NAME

       rapl-set - set RAPL configurations

SYNPOSIS

       rapl-set [OPTION]...

DESCRIPTION

       Sets Intel Running Average Power Limit (RAPL) configurations.

       Since  RAPL  does  not implement all capabilities defined in the powercap interface, only a subset of the
       options from powercap-set(1) are available.  Additionally, the -p and -z options are different.

       This software requires an Intel processor (Sandy Bridge or newer), Linux kernel 3.13  or  newer  compiled
       with CONFIG_POWERCAP and CONFIG_INTEL_RAPL enabled, and the intel_rapl kernel module to be loaded.

OPTIONS

       -h, --help
              Prints out the help screen

       -p, --package=PACKAGE
              The package number (0 by default)

       -z, --subzone=SUBZONE
              The package subzone number (none by default)

       -c, --constraint=CONSTRAINT
              The constraint number (none by default)

       The following is a zone-level argument (-z/--subzone is optional):

       -e, --z-enabled=1|0
              Enable/disable a zone

       The  following  constraint-level arguments may be used together and require -c/--constraint (-z/--subzone
       is optional):

       -l, --c-power-limit=UW
              Set constraint power limit

       -s, --c-time-window=US
              Set constraint time window

EXAMPLES

       Note that -p/--package=0 is used by default, allowing for simpler commands on single-socket systems.

       rapl-set -e 1
              Enable package 0 (implicitly), which is usually named package-0.

       rapl-set -p 0 -e 1
              Enable package 0 (explicitly).

       rapl-set -p 0 -z 1 -e 1
              Enable package 0, subzone 1, which is usually the uncore or dram subzone of  package-0,  depending
              on the system.

       rapl-set -p 0 -c 1 -l 25000000
              Set  a  power  cap  of  25  Watts  (25000000  uW) on package 0, constraint 1, which is usually the
              short_term constraint for package-0.

       rapl-set -p 1 -z 0 -c 0 -l 15000000 -s 976
              Set a power cap of 15 Watts (15000000 uW) and time  window  of  976  microseconds  on  package  1,
              subzone 0, constraint 0, which is usually the long_term (and only) constraint for the core subzone
              of package-1 (a multi-socket system).

REMARKS

       Administrative (root) privileges are usually needed to use rapl-set.

       Setting  constraint power cap and/or time limit values does not enable or disable a package/subzone - the
       -e/--z-enabled flag must be set explicitly.

       A package is a zone with constraints.  Subzones are a package's child domains, including power planes.

       Power units: microwatts (uW)
       Time units: microseconds (us)

BUGS

       The following are behavioral quirks due to the kernel interface or abnormalities in some hardware.   They
       are not bugs in rapl-set and should not be reported as such.

       The  kernel  is not guaranteed to accept power limit and time window values exactly as specified.  Values
       may be rounded due to how they are encoded in Model-Specific Registers.  This rounding error  is  usually
       small within normal operating ranges, but can be significant at the extremes.

       Some  systems  may  not  accept time window values correctly, requiring a system reboot to reset the time
       window to the default value.

       Values returned by the kernel, e.g., by rapl-info(1), sometimes lose  accuracy  from  the  actual  stored
       value  due  to integer rounding.  For example, the kernel may return a time window value of 7812 us, when
       in fact the actual stored value is 7812.5 us.  Writing back an integer value returned by the  kernel  may
       cause unexpected changes to its stored value due to these rounding problems.

       Some systems may not allow disabling package-level zones/constraints.

       It  is  possible  for  packages  on  multi-socket  systems to be indexed out of order by the kernel.  For
       example, the package at index 0 (-p 0) could actually be named package-1 while the package at index 1 (-p
       1) is named package-0.  If this matters to the user, it is their responsibility to check  before  setting
       values, e.g., using rapl-info(1).

       Report bugs upstream at <https://github.com/powercap/powercap>

FILES

       /sys/devices/virtual/powercap/intel-rapl/*
       /sys/class/powercap/intel-rapl/*

AUTHORS

       Connor Imes <connor.k.imes@gmail.com>

SEE ALSO

       rapl-info(1), powercap-info(1), powercap-set(1)

powercap                                           2017-09-20                                        rapl-set(1)