RAPL-INFO(1)

💖 RAPL-INFO 💖

okay bestie, gather round, we're talking about rapl-info — the little utility that gets RAPL configurations. That's Intel Running Average Power Limit, for the uninitiated. And yes, this is the rapl-info(1) manual page, we're doing this properly. 🫶

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✨ NAME ✨

rapl-info — get RAPL configurations 🌸

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✨ SYNOPSIS ✨

rapl-info [OPTION]...

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✨ DESCRIPTION ✨

okay so first things first, no cap: this utility is deprecated, use powercap-info(1) instead. 💀 Not me having to tell you this upfront but here we are.

It prints out Intel Running Average Power Limit (RAPL) configurations. Iconic behaviour honestly.

⚠️ Heads up bestie: the -p and -z options here are different from powercap-info(1). Do not get it twisted.

And the requirements, because she has standards 💅:

• An Intel processor (Sandy Bridge or newer)
• Linux kernel 3.13 or newer, compiled with CONFIG_POWERCAP and CONFIG_INTEL_RAPL enabled
• the intel_rapl kernel module to be loaded

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✨ OPTIONS ✨

• -h, --help — Prints out the help screen 🌈
• -v, --verbose — Print errors when files are not available. Basically she stops being mysterious and tells you what's missing. 👀
• -p, --zone=ZONE — The zone number (none by default; 0 by default if using -z/--subzone and/or -c/--constraint). Ending with a colon prevents output for subzones. E.g., for zone 0, but not subzones:

-p 0:

• -p, --package=PACKAGE — Deprecated, use --zone instead. bestie she's retired 💀
• -z, --subzone=SUBZONE — The subzone number (none by default)
• -c, --constraint=CONSTRAINT — The constraint number (none by default)

All remaining options below are mutually exclusive — pick ONE, you can't have them all, this isn't a buffet 🍓:

• -n, --nzones — Print the number of zones found, or the number of subzones found if -p/--zone is set

The following are zone-level arguments (-z/--subzone is optional):

• -j, --z-energy — Print zone energy counter ⚡
• -J, --z-max-energy-range — Print zone maximum energy counter range
• -w, --z-power — Print zone current power
• -W, --z-max-power-range — Print zone maximum current power range
• -e, --z-enabled — Print zone enable/disabled status
• -x, --z-name — Print zone name 🏷️

The following are constraint-level arguments and require -c/--constraint (-z/--subzone is optional):

• -l, --c-power-limit — Print constraint power limit
• -s, --c-time-window — Print constraint time window
• -U, --c-max-power — Print constraint maximum allowed power
• -u, --c-min-power — Print constraint minimum allowed power
• -T, --c-max-time-window — Print constraint maximum allowed time window
• -t, --c-min-time-window — Print constraint minimum allowed time window
• -y, --c-name — Print constraint name 🎀

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✨ EXAMPLES ✨

Note that -p/--zone=0 is used by default when also specifying -z/--subzone and/or -c/--constraint, allowing for simpler commands on single-socket systems. So convenient, we love a shortcut. 💅

• rapl-info — Print all RAPL zones.
• rapl-info -p 0 — Print only zone 0, which is usually named package-0.
• rapl-info -p 0 -z 1 — Print zone 0, subzone 1, which is usually the uncore or dram subzone of package-0, depending on the system.
• rapl-info -p 0 -c 1 — Print zone 0, constraint 1, which is usually the short_term constraint for package-0.
• rapl-info -p 0 -j — Print the energy counter for zone 0, which is usually named package-0.
• rapl-info -p 1 -z 0 -c 0 -l — Print the power limit for zone 1, subzone 0, constraint 0, which is usually the long_term constraint for the core subzone of package-1 (a multi-socket system).

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✨ REMARKS ✨

Some fields are optional and will only be printed if they are available — unless -v/--verbose is set. If no zone/constraint-specific outputs are requested, all available zones and constraints will be shown. Give the people what they want. 🌈

The units, memorise them bestie:

• Energy units: microjoules (uJ)
• Power units: microwatts (uW)
• Time units: microseconds (us)

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✨ BUGS ✨

okay so listen. The following are behavioral quirks due to the kernel interface or abnormalities in some hardware. They are not bugs in rapl-info and should not be reported as such. She's innocent, periodt. 🙈

• Values returned by the kernel sometimes lose accuracy from the actual values stored in Model-Specific Registers due to integer rounding. For example, the kernel may return a time window value of 7812 us, when in fact the actual stored value is 7812.5 us. Writing back a value returned by the kernel, e.g., using rapl-set(1), may cause unexpected changes to its value due to these rounding problems. 😭
• At the time of this writing, some features in the powercap interface are not supported by RAPL. The following options may result in ENOENT (No such file or directory) errors:
  • -w/--z-power
  • -W/--z-max-power-range
  • -u/--c-min-power
  • -T/--c-max-time-window
  • -t/--c-min-time-window
• On some systems, the constraint max_power_uw file, e.g., constraint_0_max_power_uw, is known to receive an ENODATA (No data available) error from the kernel for subzones. So even though the file exists, a value may not be printed for it. The file said hi but gave nothing. 💀
• It is possible for packages on multi-socket systems to be indexed out of order by the kernel. For example, the package at index 0 (-p 0) could actually be named package-1 while the package at index 1 (-p 1) is named package-0. Chaos, honestly. Not our fault. 🫠
• Report bugs upstream at <https://github.com/powercap/powercap> 🐛

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✨ FILES ✨

• /sys/devices/virtual/powercap/intel-rapl/*
• /sys/class/powercap/intel-rapl/*

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✨ AUTHORS ✨

Connor Imes <connor.k.imes@gmail.com> 👑

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✨ SEE ALSO ✨

powercap-info(1), powercap-set(1), rapl-set(1) — go read these too bestie, iykyk 🦋

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and that's the whole page!! this came from the powercap package, dated 2021-04-14, and honestly it ate. slay, stay powered, and go check your energy counters responsibly ✨💖🎀