Root/
1 | config CPU_FREQ |
2 | bool "CPU Frequency scaling" |
3 | help |
4 | CPU Frequency scaling allows you to change the clock speed of |
5 | CPUs on the fly. This is a nice method to save power, because |
6 | the lower the CPU clock speed, the less power the CPU consumes. |
7 | |
8 | Note that this driver doesn't automatically change the CPU |
9 | clock speed, you need to either enable a dynamic cpufreq governor |
10 | (see below) after boot, or use a userspace tool. |
11 | |
12 | For details, take a look at <file:Documentation/cpu-freq>. |
13 | |
14 | If in doubt, say N. |
15 | |
16 | if CPU_FREQ |
17 | |
18 | config CPU_FREQ_TABLE |
19 | tristate |
20 | |
21 | config CPU_FREQ_DEBUG |
22 | bool "Enable CPUfreq debugging" |
23 | help |
24 | Say Y here to enable CPUfreq subsystem (including drivers) |
25 | debugging. You will need to activate it via the kernel |
26 | command line by passing |
27 | cpufreq.debug=<value> |
28 | |
29 | To get <value>, add |
30 | 1 to activate CPUfreq core debugging, |
31 | 2 to activate CPUfreq drivers debugging, and |
32 | 4 to activate CPUfreq governor debugging |
33 | |
34 | config CPU_FREQ_STAT |
35 | tristate "CPU frequency translation statistics" |
36 | select CPU_FREQ_TABLE |
37 | default y |
38 | help |
39 | This driver exports CPU frequency statistics information through sysfs |
40 | file system. |
41 | |
42 | To compile this driver as a module, choose M here: the |
43 | module will be called cpufreq_stats. |
44 | |
45 | If in doubt, say N. |
46 | |
47 | config CPU_FREQ_STAT_DETAILS |
48 | bool "CPU frequency translation statistics details" |
49 | depends on CPU_FREQ_STAT |
50 | help |
51 | This will show detail CPU frequency translation table in sysfs file |
52 | system. |
53 | |
54 | If in doubt, say N. |
55 | |
56 | choice |
57 | prompt "Default CPUFreq governor" |
58 | default CPU_FREQ_DEFAULT_GOV_USERSPACE if CPU_FREQ_SA1100 || CPU_FREQ_SA1110 |
59 | default CPU_FREQ_DEFAULT_GOV_PERFORMANCE |
60 | help |
61 | This option sets which CPUFreq governor shall be loaded at |
62 | startup. If in doubt, select 'performance'. |
63 | |
64 | config CPU_FREQ_DEFAULT_GOV_PERFORMANCE |
65 | bool "performance" |
66 | select CPU_FREQ_GOV_PERFORMANCE |
67 | help |
68 | Use the CPUFreq governor 'performance' as default. This sets |
69 | the frequency statically to the highest frequency supported by |
70 | the CPU. |
71 | |
72 | config CPU_FREQ_DEFAULT_GOV_POWERSAVE |
73 | bool "powersave" |
74 | depends on EMBEDDED |
75 | select CPU_FREQ_GOV_POWERSAVE |
76 | help |
77 | Use the CPUFreq governor 'powersave' as default. This sets |
78 | the frequency statically to the lowest frequency supported by |
79 | the CPU. |
80 | |
81 | config CPU_FREQ_DEFAULT_GOV_USERSPACE |
82 | bool "userspace" |
83 | select CPU_FREQ_GOV_USERSPACE |
84 | help |
85 | Use the CPUFreq governor 'userspace' as default. This allows |
86 | you to set the CPU frequency manually or when a userspace |
87 | program shall be able to set the CPU dynamically without having |
88 | to enable the userspace governor manually. |
89 | |
90 | config CPU_FREQ_DEFAULT_GOV_ONDEMAND |
91 | bool "ondemand" |
92 | select CPU_FREQ_GOV_ONDEMAND |
93 | select CPU_FREQ_GOV_PERFORMANCE |
94 | help |
95 | Use the CPUFreq governor 'ondemand' as default. This allows |
96 | you to get a full dynamic frequency capable system by simply |
97 | loading your cpufreq low-level hardware driver. |
98 | Be aware that not all cpufreq drivers support the ondemand |
99 | governor. If unsure have a look at the help section of the |
100 | driver. Fallback governor will be the performance governor. |
101 | |
102 | config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE |
103 | bool "conservative" |
104 | select CPU_FREQ_GOV_CONSERVATIVE |
105 | select CPU_FREQ_GOV_PERFORMANCE |
106 | help |
107 | Use the CPUFreq governor 'conservative' as default. This allows |
108 | you to get a full dynamic frequency capable system by simply |
109 | loading your cpufreq low-level hardware driver. |
110 | Be aware that not all cpufreq drivers support the conservative |
111 | governor. If unsure have a look at the help section of the |
112 | driver. Fallback governor will be the performance governor. |
113 | endchoice |
114 | |
115 | config CPU_FREQ_GOV_PERFORMANCE |
116 | tristate "'performance' governor" |
117 | help |
118 | This cpufreq governor sets the frequency statically to the |
119 | highest available CPU frequency. |
120 | |
121 | To compile this driver as a module, choose M here: the |
122 | module will be called cpufreq_performance. |
123 | |
124 | If in doubt, say Y. |
125 | |
126 | config CPU_FREQ_GOV_POWERSAVE |
127 | tristate "'powersave' governor" |
128 | help |
129 | This cpufreq governor sets the frequency statically to the |
130 | lowest available CPU frequency. |
131 | |
132 | To compile this driver as a module, choose M here: the |
133 | module will be called cpufreq_powersave. |
134 | |
135 | If in doubt, say Y. |
136 | |
137 | config CPU_FREQ_GOV_USERSPACE |
138 | tristate "'userspace' governor for userspace frequency scaling" |
139 | help |
140 | Enable this cpufreq governor when you either want to set the |
141 | CPU frequency manually or when a userspace program shall |
142 | be able to set the CPU dynamically, like on LART |
143 | <http://www.lartmaker.nl/>. |
144 | |
145 | To compile this driver as a module, choose M here: the |
146 | module will be called cpufreq_userspace. |
147 | |
148 | For details, take a look at <file:Documentation/cpu-freq/>. |
149 | |
150 | If in doubt, say Y. |
151 | |
152 | config CPU_FREQ_GOV_ONDEMAND |
153 | tristate "'ondemand' cpufreq policy governor" |
154 | select CPU_FREQ_TABLE |
155 | help |
156 | 'ondemand' - This driver adds a dynamic cpufreq policy governor. |
157 | The governor does a periodic polling and |
158 | changes frequency based on the CPU utilization. |
159 | The support for this governor depends on CPU capability to |
160 | do fast frequency switching (i.e, very low latency frequency |
161 | transitions). |
162 | |
163 | To compile this driver as a module, choose M here: the |
164 | module will be called cpufreq_ondemand. |
165 | |
166 | For details, take a look at linux/Documentation/cpu-freq. |
167 | |
168 | If in doubt, say N. |
169 | |
170 | config CPU_FREQ_GOV_CONSERVATIVE |
171 | tristate "'conservative' cpufreq governor" |
172 | depends on CPU_FREQ |
173 | help |
174 | 'conservative' - this driver is rather similar to the 'ondemand' |
175 | governor both in its source code and its purpose, the difference is |
176 | its optimisation for better suitability in a battery powered |
177 | environment. The frequency is gracefully increased and decreased |
178 | rather than jumping to 100% when speed is required. |
179 | |
180 | If you have a desktop machine then you should really be considering |
181 | the 'ondemand' governor instead, however if you are using a laptop, |
182 | PDA or even an AMD64 based computer (due to the unacceptable |
183 | step-by-step latency issues between the minimum and maximum frequency |
184 | transitions in the CPU) you will probably want to use this governor. |
185 | |
186 | To compile this driver as a module, choose M here: the |
187 | module will be called cpufreq_conservative. |
188 | |
189 | For details, take a look at linux/Documentation/cpu-freq. |
190 | |
191 | If in doubt, say N. |
192 | |
193 | endif # CPU_FREQ |
194 |
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