1 .TH CPUPOWER\-SET "1" "22/02/2011" "" "cpupowe 1 .TH CPUPOWER\-SET "1" "22/02/2011" "" "cpupower Manual"
2 .SH NAME 2 .SH NAME
3 cpupower\-set \- Set processor power related k 3 cpupower\-set \- Set processor power related kernel or hardware configurations
4 .SH SYNOPSIS 4 .SH SYNOPSIS
5 .ft B 5 .ft B
6 .B cpupower set [ \-b VAL ] 6 .B cpupower set [ \-b VAL ]
7 7
8 8
9 .SH DESCRIPTION 9 .SH DESCRIPTION
10 \fBcpupower set \fP sets kernel configurations 10 \fBcpupower set \fP sets kernel configurations or directly accesses hardware
11 registers affecting processor power saving pol 11 registers affecting processor power saving policies.
12 12
13 Some options are platform wide, some affect si 13 Some options are platform wide, some affect single cores. By default values
14 are applied on all cores. How to modify single 14 are applied on all cores. How to modify single core configurations is
15 described in the cpupower(1) manpage in the \- 15 described in the cpupower(1) manpage in the \-\-cpu option section. Whether an
16 option affects the whole system or can be appl 16 option affects the whole system or can be applied to individual cores is
17 described in the Options sections. 17 described in the Options sections.
18 18
19 Use \fBcpupower info \fP to read out current s 19 Use \fBcpupower info \fP to read out current settings and whether they are
20 supported on the system at all. 20 supported on the system at all.
21 21
22 .SH Options 22 .SH Options
23 .PP 23 .PP
24 \-\-perf-bias, \-b 24 \-\-perf-bias, \-b
25 .RS 4 25 .RS 4
26 Sets a register on supported Intel processore 26 Sets a register on supported Intel processore which allows software to convey
27 its policy for the relative importance of perf 27 its policy for the relative importance of performance versus energy savings to
28 the processor. 28 the processor.
29 29
30 The range of valid numbers is 0-15, where 0 is 30 The range of valid numbers is 0-15, where 0 is maximum
31 performance and 15 is maximum energy efficienc 31 performance and 15 is maximum energy efficiency.
32 32
33 The processor uses this information in model-s 33 The processor uses this information in model-specific ways
34 when it must select trade-offs between perform 34 when it must select trade-offs between performance and
35 energy efficiency. 35 energy efficiency.
36 36
37 This policy hint does not supersede Processor 37 This policy hint does not supersede Processor Performance states
38 (P-states) or CPU Idle power states (C-states) 38 (P-states) or CPU Idle power states (C-states), but allows
39 software to have influence where it would othe 39 software to have influence where it would otherwise be unable
40 to express a preference. 40 to express a preference.
41 41
42 For example, this setting may tell the hardwar 42 For example, this setting may tell the hardware how
43 aggressively or conservatively to control freq 43 aggressively or conservatively to control frequency
44 in the "turbo range" above the explicitly OS-c 44 in the "turbo range" above the explicitly OS-controlled
45 P-state frequency range. It may also tell the 45 P-state frequency range. It may also tell the hardware
46 how aggressively it should enter the OS reques 46 how aggressively it should enter the OS requested C-states.
47 47
48 This option can be applied to individual cores 48 This option can be applied to individual cores only via the \-\-cpu option,
49 cpupower(1). 49 cpupower(1).
50 50
51 Setting the performance bias value on one CPU 51 Setting the performance bias value on one CPU can modify the setting on
52 related CPUs as well (for example all CPUs on 52 related CPUs as well (for example all CPUs on one socket), because of
53 hardware restrictions. 53 hardware restrictions.
54 Use \fBcpupower -c all info -b\fP to verify. 54 Use \fBcpupower -c all info -b\fP to verify.
55 55
56 This options needs the msr kernel driver (CONF 56 This options needs the msr kernel driver (CONFIG_X86_MSR) loaded.
57 .RE 57 .RE
58 58
59 .SH "SEE ALSO" 59 .SH "SEE ALSO"
60 cpupower-info(1), cpupower-monitor(1), powerto 60 cpupower-info(1), cpupower-monitor(1), powertop(1)
61 .PP 61 .PP
62 .SH AUTHORS 62 .SH AUTHORS
63 .nf 63 .nf
64 \-\-perf\-bias parts written by Len Brown <len. 64 \-\-perf\-bias parts written by Len Brown <len.brown@intel.com>
65 Thomas Renninger <trenn@suse.de> 65 Thomas Renninger <trenn@suse.de>
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