[CPUFREQ] Add documentation for sampling_down_factor
Update cpufreq governor documentation for sampling_down_factor tunable
parameter.
Signed-off-by: Vishwanath BS <vishwanath.bs@ti.com>
Signed-off-by: Dave Jones <davej@redhat.com>
diff --git a/Documentation/cpu-freq/governors.txt b/Documentation/cpu-freq/governors.txt
index 737988f..e74d0a2 100644
--- a/Documentation/cpu-freq/governors.txt
+++ b/Documentation/cpu-freq/governors.txt
@@ -158,6 +158,17 @@
takes to complete as you can 'nice' it and prevent it from taking part
in the deciding process of whether to increase your CPU frequency.
+sampling_down_factor: this parameter controls the rate at which the
+kernel makes a decision on when to decrease the frequency while running
+at top speed. When set to 1 (the default) decisions to reevaluate load
+are made at the same interval regardless of current clock speed. But
+when set to greater than 1 (e.g. 100) it acts as a multiplier for the
+scheduling interval for reevaluating load when the CPU is at its top
+speed due to high load. This improves performance by reducing the overhead
+of load evaluation and helping the CPU stay at its top speed when truly
+busy, rather than shifting back and forth in speed. This tunable has no
+effect on behavior at lower speeds/lower CPU loads.
+
2.5 Conservative
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