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| author | Christian Loehle <christian.loehle@arm.com> | 2024-10-18 01:00:33 +0300 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2024-10-21 14:20:03 +0300 |
| commit | 29dcbea92460e82181774b46f08b55a917615a97 (patch) | |
| tree | 316baee366b6f82f8b1e8e55f0966194b8e956a9 /Documentation | |
| parent | 42f7652d3eb527d03665b09edac47f85fb600924 (diff) | |
| download | linux-29dcbea92460e82181774b46f08b55a917615a97.tar.xz | |
cpufreq: docs: Reflect latency changes in docs
There were two changes related to transition latency recently.
Namely commit e13aa799c2a6 ("cpufreq: Change default transition delay
to 2ms") and
commit 37c6dccd6837 ("cpufreq: Remove LATENCY_MULTIPLIER").
Both changed the defaults / maximums so let the documentation
reflect that.
Signed-off-by: Christian Loehle <christian.loehle@arm.com>
Link: https://patch.msgid.link/46853b6e-bad5-4ace-9b23-ff157f234ae3@arm.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/pm/cpufreq.rst | 20 |
1 files changed, 10 insertions, 10 deletions
diff --git a/Documentation/admin-guide/pm/cpufreq.rst b/Documentation/admin-guide/pm/cpufreq.rst index fe1be4ad88cb..a21369eba034 100644 --- a/Documentation/admin-guide/pm/cpufreq.rst +++ b/Documentation/admin-guide/pm/cpufreq.rst @@ -425,8 +425,8 @@ This governor exposes only one tunable: ``rate_limit_us`` Minimum time (in microseconds) that has to pass between two consecutive - runs of governor computations (default: 1000 times the scaling driver's - transition latency). + runs of governor computations (default: 1.5 times the scaling driver's + transition latency or the maximum 2ms). The purpose of this tunable is to reduce the scheduler context overhead of the governor which might be excessive without it. @@ -474,17 +474,17 @@ This governor exposes the following tunables: This is how often the governor's worker routine should run, in microseconds. - Typically, it is set to values of the order of 10000 (10 ms). Its - default value is equal to the value of ``cpuinfo_transition_latency`` - for each policy this governor is attached to (but since the unit here - is greater by 1000, this means that the time represented by - ``sampling_rate`` is 1000 times greater than the transition latency by - default). + Typically, it is set to values of the order of 2000 (2 ms). Its + default value is to add a 50% breathing room + to ``cpuinfo_transition_latency`` on each policy this governor is + attached to. The minimum is typically the length of two scheduler + ticks. If this tunable is per-policy, the following shell command sets the time - represented by it to be 750 times as high as the transition latency:: + represented by it to be 1.5 times as high as the transition latency + (the default):: - # echo `$(($(cat cpuinfo_transition_latency) * 750 / 1000)) > ondemand/sampling_rate + # echo `$(($(cat cpuinfo_transition_latency) * 3 / 2)) > ondemand/sampling_rate ``up_threshold`` If the estimated CPU load is above this value (in percent), the governor |