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Diffstat (limited to 'Documentation/cpu-freq/user-guide.txt')
| -rw-r--r-- | Documentation/cpu-freq/user-guide.txt | 60 |
1 files changed, 32 insertions, 28 deletions
diff --git a/Documentation/cpu-freq/user-guide.txt b/Documentation/cpu-freq/user-guide.txt index 109e97bbab77..107f6fdd7d14 100644 --- a/Documentation/cpu-freq/user-guide.txt +++ b/Documentation/cpu-freq/user-guide.txt @@ -18,7 +18,7 @@ Contents: --------- 1. Supported Architectures and Processors -1.1 ARM +1.1 ARM and ARM64 1.2 x86 1.3 sparc64 1.4 ppc @@ -37,16 +37,10 @@ Contents: 1. Supported Architectures and Processors ========================================= -1.1 ARM -------- - -The following ARM processors are supported by cpufreq: - -ARM Integrator -ARM-SA1100 -ARM-SA1110 -Intel PXA +1.1 ARM and ARM64 +----------------- +Almost all ARM and ARM64 platforms support CPU frequency scaling. 1.2 x86 ------- @@ -69,6 +63,7 @@ Transmeta Crusoe Transmeta Efficeon VIA Cyrix 3 / C3 various processors on some ACPI 2.0-compatible systems [*] +And many more [*] Only if "ACPI Processor Performance States" are available to the ACPI<->BIOS interface. @@ -147,10 +142,19 @@ mounted it at /sys, the cpufreq interface is located in a subdirectory "cpufreq" within the cpu-device directory (e.g. /sys/devices/system/cpu/cpu0/cpufreq/ for the first CPU). +affected_cpus : List of Online CPUs that require software + coordination of frequency. + +cpuinfo_cur_freq : Current frequency of the CPU as obtained from + the hardware, in KHz. This is the frequency + the CPU actually runs at. + cpuinfo_min_freq : this file shows the minimum operating frequency the processor can run at(in kHz) + cpuinfo_max_freq : this file shows the maximum operating frequency the processor can run at(in kHz) + cpuinfo_transition_latency The time it takes on this CPU to switch between two frequencies in nano seconds. If unknown or known to be @@ -163,25 +167,30 @@ cpuinfo_transition_latency The time it takes on this CPU to userspace daemon. Make sure to not switch the frequency too often resulting in performance loss. -scaling_driver : this file shows what cpufreq driver is - used to set the frequency on this CPU + +related_cpus : List of Online + Offline CPUs that need software + coordination of frequency. + +scaling_available_frequencies : List of available frequencies, in KHz. scaling_available_governors : this file shows the CPUfreq governors available in this kernel. You can see the currently activated governor in +scaling_cur_freq : Current frequency of the CPU as determined by + the governor and cpufreq core, in KHz. This is + the frequency the kernel thinks the CPU runs + at. + +scaling_driver : this file shows what cpufreq driver is + used to set the frequency on this CPU + scaling_governor, and by "echoing" the name of another governor you can change it. Please note that some governors won't load - they only work on some specific architectures or processors. -cpuinfo_cur_freq : Current frequency of the CPU as obtained from - the hardware, in KHz. This is the frequency - the CPU actually runs at. - -scaling_available_frequencies : List of available frequencies, in KHz. - scaling_min_freq and scaling_max_freq show the current "policy limits" (in kHz). By echoing new values into these @@ -190,16 +199,11 @@ scaling_max_freq show the current "policy limits" (in first set scaling_max_freq, then scaling_min_freq. -affected_cpus : List of Online CPUs that require software - coordination of frequency. - -related_cpus : List of Online + Offline CPUs that need software - coordination of frequency. - -scaling_cur_freq : Current frequency of the CPU as determined by - the governor and cpufreq core, in KHz. This is - the frequency the kernel thinks the CPU runs - at. +scaling_setspeed This can be read to get the currently programmed + value by the governor. This can be written to + change the current frequency for a group of + CPUs, represented by a policy. This is supported + currently only by the userspace governor. bios_limit : If the BIOS tells the OS to limit a CPU to lower frequencies, the user can read out the |