path: root/Documentation
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authorLinus Torvalds <torvalds@linux-foundation.org>2009-12-11 15:59:23 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-11 15:59:23 -0800
commit2fe77b81c77eed92c4c0439f74c8148a295b4a86 (patch)
tree8a5e33fc3804f29bbf5c95c2cd28ccbdaa4cf206 /Documentation
parentcb5228a6949f525dba37d4eb3ee114426fef22c9 (diff)
parente2f74f355e9e2914483db10c05d70e69e0b7ae04 (diff)
Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/davej/cpufreq: [ACPI/CPUFREQ] Introduce bios_limit per cpu cpufreq sysfs interface [CPUFREQ] make internal cpufreq_add_dev_* static [CPUFREQ] use an enum for speedstep processor identification [CPUFREQ] Document units for transition latency [CPUFREQ] Use global sysfs cpufreq structure for conservative governor tunings [CPUFREQ] Documentation: ABI: /sys/devices/system/cpu/cpu#/cpufreq/ [CPUFREQ] powernow-k6: set transition latency value so ondemand governor can be used [CPUFREQ] cpumask: don't put a cpumask on the stack in x86...cpufreq/powernow-k8.c
Diffstat (limited to 'Documentation')
3 files changed, 32 insertions, 3 deletions
diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index a703b9e9aeb9..974e29f5da86 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -136,6 +136,24 @@ Description: Discover cpuidle policy and mechanism
See files in Documentation/cpuidle/ for more information.
+What: /sys/devices/system/cpu/cpu#/cpufreq/*
+Date: pre-git history
+Contact: cpufreq@vger.kernel.org
+Description: Discover and change clock speed of CPUs
+ Clock scaling allows you to change the clock speed of the
+ CPUs on the fly. This is a nice method to save battery
+ power, because the lower the clock speed, the less power
+ the CPU consumes.
+ There are many knobs to tweak in this directory.
+ See files in Documentation/cpu-freq/ for more information.
+ In particular, read Documentation/cpu-freq/user-guide.txt
+ to learn how to control the knobs.
What: /sys/devices/system/cpu/cpu*/cache/index*/cache_disable_X
Date: August 2008
KernelVersion: 2.6.27
diff --git a/Documentation/cpu-freq/cpu-drivers.txt b/Documentation/cpu-freq/cpu-drivers.txt
index 75a58d14d3cf..6c30e930c122 100644
--- a/Documentation/cpu-freq/cpu-drivers.txt
+++ b/Documentation/cpu-freq/cpu-drivers.txt
@@ -92,9 +92,9 @@ policy->cpuinfo.max_freq - the minimum and maximum frequency
(in kHz) which is supported by
this CPU
policy->cpuinfo.transition_latency the time it takes on this CPU to
- switch between two frequencies (if
- appropriate, else specify
+ switch between two frequencies in
+ nanoseconds (if appropriate, else
policy->cur The current operating frequency of
this CPU (if appropriate)
diff --git a/Documentation/cpu-freq/user-guide.txt b/Documentation/cpu-freq/user-guide.txt
index 2a5b850847c0..04f6b32993e6 100644
--- a/Documentation/cpu-freq/user-guide.txt
+++ b/Documentation/cpu-freq/user-guide.txt
@@ -203,6 +203,17 @@ scaling_cur_freq : Current frequency of the CPU as determined by
the frequency the kernel thinks the CPU runs
+bios_limit : If the BIOS tells the OS to limit a CPU to
+ lower frequencies, the user can read out the
+ maximum available frequency from this file.
+ This typically can happen through (often not
+ intended) BIOS settings, restrictions
+ triggered through a service processor or other
+ BIOS/HW based implementations.
+ This does not cover thermal ACPI limitations
+ which can be detected through the generic
+ thermal driver.
If you have selected the "userspace" governor which allows you to
set the CPU operating frequency to a specific value, you can read out
the current frequency in