RAPL plugin
The RAPL plugin creates an Alumet source that collects measurements of processor energy usage via RAPL interfaces, such as perf-events and powercap.
Requirements
- RAPL-compatible processor
- Linux (the plugin relies on abstractions provided by the kernel - perf-events and powercap)
- Specific for perf-events usage: See perf_event_paranoid and capabilities requirements.
- Specific for powercap usage: Ensure read access to everything in
/sys/devices/virtual/powercap/intel-rapl(eg:sudo chmod a+r -R /sys/devices/virtual/powercap/intel-rapl). - Specific for containers: Read this documentation about rapl plugin capabilities.
Metrics
Here are the metrics collected by the plugin source.
| Name | Type | Unit | Description | Attributes | More information |
|---|---|---|---|---|---|
rapl_consumed_energy | Counter Diff | joule | Energy consumed since the previous measurement | domain |
Attributes
Domain
A domain is a specific area of power consumption tracked by RAPL. The possible domain values are:
| Value | Description |
|---|---|
platform | the entire machine - ⚠️ may vary depending on the model |
package | the CPU cores, the iGPU, the L3 cache and the controllers |
pp0 | the CPU cores |
pp1 | the iGPU |
dram | the RAM attached to the processor |
Configuration
Here is a configuration example of the RAPL plugin. It's part of the Alumet configuration file (eg: alumet-config.toml).
[plugins.rapl]
# Interval between two RAPL measurements.
poll_interval = "1s"
# Interval between two flushing of RAPL measurements.
flush_interval = "5s"
# Set to true to disable perf-events and always use the powercap sysfs.
no_perf_events = false
More information
Should I use perf-events or powercap ?
Both interfaces provide similar energy consumption data, but we recommend using perf-events for lower measurement overhead (especially in high-frequency polling scenarios).
For a more detailed technical comparison, see this publication on RAPL measurement methods.
perf_event_paranoid and capabilities
You should read this section in case you're using perf-events to collect measurements.
perf_event_paranoid is a Linux kernel setting that controls the level of access that unprivileged (non-root) users have to access features provided by the perf subsystem which can be used in this plugin (should I use perf-events or powercap).
Below is a summary of how different perf_event_paranoid values affect RAPL plugin functionality when running as an unprivileged user:
perf_event_paranoid value | Description | Required capabilities (binary) | RAPL plugin works (unprivileged) |
|---|---|---|---|
| 4 (Debian-based systems only) | Disables all perf event usage for unprivileged users | – | ❌ Not supported |
| 2 | Allows only user-space measurements | cap_perfmon (or cap_sys_admin for Linux < 5.8) | ✅ Supported |
| 1 | Allows user-space and kernel-space measurements | cap_perfmon (or cap_sys_admin for Linux < 5.8) | ✅ Supported |
| 0 | Allows user-space, kernel-space, and CPU-specific data | cap_perfmon (or cap_sys_admin for Linux < 5.8) | ✅ Supported |
| -1 | Full access, including raw tracepoints | – | ✅ Supported |
Example for setting perf_event_paranoid: sudo sysctl -w kernel.perf_event_paranoid=2 will set the value to 2.
Note that this command will not make it permanent (reset after restart).
Alternatively, you can run Alumet as a privileged user (root), but this is not recommended for security reasons.