From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Add cpuidle.governor= command line parameter to allow the default cpuidle governor to be replaced. That is useful, for example, if someone running a tickful kernel wants to use the menu governor on it. Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> --- On top of https://patchwork.kernel.org/patch/10714995/ and https://patchwork.kernel.org/patch/10705317/ --- Documentation/admin-guide/kernel-parameters.txt | 3 +++ Documentation/admin-guide/pm/cpuidle.rst | 7 +++++++ drivers/cpuidle/cpuidle.c | 1 + drivers/cpuidle/cpuidle.h | 1 + drivers/cpuidle/governor.c | 9 +++++++-- 5 files changed, 19 insertions(+), 2 deletions(-) Index: linux-pm/drivers/cpuidle/governor.c =================================================================== --- linux-pm.orig/drivers/cpuidle/governor.c +++ linux-pm/drivers/cpuidle/governor.c @@ -11,10 +11,13 @@ #include <linux/cpu.h> #include <linux/cpuidle.h> #include <linux/mutex.h> +#include <linux/module.h> #include <linux/pm_qos.h> #include "cpuidle.h" +char param_governor[CPUIDLE_NAME_LEN]; + LIST_HEAD(cpuidle_governors); struct cpuidle_governor *cpuidle_curr_governor; @@ -86,9 +89,11 @@ int cpuidle_register_governor(struct cpu mutex_lock(&cpuidle_lock); if (__cpuidle_find_governor(gov->name) == NULL) { ret = 0; - list_add_tail(&gov->governor_list, &cpuidle_governors); if (!cpuidle_curr_governor || - cpuidle_curr_governor->rating < gov->rating) + !strncasecmp(param_governor, gov->name, CPUIDLE_NAME_LEN) || + (cpuidle_curr_governor->rating < gov->rating && + strncasecmp(param_governor, cpuidle_curr_governor->name, + CPUIDLE_NAME_LEN))) cpuidle_switch_governor(gov); } mutex_unlock(&cpuidle_lock); Index: linux-pm/drivers/cpuidle/cpuidle.c =================================================================== --- linux-pm.orig/drivers/cpuidle/cpuidle.c +++ linux-pm/drivers/cpuidle/cpuidle.c @@ -731,4 +731,5 @@ static int __init cpuidle_init(void) } module_param(off, int, 0444); +module_param_string(governor, param_governor, CPUIDLE_NAME_LEN, 0444); core_initcall(cpuidle_init); Index: linux-pm/drivers/cpuidle/cpuidle.h =================================================================== --- linux-pm.orig/drivers/cpuidle/cpuidle.h +++ linux-pm/drivers/cpuidle/cpuidle.h @@ -7,6 +7,7 @@ #define __DRIVER_CPUIDLE_H /* For internal use only */ +extern char param_governor[]; extern struct cpuidle_governor *cpuidle_curr_governor; extern struct list_head cpuidle_governors; extern struct list_head cpuidle_detected_devices; Index: linux-pm/Documentation/admin-guide/pm/cpuidle.rst =================================================================== --- linux-pm.orig/Documentation/admin-guide/pm/cpuidle.rst +++ linux-pm/Documentation/admin-guide/pm/cpuidle.rst @@ -576,6 +576,13 @@ processors implementing the architecture however, so it is rather crude and not very energy-efficient. For this reason, it is not recommended for production use. +The ``cpuidle.governor=`` kernel command line switch allows the ``CPUIdle`` +governor to use to be specified. It has to be appended with a string matching +the name of an available governor (e.g. ``cpuidle.governor=menu``) and that +governor will be used instead of the default one. It is possible to force +the ``menu`` governor to be used on the systems that use the ``ladder`` governor +by default this way, for example. + The other kernel command line parameters controlling CPU idle time management described below are only relevant for the *x86* architecture and some of them affect Intel processors only. Index: linux-pm/Documentation/admin-guide/kernel-parameters.txt =================================================================== --- linux-pm.orig/Documentation/admin-guide/kernel-parameters.txt +++ linux-pm/Documentation/admin-guide/kernel-parameters.txt @@ -674,6 +674,9 @@ cpuidle.off=1 [CPU_IDLE] disable the cpuidle sub-system + cpuidle.governor= + [CPU_IDLE] Name of the cpuidle governor to use. + cpufreq.off=1 [CPU_FREQ] disable the cpufreq sub-system
