Each governor is suitable for different kernel configurations: the menu governor suits better for a tickless system, while the ladder governor fits better for a periodic timer tick system.
The Kconfig does not allow to [un]select a governor, thus both are compiled in the kernel but the init order makes the menu governor to be the last one to be registered, so becoming the default. The only way to switch back to the ladder governor is to enable the sysfs governor switch in the kernel command line.
Because it seems nobody complained about this, the menu governor is used by default most of the time on the system, having both governors is not really necessary on a tickless system but there isn't a config option to disable one or another governor.
Create a submenu for cpuidle and add a label for each governor, so we can see the option in the menu config and enable/disable it.
The governors will be enabled depending on the CONFIG_NO_HZ option: - If CONFIG_NO_HZ is set, then the menu governor is selected and the ladder governor is optional, defaulting to 'no' - If CONFIG_NO_HZ is not set, then the ladder governor is selected and the menu governor is optional, defaulting to 'no'
Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org --- drivers/cpuidle/Kconfig | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-)
diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig index c4cc27e..90c2f39 100644 --- a/drivers/cpuidle/Kconfig +++ b/drivers/cpuidle/Kconfig @@ -1,7 +1,9 @@
-config CPU_IDLE +menuconfig CPU_IDLE bool "CPU idle PM support" default y if ACPI || PPC_PSERIES + select CPU_IDLE_GOV_LADDER if (!NO_HZ && !NO_HZ_IDLE) + select CPU_IDLE_GOV_MENU if (NO_HZ || NO_HZ_IDLE) help CPU idle is a generic framework for supporting software-controlled idle processor power management. It includes modular cross-platform @@ -9,9 +11,10 @@ config CPU_IDLE
If you're using an ACPI-enabled platform, you should say Y here.
+if CPU_IDLE + config CPU_IDLE_MULTIPLE_DRIVERS bool "Support multiple cpuidle drivers" - depends on CPU_IDLE default n help Allows the cpuidle framework to use different drivers for each CPU. @@ -19,24 +22,19 @@ config CPU_IDLE_MULTIPLE_DRIVERS states. If unsure say N.
config CPU_IDLE_GOV_LADDER - bool - depends on CPU_IDLE - default y + bool "Ladder governor (for periodic timer tick)" + default n if (NO_HZ || NO_HZ_IDLE)
config CPU_IDLE_GOV_MENU - bool - depends on CPU_IDLE && NO_HZ - default y + bool "Menu governor (for tickless system)" + default n if (!NO_HZ && !NO_HZ_IDLE)
config ARCH_NEEDS_CPU_IDLE_COUPLED def_bool n
-if CPU_IDLE - config CPU_IDLE_CALXEDA bool "CPU Idle Driver for Calxeda processors" depends on ARCH_HIGHBANK help Select this to enable cpuidle on Calxeda processors. - endif