jouleclaw-energy: RAPL reads each package's energy-status MSR where powercap lists none #618

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dcharlot merged 2 commits from jouleclaw-energy/rapl-msr into main 2026-11-05 04:28:34 -05:00

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dcharlot commented 2026-11-04 14:39:51 -05:00

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Some kernels ship without the powercap RAPL driver (Ubuntu without
linux-modules-extra, as on some rented bare-metal servers), so
/sys/class/powercap lists no package while the counters are there, and the
RAPL counter was unavailable on hosts that can measure. Where powercap lists
no package, the counter now reads the same counters directly: each package's
MSR_PKG_ENERGY_STATUS (0x611, Intel family 6; 0xC001029B, AMD Zen and Hygon)
through /dev/cpu//msr, the 32-bit count converted at
the package's own unit (bits 12:8 of the power-unit MSR), so it wraps at 2^32
counts in microjoules and resolves one count (62 uJ at 2^-14 J). A power-unit
MSR that reads zero is no counter (KVM guests read zeros). Powercap is still
preferred, and the liveness rule is unchanged: every package readable and live,
or no figure.

On two bare-metal Supermicro servers with no powercap zone, as root: a Xeon
E-2278G live, 59.8 J over 2.0 s, 29.9 W; two Xeon Silver 4215R sockets,
summed, live, 155.0 J over 2.0 s, 77.5 W. As an unprivileged user (no
CAP_SYS_RAWIO) the counter is Unavailable and the meter falls through.

Tests: fake device files (a register's bytes at its offset) cover a two-socket
host read on each package's first CPU, the 32-bit wrap, AMD's registers, a zero
unit, an unknown CPU, a missing device, powercap preferred, and the production
probe over MSR packages. Unit tests pass on Linux and macOS; clippy is clean on
macOS (default, ioreport, rapl).

Second commit: die scope

Linux scopes Intel's RAPL MSRs per die and AMD's and Hygon's per package. arch/x86/events/rapl.c says "AMD/HYGON platforms have a per-PKG package energy counter" and "CLX-AP is multi-die and its RAPL MSRs are die-scope". The powercap driver names a multi-die Intel package's zones package-<p>-die-<d>, one top-level zone per die.

• MSR fallback: reading each package on its first CPU counted one die of a multi-die Intel package, an under-count. A domain is now (physical_package_id, die_id) on Intel and the package on AMD and Hygon. Each domain is read on its own first CPU and they are summed. Single-die parts are unchanged.
• Powercap names: the rule now also accepts package-<n>-die-<m>, so a multi-die host's die zones count as packages. It accepts nothing looser.
• Hardware test oracle: scopes MSR domains the same way, using its own code.

New unit tests: a two-die Intel package is two domains, summed; an AMD package whose CPUs list several die_ids is one domain; a two-die powercap tree sums both die zones; and the name rule's accepted names and near misses. Tests and clippy pass as before on Linux and macOS.

🤖 Generated with Claude Code

Some kernels ship without the powercap RAPL driver (Ubuntu without linux-modules-extra, as on some rented bare-metal servers), so /sys/class/powercap lists no package while the counters are there, and the RAPL counter was unavailable on hosts that can measure. Where powercap lists no package, the counter now reads the same counters directly: each package's MSR_PKG_ENERGY_STATUS (0x611, Intel family 6; 0xC001029B, AMD Zen and Hygon) through /dev/cpu/<first cpu of the package>/msr, the 32-bit count converted at the package's own unit (bits 12:8 of the power-unit MSR), so it wraps at 2^32 counts in microjoules and resolves one count (62 uJ at 2^-14 J). A power-unit MSR that reads zero is no counter (KVM guests read zeros). Powercap is still preferred, and the liveness rule is unchanged: every package readable and live, or no figure. On two bare-metal Supermicro servers with no powercap zone, as root: a Xeon E-2278G live, 59.8 J over 2.0 s, 29.9 W; two Xeon Silver 4215R sockets, summed, live, 155.0 J over 2.0 s, 77.5 W. As an unprivileged user (no CAP_SYS_RAWIO) the counter is Unavailable and the meter falls through. Tests: fake device files (a register's bytes at its offset) cover a two-socket host read on each package's first CPU, the 32-bit wrap, AMD's registers, a zero unit, an unknown CPU, a missing device, powercap preferred, and the production probe over MSR packages. Unit tests pass on Linux and macOS; clippy is clean on macOS (default, ioreport, rapl). ## Second commit: die scope Linux scopes Intel's RAPL MSRs per die and AMD's and Hygon's per package. `arch/x86/events/rapl.c` says "AMD/HYGON platforms have a per-PKG package energy counter" and "CLX-AP is multi-die and its RAPL MSRs are die-scope". The powercap driver names a multi-die Intel package's zones `package-<p>-die-<d>`, one top-level zone per die. - **MSR fallback:** reading each package on its first CPU counted one die of a multi-die Intel package, an under-count. A domain is now (`physical_package_id`, `die_id`) on Intel and the package on AMD and Hygon. Each domain is read on its own first CPU and they are summed. Single-die parts are unchanged. - **Powercap names:** the rule now also accepts `package-<n>-die-<m>`, so a multi-die host's die zones count as packages. It accepts nothing looser. - **Hardware test oracle:** scopes MSR domains the same way, using its own code. New unit tests: a two-die Intel package is two domains, summed; an AMD package whose CPUs list several `die_id`s is one domain; a two-die powercap tree sums both die zones; and the name rule's accepted names and near misses. Tests and clippy pass as before on Linux and macOS. 🤖 Generated with [Claude Code](https://claude.com/claude-code)

dcharlot added 1 commit 2026-11-04 14:39:52 -05:00

jouleclaw-energy: RAPL reads each package's energy-status MSR where powercap lists none ... 32d27b06fd

Some kernels ship without the powercap RAPL driver (Ubuntu without
linux-modules-extra, as on some rented bare-metal servers), so
/sys/class/powercap lists no package while the counters are there, and the
RAPL counter was unavailable on hosts that can measure. Where powercap lists
no package, the counter now reads the same counters directly: each package's
MSR_PKG_ENERGY_STATUS (0x611, Intel family 6; 0xC001029B, AMD Zen and Hygon)
through /dev/cpu/<first cpu of the package>/msr, the 32-bit count converted at
the package's own unit (bits 12:8 of the power-unit MSR), so it wraps at 2^32
counts in microjoules and resolves one count (62 uJ at 2^-14 J). A power-unit
MSR that reads zero is no counter (KVM guests read zeros). Powercap is still
preferred, and the liveness rule is unchanged: every package readable and live,
or no figure.

On two bare-metal Supermicro servers with no powercap zone, as root: a Xeon
E-2278G live, 59.8 J over 2.0 s, 29.9 W; two Xeon Silver 4215R sockets,
summed, live, 155.0 J over 2.0 s, 77.5 W. As an unprivileged user (no
CAP_SYS_RAWIO) the counter is Unavailable and the meter falls through.

Tests: fake device files (a register's bytes at its offset) cover a two-socket
host read on each package's first CPU, the 32-bit wrap, AMD's registers, a zero
unit, an unknown CPU, a missing device, powercap preferred, and the production
probe over MSR packages. Unit tests pass on Linux and macOS; clippy is clean on
macOS (default, ioreport, rapl).

Co-Authored-By: Claude Opus 5.5 <[email protected]>

dcharlot referenced this pull request 2026-11-04 20:00:33 -05:00

jouleclaw-energy: a Mac's whole-machine power from the SMC (EnergyDomain::System, ModelBased) #622

dcharlot referenced this pull request 2026-11-04 21:02:16 -05:00

jcp-energy: RAPL reads each package's energy-status MSR where powercap lists none #625

dcharlot referenced this pull request 2026-11-04 21:02:21 -05:00

proof-cascade: RAPL reads each package's energy-status MSR where powercap lists none #626

dcharlot referenced this pull request 2026-11-04 21:02:27 -05:00

eoc-meter: RAPL reads each package's energy-status MSR where powercap lists none #627

dcharlot added 1 commit 2026-11-04 21:20:30 -05:00

jouleclaw-energy: RAPL MSR domains are per die on Intel, per package on AMD; die zones are packages ... b9bf223411

Linux scopes Intel's RAPL MSRs per die and AMD's and Hygon's per package
(arch/x86/events/rapl.c: "AMD/HYGON platforms have a per-PKG package energy
counter", "CLX-AP is multi-die and its RAPL MSRs are die-scope"), and the
powercap driver names a multi-die Intel package's zones package-<p>-die-<d>,
one top-level zone per die. Two consequences, both corrected here:

- The MSR fallback read each package on its first CPU, so on a multi-die Intel
  package it counted one die: an under-count, the unsafe direction at a
  ceiling. A domain is now (physical_package_id, die_id) on Intel (die 0
  where die_id is absent) and the package on AMD and Hygon, each read on its
  own lowest-numbered CPU and summed. Single-die parts are unchanged.
- The name rule accepted only package-<n>, so a multi-die host's die zones
  were not packages: no powercap package was listed. It now also accepts
  package-<n>-die-<m>, and nothing looser.

tests/rapl_hardware.rs read powercap only, so on a host with no powercap
package its oracle called the counters Unreadable while the meter, as root,
read them live through the MSRs, and the burn test had no zone to bracket.
The oracle now reads the MSRs itself where powercap lists no package, scoped
the same way, and brackets the meter's figure with outer and inner MSR reads.

On two bare-metal servers with no powercap zone (Xeon E-2278G; two Xeon
Silver 4215R sockets), the hardware tests now pass as root (oracle and meter
Live; 6.68 J and 22.07 J over a 300 ms burn, inside the oracle's MSR bracket)
and unprivileged (both Unavailable, the meter the estimator).

Tests: a two-die Intel package is two domains read on their own first CPUs
and summed; an AMD package whose CPUs list several die_ids is one domain; a
two-die powercap tree sums both die zones and not psys; the name rule's
accepts and near misses. Linux: unit and hardware tests pass (rapl,nvml);
macOS: unit tests pass, clippy clean in default, ioreport and rapl.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

dcharlot referenced this pull request 2026-11-04 21:21:04 -05:00

sandbox-meter: RAPL reads each domain's energy-status MSR where powercap lists none; die zones are packages #629

dcharlot merged commit 690a31dfcf into main 2026-11-05 04:28:34 -05:00

dcharlot referenced this pull request from a commit 2026-11-05 04:28:35 -05:00

Merge pull request 'jouleclaw-energy: RAPL reads each package's energy-status MSR where powercap lists none' (#618) from jouleclaw-energy/rapl-msr into main

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Transaction-Science/open-standards!618

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