intel_lpmd_config.xml - Man Page

$(TDCONFDIR)/etc/intel_lpmd/intel_lpmd_config.xml

intel_lpmd_config.xml is a configuration file for the Intel Low Power Mode Daemon. It is used to describe the lp_mode_cpus to use in Low Power Mode, as well as the way to restrict work to those CPUs. It also describes if and how the HFI monitor and utilization monitor works. The location of this file depends on the configuration option used during build time.

lp_mode_cpus is a set of active CPUs when system is in Low Power Mode. This usually equals a group of most power efficient CPUs on a platform to achieve best power saving. When not specified, intel_lpmd tool can detect this automatically. E.g. it uses an E-core Module on Intel Alderlake platform, and it uses the Low Power E-cores on SoC Die on Intel Meteorlake platform.

Mode specifies the way to migrate the tasks to the lp_mode_cpus.

• Mode 0: set cpuset to the lp_mode_cpus for systemd. All tasks created by systemd will run on these CPUs only. This is supported for cgroup v2 based systemd only.
• Mode 1: Isolate the non-lp_mode_cpus so that tasks are scheduled to the lp_mode_cpus only.
• Mode 2: Force idle injection to the non-lp_mode_cpus and leverage the scheduler to schedule the other tasks to the lp_mode_cpus.

PerformanceDef specifies the default behavior when power setting is set to Performance.

• -1 : Never enter Low Power Mode.
• 0 : opportunistic Low Power Mode enter/exit based on HFI/Utilization request.
• 1 : Always stay in Low Power Mode.

BalancedDef specifies the default behavior when power setting is set to Balanced.

PowersaverDef specifies the default behavior when power setting is set to Power saver.

HfiLpmEnable specifies if the HFI monitor can capture the HFI hints for Low Power Mode.

HfiSuvEnable specifies if the HFI monitor can capture the HFI hints for survivability mode.

WLTHintEnable Enable use of hardware Workload type hints.

util_entry_threshold specifies the system utilization threshold for entering Low Power Mode. The system workload is considered to fit the lp_mode_cpus capacity when system utilization is under this threshold. Setting to 0 or leaving this empty disables the utilization monitor.

util_exit_threshold specifies the CPU utilization threshold for exiting Low Power Mode. The system workload is considered to not fit the lp_mode_cpus capacity when the utilization of the busiest lp_mode_cpus is above this threshold. Setting to 0 or leaving this empty disables the utilization monitor.

EntryDelayMS specifies the sample interval used by the utilization Monitor when system wants to enter Low Power Mode based on system utilization. Setting to 0 or leaving this empty will cause the utilization Monitor to use the default interval, 1000 milli seconds.

ExitDelayMS specifies the sample interval used by the utilization Monitor when system wants to exit Low Power Mode based on CPU utilization. Setting to 0 or leaving this empty will cause the utilization Monitor to use the adaptive value. The adaptive interval is based on CPU utilization. The busier the CPU is, the shorter interval the utilization monitor uses.

EntryHystMS specifies a hysteresis threshold when system is in Low Power Mode. If set, when the previous average time stayed in Low Power Mode is lower than this value, the current enter Low Power Mode request will be ignored because it is expected that the system will exit Low Power Mode soon. Setting to 0 or leaving this empty disables this hysteresis algorithm.

ExitHystMS specifies a hysteresis threshold when system is not in Low Power Mode. If set, when the previous average time stayed out of Low-Power-Mode is lower than this value, the current exit Low Power Mode request will be ignored because it is expected that the system will enter Low Power Mode soon. Setting to 0 or leaving this empty disables this hysteresis algorithm.

IgnoreITMT Avoid changing scheduler ITMT flag. This means that during transition to low power mode, ITMT flag is not changed. This reduces latency during switching. This flag is not used when configuration uses "State" based configuration, where this flag can be defined per state.

States Allows to define per platform low power states. Each state defines has an entry condition and set of parameters to use.

There can be multiple State configuration can be present. Each configuration is valid for a platform. A State header defines parameters, which are used to match a platform. CPUFamily CPU generation to match.

CPUModel CPU model to match.

CPUConfig Define a configuration of CPUs and TDP to match different skews for the same CPU model and family. CPU configuration string format is: xPyEzL-tdpW. For example: 12P8E2L-28W, defines a platform with 6 P-cores with hyper threading enabled, 8 E cores, 2 LPE cores and the TDP is 28W. This configuration allows wildcard "*" to match any combination.

Each "State" defines entry criteria and parameters to use. ID A unique ID for the state.

Name A name for the state.

EntrySystemLoadThres System Entry load threshold in percent. System utilization is different based on the number of CPUs are active in a configuration. This value is calculated from /proc/stat sysfs. To enter into this state, the system utilization must be less or equal to this value.

EnterCPULoadThres CPU Entry load threshold in percent. Per CPU utilization is also obtained from /proc/stat. To enter into this state any active CPU utilization must be less or equal to this value. EnterCPULoadThres is checked before EntrySystemLoadThres to match a state.

WLTType Workload type value to enter into this state. If this value is defined then utilization based entry triggers are not used. To use this WLTHintEnable must be enabled, so that hardware notifications are enabled.

ActiveCPUs Active CPUs in this state. The list can be comma separated or use "-" for a range. This is optional to have active CPUs in a state.

EPP EPP to apply for this state. -1 to ignore.

EPB EPB to apply for this state. -1 to ignore.

ITMTState Set the state of ITMT flag. -1 to ignore.

IRQMigrate Migrate IRQs to the active CPUs in this state. -1 to ignore.

MinPollInterval Minimum polling interval in milli seconds.

MaxPollInterval Maximum polling interval in milli seconds. This is optional, if there is no maximum is desired.

PollIntervalIncrement Polling interval increment in milli seconds. If this value is -1, then polling increment is adaptive based on the utilization.

The configuration file format conforms to XML specifications.

<Configuration>
	<!--
		CPU format example: 1,2,4..6,8-10
	-->
	<lp_mode_cpus>Example CPUs</lp_mode_cpus>

	<!--
		Mode values
		0: Cgroup v2
		1: Cgroup v2 isolate
		2: CPU idle injection
	-->
	<Mode>0|1|2</Mode>

	<!--
		Default behavior when Performance power setting is used
		-1: force off. (Never enter Low Power Mode)
		 1: force on. (Always stay in Low Power Mode)
		 0: auto. (opportunistic Low Power Mode enter/exit)
	-->
	<PerformanceDef>-1|0|1</PerformanceDef>

	<!--
		Default behavior when Balanced power setting is used
		-1: force off. (Never enter Low Power Mode)
		 1: force on. (Always stay in Low Power Mode)
		 0: auto. (opportunistic Low Power Mode enter/exit)
	-->
	<BalancedDef>-1|0|1</BalancedDef>

	<!--
		Default behavior when Power saver setting is used
		-1: force off. (Never enter Low Power Mode)
		 1: force on. (Always stay in Low Power Mode)
		 0: auto. (opportunistic Low Power Mode enter/exit)
	-->
	<PowersaverDef>-1|0|1</PowersaverDef>

	<!--
		Use HFI LPM hints
		0 : No
		1 : Yes
	-->
	<HfiLpmEnable>0|1</HfiLpmEnable>

	<!--
		Use HFI SUV hints
		0 : No
		1 : Yes
	-->
	<HfiSuvEnable>0|1</HfiSuvEnable>

	<!--
		System utilization threshold to enter LP mode
		from 0 - 100
	-->
	<util_entry_threshold>Example threshold</util_entry_threshold>

	<!--
		System utilization threshold to exit LP mode
		from 0 - 100
	-->
	<util_exit_threshold>Example threshold</util_exit_threshold>

	<!--
		Entry delay. Minimum delay in non Low Power mode to
		enter LPM mode.
	-->
	<EntryDelayMS>Example delay</EntryDelayMS>

	<!--
		Exit delay. Minimum delay in Low Power mode to
		exit LPM mode.
	-->
	<ExitDelayMS>Example delay</ExitDelayMS>

	<!--
		Lowest hyst average in-LP-mode time in msec to enter LP mode
		0: to disable hyst support
	-->
	<EntryHystMS>Example hyst</EntryHystMS>

	<!--
		Lowest hyst average out-of-LP-mode time in msec to exit LP mode
		0: to disable hyst support
	-->
	<ExitHystMS>Example hyst</ExitHystMS>

	<!--
		EPP to use in Low Power Mode
		0-255: Valid EPP value to use in Low Power Mode
		   -1: Don't change EPP in Low Power Mode
	-->
	<lp_mode_epp>-1 | EPP value</lp_mode_epp>

</Configuration>

Example 1: This is the minimum configuration.

• lp_mode_cpus: not set. Detects the lp_mode_cpus automatically.
• Mode: 0. Use cgroup-v2 systemd for task migration.
• HfiLpmEnable: 0. Ignore HFI Low Power mode hints.
• HfiSuvEnable: 0. Ignore HFI Survivability mode hints. With both HfiLpmEnable and HfiSuvEnable cleared, the HFI monitor will be disabled.
• util_entry_threshold: 0. Disable utilization monitor.
• util_exit_threshold: 0. Disable utilization monitor.
• EntryDelayMS: 0. Do not take effect when utilization monitor is disabled.
• ExitDelayMS: 0. Do not take effect when utilization monitor is disabled.
• EntryHystMS: 0. Do not take effect when utilization monitor is disabled.
• ExitHystMS: 0. Do not take effect when utilization monitor is disabled.

• lp_mode_epp: -1. Do not change EPP when entering Low Power Mode.

  <?xml version="1.0"?>
  <Configuration>
  	<lp_mode_cpus></lp_mode_cpus>
  	<Mode>0</Mode>
  	<HfiLpmEnable>0</HfiLpmEnable>
  	<HfiSuvEnable>0</HfiSuvEnable>
  	<util_entry_threshold>0</util_entry_threshold>
  	<util_exit_threshold>0</util_exit_threshold>
  	<EntryDelayMS>0</EntryDelayMS>
  	<ExitDelayMS>0</ExitDelayMS>
  	<EntryHystMS>0</EntryHystMS>
  	<ExitHystMS>0</ExitHystMS>
  	<lp_mode_epp>-1</lp_mode_epp>
  </Configuration>
  
  Example 2:
  This is the typical configuration. The utilization thresholds and delays may be different based on requirement.
  ·
      lp_mode_cpus: not set. Detects the lp_mode_cpus automatically.
      ·
      Mode: 0. Use cgroup-v2 systemd for task migration.
      ·
      HfiLpmEnable: 1. Enter/Exit Low Power Mode based on HFI hints.
      ·
      HfiSuvEnable: 1. Enter/Exit Survivability mode based on HFI hints.
      ·
      util_entry_threshold: 5. Enter Low Power Mode when system utilization is lower than 5%.
      ·
      util_exit_threshold: 95. Exit Low Power Mode when the utilization of any of the lp_mode_cpus is higher than 95%.
      ·
      EntryDelayMS: 0. Resample every 1000ms when system is out of Low Power Mode.
      ·
      ExitDelayMS: 0. Resample adaptively based on the utilization of lp_mode_cpus when system is in Low Power Mode.
      ·
      EntryHystMS: 2000. Ignore the current Enter Low Power Mode request when the previous average time stayed in Low Power Mode is lower than 2000ms.
      ·
      ExitHystMS: 3000. Ignore the current Exit Low Power Mode request when the previous average time stayed out of Low Power Mode is lower than 3000ms.
      ·
      lp_mode_epp: -1. Do not change EPP when entering Low Power Mode.
  
  
  <?xml version="1.0"?>
  <Configuration>
  	<lp_mode_cpus></lp_mode_cpus>
  	<Mode>0</Mode>
  	<HfiLpmEnable>1</HfiLpmEnable>
  	<HfiSuvEnable>1</HfiSuvEnable>
  	<util_entry_threshold>5</util_entry_threshold>
  	<util_exit_threshold>95</util_exit_threshold>
  	<EntryDelayMS>0</EntryDelayMS>
  	<ExitDelayMS>0</ExitDelayMS>
  	<EntryHystMS>2000</EntryHystMS>
  	<ExitHystMS>3000</ExitHystMS>
  	<lp_mode_epp>-1</lp_mode_epp>
  </Configuration>

intel_lpmd(8).