Manual: cpupower-monitor

CPUPOWER-MONITOR(1)				       cpupower Manual					 CPUPOWER-MONITOR(1)

NAME
       cpupower-monitor - Report processor frequency and idle statistics

SYNOPSIS
       cpupower monitor -l

       cpupower monitor [-c][-m ,[,...]]  [-i seconds]
       cpupower monitor [-c][-m ,[,...]]  command

DESCRIPTION
       cpupower-monitor	 reports processor topology, frequency and idle power state statistics. Either command is forked and
       statistics are printed upon its completion, or statistics are printed periodically.

       cpupower-monitor	 implements independent processor sleep state and frequency counters. Some are retrieved from kernel
       statistics,  some  are directly reading out hardware registers. Use -l to get an overview which are supported on your
       system.

Options
       -l
	   List available monitors on your system. Additional details about each monitor are shown:

	     •	    The name in quotation marks which can be passed to the -m parameter.

	     •	    The number of different counters the monitor supports in brackets.

	     •	    The amount of time in seconds the counters might overflow, due to implementation constraints.

	     •	    The name and a description of each counter and its processor hierarchy level coverage in  square  brack‐
		    ets:

		 •	[T] -> Thread

		 •	[C] -> Core

		 •	[P] -> Processor Package (Socket)

		 •	[M] -> Machine/Platform wide counter

       -m ,,...
	   Only display specific monitors. Use the monitor string(s) provided by -l option.

       -i seconds
	   Measure interval.

       -c
	   Schedule the process on every core before starting and ending measuring.  This could be needed for the Idle_Stats
	   monitor when no other MSR based monitor (has to be run on the core that is measured) is run in parallel.  This is
	   to  wake up the processors from deeper sleep states and let the kernel re -account its cpuidle (C-state) informa‐
	   tion before reading the cpuidle timings from sysfs.

       command
	   Measure idle and frequency characteristics of an arbitrary command/workload.	 The executable	 command  is  forked
	   and upon its exit, statistics gathered since it was forked are displayed.

MONITOR DESCRIPTIONS
   Idle_Stats
       Shows  statistics  of  the  cpuidle  kernel  subsystem.	Values are retrieved from /sys/devices/system/cpu/cpu*/cpui‐
       dle/state*/.  The kernel updates these values every time an idle state is entered or left.  Therefore  there  can  be
       some  inaccuracy	 when cores are in an idle state for some time when the measure starts or ends. In worst case it can
       happen that one core stayed in an idle state for the whole measure time and the idle state usage time as exported  by
       the kernel did not get updated. In this case a state residency of 0 percent is shown while it was 100.

   Mperf
       The  name  comes	 from  the  aperf/mperf	 (average  and maximum) MSR registers used which are available on recent X86
       processors. It shows the average frequency (including boost frequencies).  The fact that on all recent  hardware	 the
       mperf  timer stops ticking in any idle state it is also used to show C0 (processor is active) and Cx (processor is in
       any sleep state) times. These counters do not have the inaccuracy restrictions the "Idle_Stats"	counters  may  show.
       May  work  poorly  on  Linux-2.6.20  through 2.6.29, as the acpi-cpufreq kernel frequency driver periodically cleared
       aperf/mperf registers in those kernels.

   Nehalem SandyBridge HaswellExtended
       Intel Core and Package sleep state counters.  Threads (hyperthreaded cores) may not be  able  to	 enter	deeper	core
       states  if  its	sibling	 is  utilized.	Deepest package sleep states may in reality show up as machine/platform wide
       sleep states and can only be entered if all cores are idle. Look up Intel manuals (some are provided  in	 the  Refer‐
       ences  section)	for further details.  The monitors are named after the CPU family where the sleep state capabilities
       got introduced and may not match exactly the CPU name of the platform.  For example an IvyBridge processor has  sleep
       state  capabilities which got introduced in Nehalem and SandyBridge processor families.	Thus on an IvyBridge proces‐
       sor one will get Nehalem and SandyBridge sleep state monitors.  HaswellExtended extra package sleep  state  capabili‐
       ties are available only in a specific Haswell (family 0x45) and probably also other future processors.

   Fam_12h Fam_14h
       AMD  laptop  and desktop processor (family 12h and 14h) sleep state counters.  The registers are accessed via PCI and
       therefore can still be read out while cores have been offlined.

       There is one special counter: NBP1 (North Bridge P1).  This one always returns 0 or 1, depending on whether the North
       Bridge P1 power state got entered at least once during measure time.  Being able to enter NBP1 state also depends  on
       graphics	 power	management.  Therefore this counter can be used to verify whether the graphics' driver power manage‐
       ment is working as expected.

EXAMPLES
       cpupower monitor -l" may show:
	   Monitor "Mperf" (3 states) - Might overflow after 922000000 s

	      ...

	   Monitor "Idle_Stats" (3 states) - Might overflow after 4294967295 s

	      ...

       cpupower monitor -m "Idle_Stats,Mperf" scp /tmp/test /nfs/tmp

       Monitor the scp command, show both Mperf and Idle_Stats states counter statistics, but in exchanged order.

       Be careful that the typical command to fully utilize one CPU by doing:

       cpupower monitor cat /dev/zero >/dev/null

       Does not work as expected, because the measured output is redirected to /dev/null. This	could  get  workarounded  by
       putting	the line into an own, tiny shell script. Hit CTRL-c to terminate the command and get the measure output dis‐
       played.

REFERENCES
       "BIOS and Kernel Developer’s Guide (BKDG) for AMD Family 14h  Processors"  https://support.amd.com/us/Processor_Tech‐
       Docs/43170.pdf

       "What Is Intel® Turbo Boost Technology?"	 https://www.intel.com/content/www/us/en/gaming/resources/turbo-boost.html

       "Power Management - Technology Overview" https://cdrdv2.intel.com/v1/dl/getContent/637748

       "Intel®	64  and IA-32 Architectures Software Developer's Manual Volume 3B: System Programming Guide" https://www.in‐
       tel.com/products/processor/manuals

FILES
       /dev/cpu/*/msr
       /sys/devices/system/cpu/cpu*/cpuidle/state*/.

SEE ALSO
       powertop(8), msr(4), vmstat(8)

AUTHORS
       Written by Thomas Renninger 

       Nehalem, SandyBridge monitors and command passing
       based on turbostat.8 from Len Brown 

							 22/02/2011					 CPUPOWER-MONITOR(1)