Machine Baseline Checks

GMT can verify a set of hardware and OS properties before every measurement run. All checks are configured under the machine: key in config.yml.

Every check is opt-in: omitting a key (or setting it to null / False) silently skips that check. A failed check emits a WARN and, depending on system_check_threshold, may abort the run.

Temperature#

GMT reads the current temperature from a hardware sensor chip and compares it against a configured baseline. If the machine is outside the expected range the run is held until the temperature stabilises.

machine:
  base_temperature_chip: "acpitz-acpi-0"   # sensor chip name (from `sensors`)
  base_temperature_feature: "temp1"         # feature name on that chip
  base_temperature_value: 65               # maximum acceptable °C

The current temperature is always written to machines.current_temperature in the database. Status events (cooldown, warmup) include the exact temperature reading in their data column.

To find the right chip and feature names:

sensors
# or for JSON output:
sensors -j

Also see Accuracy Control →.

RAPL Power Capping#

Verifies that RAPL power limits are at or below the values you have locked on the machine. Ensures a consistent thermal envelope across cluster nodes.

machine:
  rapl_power_capping:
    package: 35    # Watts — per-socket CPU package limit
    dram: 10       # Watts — DRAM controller limit
    psys: 65       # Watts — platform-wide limit (if available)

Each sub-key is independent; omit any you do not want to enforce. Values are compared against the constraint_0_power_limit_uw sysfs files under /sys/devices/virtual/powercap/intel-rapl/.

To read the current limits on your machine:

cat /sys/devices/virtual/powercap/intel-rapl/intel-rapl:*/constraint_0_power_limit_uw

Also see NOP Linux → for how to make these limits persistent across reboots.

Docker Registry Mirror#

Confirms that the Docker daemon is configured to use a specific registry mirror (e.g. a local cache).

machine:
  docker_registry_url: "https://registry.example.com"

The check runs docker info and looks for the URL in the Registry Mirrors section. Also see Container Registry →.

CPU Core Count#

Verifies the total number of logical CPUs (threads, including SMT/HT siblings).

machine:
  cpu_cores: 16

Detects hot-plug events or unexpected changes in Hyper-Threading state. If cpu_smt is also configured, the two checks complement each other.

Installed RAM#

Verifies total installed RAM in whole gigabytes.

machine:
  dram_gb: 64

Detects failed or removed DIMMs.

USB Device Allowlist#

Warns when any connected USB device is not present in the allowlist. Each entry is matched as a substring against lsusb output lines.

machine:
  usb_devices:
    - "8087:0026"          # Intel USB hub
    - "046d:c52b"          # Logitech Unifying Receiver
    - "Linux Foundation"   # internal root hubs

Run lsusb on your machine to collect the expected entries. The check is skipped on macOS and Windows.

PCI Device Allowlist#

Warns when any connected PCI device is not present in the allowlist. Each entry is matched as a substring against lspci output lines.

machine:
  pci_devices:
    - "Network controller"
    - "SATA controller"
    - "VGA compatible controller"

Run lspci on your machine to collect the expected entries. The check is skipped on macOS and Windows.

CPU Scaling Governor#

Verifies that all CPU cores use the expected frequency scaling governor. Governor changes after a reboot are one of the most common silent causes of measurement variance.

machine:
  cpu_governor: "performance"

Reads /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor. To lock the governor:

echo performance | sudo tee /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
# or
sudo cpupower frequency-set -g performance

Also see NOP Linux →.

CPU Frequency#

Verifies that the current frequency of every CPU core is within ±10 MHz of the configured value. Useful when frequency scaling is fully locked (e.g. intel_pstate with min = max).

machine:
  cpu_frequency_mhz: 3000

CPU Scaling Driver#

Verifies that the cpufreq scaling driver matches the expected value on all cores.

machine:
  cpu_scaling_driver: "intel_pstate"   # or "acpi-cpufreq", "cppc_cpufreq", etc.

A different driver can apply different power and frequency policies even when the governor setting appears identical.

SMT / Hyper-Threading#

Verifies whether Simultaneous Multi-Threading (Intel HT / AMD SMT) is enabled or disabled.

machine:
  cpu_smt: false   # true = SMT must be enabled, false = SMT must be disabled

Reads /sys/devices/system/cpu/smt/active. To disable SMT:

echo off | sudo tee /sys/devices/system/cpu/smt/control
# For a permanent change add "nosmt" to GRUB_CMDLINE_LINUX in /etc/default/grub

CPU Turbo Boost#

Verifies whether CPU frequency boost (Intel Turbo Boost / AMD Boost) is enabled or disabled.

machine:
  cpu_turbo_boost: false   # true = boost must be on, false = boost must be off

To disable Turbo Boost (Intel):

echo 1 | sudo tee /sys/devices/system/cpu/intel_pstate/no_turbo

System-wide Systemd Timers#

This check runs as root and warns when any active system-wide systemd timer is detected. Timers can wake the system and create measurement noise.

This check is not configured via config.yml — it always runs on Linux. To inspect active timers:

systemctl --all list-timers

Also see NOP Linux → for a full list of services and timers to disable on cluster machines.

All checks at a glance#