x86_energy_perf_policy(sitemap-A_de.html) - phpMan

X86_ENERGY_PERF_POLICY(8)   System Manager's Manual  X86_ENERGY_PERF_POLICY(8)

NAME
       x86_energy_perf_policy - read or write MSR_IA32_ENERGY_PERF_BIAS
SYNOPSIS
       x86_energy_perf_policy [-c cpu] [-v] -r
       x86_energy_perf_policy [-c cpu] [-v] 'performance'
       x86_energy_perf_policy [-c cpu] [-v] 'normal'
       x86_energy_perf_policy [-c cpu] [-v] 'powersave'
       x86_energy_perf_policy [-c cpu] [-v] n
DESCRIPTION
       x86_energy_perf_policy  allows  software  to  convey its policy for the
       relative importance of performance versus energy savings to the proces-
       sor.
       The processor uses this information in model-specific ways when it must
       select trade-offs between performance and energy efficiency.
       This policy hint does not supersede Processor  Performance  states  (P-
       states)  or  CPU  Idle  power states (C-states), but allows software to
       have influence where it would otherwise be unable to express a  prefer-
       ence.
       For  example,  this  setting  may tell the hardware how aggressively or
       conservatively to control frequency in  the  "turbo  range"  above  the
       explicitly OS-controlled P-state frequency range.  It may also tell the
       hardware how aggressively is should enter the OS requested C-states.
       Support for this feature is indicated  by  CPUID.06H.ECX.bit3  per  the
       Intel Architectures Software Developer's Manual.

   Options
       -c  limits operation to a single CPU.  The default is to operate on all
       CPUs.  Note that MSR_IA32_ENERGY_PERF_BIAS is defined per logical  pro-
       cessor,  but  that  the  initial implementations of the MSR were shared
       among all processors in each package.
       -v increases verbosity.  By default x86_energy_perf_policy is silent.
       -r is for "read-only" mode - the unchanged state is read and displayed.
       performance Set a policy where performance is paramount.  The processor
       will  be  unwilling to sacrifice any performance for the sake of energy
       saving. This is the hardware default.
       normal Set a policy with  a  normal  balance  between  performance  and
       energy  efficiency.  The processor will tolerate minor performance com-
       promise for potentially significant energy  savings.   This  reasonable
       default for most desktops and servers.
       powersave Set a policy where the processor can accept a measurable per-
       formance hit to maximize energy efficiency.
       n Set MSR_IA32_ENERGY_PERF_BIAS to the specified number.  The range  of
       valid numbers is 0-15, where 0 is maximum performance and 15 is maximum
       energy efficiency.

NOTES
       x86_energy_perf_policy runs only as root.
FILES
       /dev/cpu/*/msr

SEE ALSO
       msr(4)
AUTHORS
       Written by Len Brown <len.brown AT intel.com>

                                                     X86_ENERGY_PERF_POLICY(8)