Interactive cpufreq governor.

Documentation/cpu-freq/governors.txt

@@ -28,6 +28,7 @@ Contents:
 2.3  Userspace
 2.4  Ondemand
 2.5  Conservative
+2.6  Interactive
 
 3.   The Governor Interface in the CPUfreq Core
 
@@ -162,6 +163,29 @@ governor but for the opposite direction.  For example when set to its
 default value of '20' it means that if the CPU usage needs to be below
 20% between samples to have the frequency decreased.
 
+
+2.6 Interactive
+---------------
+
+The CPUfreq governor "interactive" is designed for low latency,
+interactive workloads. This governor sets the CPU speed depending on
+usage, similar to "ondemand" and "conservative" governors. However
+there is no polling, or 'sample_rate' required to scale the CPU up.
+
+Sampling CPU load every X ms can lead to under powering the CPU
+for X ms, leading to dropped framerate, stuttering UI etc..
+
+Scaling the CPU up is done when coming out of idle, and like "ondemand"
+scaling up will always go to MAX, then step down based off of cpu load.
+
+There is only one tuneable value for this governor:
+
+min_sample_time: The ammount of time the CPU must spend (in uS)
+at the current frequency before scaling DOWN. This is done to
+more accurately determine the cpu workload and the best speed for that
+workload. The default is 50ms.
+
+
 3. The Governor Interface in the CPUfreq Core
 =============================================
 

drivers/cpufreq/Kconfig

@@ -115,6 +115,15 @@ config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
 	  Be aware that not all cpufreq drivers support the conservative
 	  governor. If unsure have a look at the help section of the
 	  driver. Fallback governor will be the performance governor.
+
+config CPU_FREQ_DEFAULT_GOV_INTERACTIVE
+	bool "interactive"
+	select CPU_FREQ_GOV_INTERACTIVE
+	help
+	  Use the 'interactive' governor as default. This gets full cpu frequency
+	  scaling for workloads that are latency sensitive, typically interactive
+	  workloads..
+
 endchoice
 
 config CPU_FREQ_GOV_PERFORMANCE
@@ -172,6 +181,13 @@ config CPU_FREQ_GOV_ONDEMAND
 
 	  If in doubt, say N.
 
+config CPU_FREQ_GOV_INTERACTIVE
+	tristate "'interactive' cpufreq policy governor"
+	help
+	  'interactive' - This driver adds a dynamic cpufreq policy governor.
+	  Designed for low latency burst workloads. Scaling it done when coming
+	  out of idle instead of polling.
+
 config CPU_FREQ_GOV_CONSERVATIVE
 	tristate "'conservative' cpufreq governor"
 	depends on CPU_FREQ

drivers/cpufreq/Makefile

@@ -9,6 +9,7 @@ obj-$(CONFIG_CPU_FREQ_GOV_POWERSAVE)	+= cpufreq_powersave.o
 obj-$(CONFIG_CPU_FREQ_GOV_USERSPACE)	+= cpufreq_userspace.o
 obj-$(CONFIG_CPU_FREQ_GOV_ONDEMAND)	+= cpufreq_ondemand.o
 obj-$(CONFIG_CPU_FREQ_GOV_CONSERVATIVE)	+= cpufreq_conservative.o
+obj-$(CONFIG_CPU_FREQ_GOV_INTERACTIVE)  += cpufreq_interactive.o
 
 # CPUfreq cross-arch helpers
 obj-$(CONFIG_CPU_FREQ_TABLE)		+= freq_table.o