centos man page for x86_energy_perf_policy

Query: x86_energy_perf_policy

OS: centos

Section: 8

Format: Original Unix Latex Style Formatted with HTML and a Horizontal Scroll Bar

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 preference. 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 processor, 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 compro- mise for potentially significant energy savings. This reasonable default for most desktops and servers. powersave Set a policy where the processor can accept a measurable performance 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 max- imum 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@intel.com> X86_ENERGY_PERF_POLICY(8)
Related Man Pages
x86_energy_perf_policy(8) - centos
cpupower-frequency-info(1) - centos
pstatectl(1m) - hpux
offline(8) - osf1
powerd(8) - freebsd
Similar Topics in the Unix Linux Community
on hpunix cpu usage fields
AIX server performance problem!
is this an 11.31 feature? cpu sequence...
High Performance Computing
Linux machine performance issue.