| .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> |
