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- .TH CPUPOWER\-SET "1" "22/02/2011" "" "cpupower Manual"
- .SH NAME
- cpupower\-set \- Set processor power related kernel or hardware configurations
- .SH SYNOPSIS
- .ft B
- .B cpupower set [ \-b VAL ]
- .SH DESCRIPTION
- \fBcpupower set \fP sets kernel configurations or directly accesses hardware
- registers affecting processor power saving policies.
- Some options are platform wide, some affect single cores. By default values
- are applied on all cores. How to modify single core configurations is
- described in the cpupower(1) manpage in the \-\-cpu option section. Whether an
- option affects the whole system or can be applied to individual cores is
- described in the Options sections.
- Use \fBcpupower info \fP to read out current settings and whether they are
- supported on the system at all.
- .SH Options
- .PP
- \-\-perf-bias, \-b
- .RS 4
- Sets a register on supported Intel processore which allows software to convey
- its policy for the relative importance of performance versus energy savings to
- the processor.
- The range of valid numbers is 0-15, where 0 is maximum
- performance and 15 is maximum energy efficiency.
- 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 it should enter the OS requested C-states.
- This option can be applied to individual cores only via the \-\-cpu option,
- cpupower(1).
- Setting the performance bias value on one CPU can modify the setting on
- related CPUs as well (for example all CPUs on one socket), because of
- hardware restrictions.
- Use \fBcpupower -c all info -b\fP to verify.
- This options needs the msr kernel driver (CONFIG_X86_MSR) loaded.
- .RE
- .SH "SEE ALSO"
- cpupower-info(1), cpupower-monitor(1), powertop(1)
- .PP
- .SH AUTHORS
- .nf
- \-\-perf\-bias parts written by Len Brown <len.brown@intel.com>
- Thomas Renninger <trenn@suse.de>
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