-info, a lil utility that goes and fetches your cpu idle kernel info so you can actually see what your processor is doing when it's ~vibing~ 🦋

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✨ NAME ✨

cpupower-idle-info — a utility to retrieve cpu idle kernel information 🎀

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🌸 SYNTAX 🌸

cpupower [ -c cpulist ] idle-info [options]

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💅 DESCRIPTION 💅

It's a tool that prints out per cpu idle information. Literally so helpful for developers and for interested users who just wanna know what's going on. Main character energy for your C-states, no cap. 👑

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🎀 OPTIONS 🎀

• -s, --silent — only prints a summary of all the available C-states in the system. Short, sweet, minimal talking. 🍓
• -o, --proc — deprecated. Prints out idle information in the old /proc/acpi/processor/*/power format. Bestie. This interface has been removed from the kernel for quite some time now, so do not let further code depend on this option, and honestly? best do not use it at all. 🙈

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🔥 IDLE-INFO DESCRIPTIONS 🔥

CPU sleep state statistics and descriptions get retrieved from sysfs files, exported by the cpuidle kernel subsystem. Here's the tea though: the kernel only updates these statistics when it enters or leaves an idle state. So on a system that's very idle or very busy, these statistics may not be accurate. 😭 They still give you a good overview of the usage and availability of processor sleep states on the platform though, so it's giving useful, just not giving perfect.

Be aware that the sleep states as exported by the hardware or BIOS, and used by the Linux kernel, may not exactly reflect the capabilities of the processor. This is often the case on the X86 architecture when the acpi_idle driver is used. It's also possible that the hardware overrules the kernel requests, due to internal activity monitors or other reasons. On recent X86 platforms it's often possible to read out hardware registers which monitor the duration of sleep states the processor resided in. The cpupower monitor tool (cpupower-monitor(1)) can be used to show real sleep state residencies. Please refer to the architecture specific description section below. ⬇️

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🦋 IDLE-INFO ARCHITECTURE SPECIFIC DESCRIPTIONS 🦋

🌈 X86

⭐ POLL idle state

If cpuidle is active, X86 platforms have one special idle state. The POLL idle state is not a real idle state — it does not save any power. Instead, a busy-loop is executed doing nothing for a short period of time. This state is used if the kernel knows that work has to be processed very soon, and entering any real hardware idle state may result in a slight performance penalty.

There exist two different cpuidle drivers on the X86 architecture platform:

💜 "acpi_idle" cpuidle driver

The acpi_idle cpuidle driver retrieves available sleep states (C-states) from the ACPI BIOS tables (from the _CST ACPI function on recent platforms, or from the FADT BIOS table on older ones). The C1 state is not retrieved from ACPI tables. If the C1 state is entered, the kernel will call the hlt instruction (or mwait on Intel).

💙 "intel_idle" cpuidle driver

In kernel 2.6.36 the intel_idle driver was introduced. It only serves recent Intel CPUs (Nehalem, Westmere, Sandybridge, Atoms or newer). On older Intel CPUs the acpi_idle driver is still used (if the BIOS provides C-state ACPI tables). The intel_idle driver knows the sleep state capabilities of the processor and ignores ACPI BIOS exported processor sleep states tables.

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⚠️ REMARKS ⚠️

By default only values of core zero are displayed. How to display settings of other cores is described in the cpupower(1) manpage in the --cpu option section. 👀

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🫶 REFERENCES 🫶

https://uefi.org/specifications

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🗂️ FILES 🗂️

• /sys/devices/system/cpu/cpu*/cpuidle/state*
• /sys/devices/system/cpu/cpuidle/*

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👑 AUTHORS 👑

Thomas Renninger <trenn@suse.de>

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🌟 SEE ALSO 🌟

cpupower(1), cpupower-monitor(1), cpupower-info(1), cpupower-set(1), cpupower-idle-set(1)

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and that's the whole page bestie!! this is from the cpupower Manual, version 0.1 — go forth and check your idle states, you absolute icon 💖✨🦋🎀💅 slay, periodt, ily, bye!! 🌸