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cpufreq: docs: Reflect latency changes in docs
There were two changes related to transition latency recently. Namely commit e13aa79 ("cpufreq: Change default transition delay to 2ms") and commit 37c6dcc ("cpufreq: Remove LATENCY_MULTIPLIER"). Both changed the defaults / maximums so let the documentation reflect that. Signed-off-by: Christian Loehle <[email protected]> Link: https://patch.msgid.link/[email protected] Signed-off-by: Rafael J. Wysocki <[email protected]>
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Documentation/admin-guide/pm/cpufreq.rst

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@@ -425,8 +425,8 @@ This governor exposes only one tunable:
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``rate_limit_us``
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Minimum time (in microseconds) that has to pass between two consecutive
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runs of governor computations (default: 1000 times the scaling driver's
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transition latency).
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runs of governor computations (default: 1.5 times the scaling driver's
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transition latency or the maximum 2ms).
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The purpose of this tunable is to reduce the scheduler context overhead
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of the governor which might be excessive without it.
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This is how often the governor's worker routine should run, in
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microseconds.
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Typically, it is set to values of the order of 10000 (10 ms). Its
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default value is equal to the value of ``cpuinfo_transition_latency``
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for each policy this governor is attached to (but since the unit here
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is greater by 1000, this means that the time represented by
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``sampling_rate`` is 1000 times greater than the transition latency by
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default).
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Typically, it is set to values of the order of 2000 (2 ms). Its
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default value is to add a 50% breathing room
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to ``cpuinfo_transition_latency`` on each policy this governor is
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attached to. The minimum is typically the length of two scheduler
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ticks.
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If this tunable is per-policy, the following shell command sets the time
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represented by it to be 750 times as high as the transition latency::
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represented by it to be 1.5 times as high as the transition latency
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(the default)::
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# echo `$(($(cat cpuinfo_transition_latency) * 750 / 1000)) > ondemand/sampling_rate
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# echo `$(($(cat cpuinfo_transition_latency) * 3 / 2)) > ondemand/sampling_rate
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``up_threshold``
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If the estimated CPU load is above this value (in percent), the governor

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