From 2d045036322c29b69c22f06530f1130338d06373 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Wed, 19 Jul 2017 15:42:41 +0530 Subject: cpufreq: governor: Drop min_sampling_rate The cpufreq core and governors aren't supposed to set a limit on how fast we want to try changing the frequency. This is currently done for the legacy governors with help of min_sampling_rate. At worst, we may end up setting the sampling rate to a value lower than the rate at which frequency can be changed and then one of the CPUs in the policy will be only changing frequency for ever. But that is something for the user to decide and there is no need to have special handling for such cases in the core. Leave it for the user to figure out. Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki --- include/linux/cpufreq.h | 2 -- 1 file changed, 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index f10a9b3761cd..02aec384cab9 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -491,9 +491,7 @@ static inline unsigned long cpufreq_scale(unsigned long old, u_int div, * For CPUs with transition latency > 10ms (mostly drivers with CPUFREQ_ETERNAL) * the ondemand governor will not work. All times here are in us (microseconds). */ -#define MIN_SAMPLING_RATE_RATIO (2) #define LATENCY_MULTIPLIER (1000) -#define MIN_LATENCY_MULTIPLIER (20) #define TRANSITION_LATENCY_LIMIT (10 * 1000 * 1000) struct cpufreq_governor { -- cgit From aa7519af450d3c62a057aece24877c34562fa25a Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Wed, 19 Jul 2017 15:42:42 +0530 Subject: cpufreq: Use transition_delay_us for legacy governors as well The policy->transition_delay_us field is used only by the schedutil governor currently, and this field describes how fast the driver wants the cpufreq governor to change CPUs frequency. It should rather be a common thing across all governors, as it doesn't have any schedutil dependency here. Create a new helper cpufreq_policy_transition_delay_us() to get the transition delay across all governors. Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki --- include/linux/cpufreq.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index 02aec384cab9..aaadfc543f63 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -523,6 +523,7 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy, unsigned int relation); unsigned int cpufreq_driver_resolve_freq(struct cpufreq_policy *policy, unsigned int target_freq); +unsigned int cpufreq_policy_transition_delay_us(struct cpufreq_policy *policy); int cpufreq_register_governor(struct cpufreq_governor *governor); void cpufreq_unregister_governor(struct cpufreq_governor *governor); -- cgit From ed4676e254630c1f00a4fc8f3821890fff7e3643 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Wed, 19 Jul 2017 15:42:46 +0530 Subject: cpufreq: Replace "max_transition_latency" with "dynamic_switching" There is no limitation in the ondemand or conservative governors which disallow the transition_latency to be greater than 10 ms. The max_transition_latency field is rather used to disallow automatic dynamic frequency switching for platforms which didn't wanted these governors to run. Replace max_transition_latency with a boolean (dynamic_switching) and check for transition_latency == CPUFREQ_ETERNAL along with that. This makes it pretty straight forward to read/understand now. Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki --- include/linux/cpufreq.h | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) (limited to 'include/linux') diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index aaadfc543f63..e141dbbb9d1c 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -487,12 +487,8 @@ static inline unsigned long cpufreq_scale(unsigned long old, u_int div, * polling frequency is 1000 times the transition latency of the processor. The * ondemand governor will work on any processor with transition latency <= 10ms, * using appropriate sampling rate. - * - * For CPUs with transition latency > 10ms (mostly drivers with CPUFREQ_ETERNAL) - * the ondemand governor will not work. All times here are in us (microseconds). */ #define LATENCY_MULTIPLIER (1000) -#define TRANSITION_LATENCY_LIMIT (10 * 1000 * 1000) struct cpufreq_governor { char name[CPUFREQ_NAME_LEN]; @@ -505,9 +501,8 @@ struct cpufreq_governor { char *buf); int (*store_setspeed) (struct cpufreq_policy *policy, unsigned int freq); - unsigned int max_transition_latency; /* HW must be able to switch to - next freq faster than this value in nano secs or we - will fallback to performance governor */ + /* For governors which change frequency dynamically by themselves */ + bool dynamic_switching; struct list_head governor_list; struct module *owner; }; -- cgit From fe829ed8ef1f3c7ac22843bd594ef2f6c4044288 Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Wed, 19 Jul 2017 15:42:48 +0530 Subject: cpufreq: Add CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING cpufreq driver flag The policy->transition_latency field is used for multiple purposes today and its not straight forward at all. This is how it is used: A. Set the correct transition_latency value. B. Set it to CPUFREQ_ETERNAL because: 1. We don't want automatic dynamic switching (with ondemand/conservative) to happen at all. 2. We don't know the transition latency. This patch handles the B.1. case in a more readable way. A new flag for the cpufreq drivers is added to disallow use of cpufreq governors which have dynamic_switching flag set. All the current cpufreq drivers which are setting transition_latency unconditionally to CPUFREQ_ETERNAL are updated to use it. They don't need to set transition_latency anymore. There shouldn't be any functional change after this patch. Signed-off-by: Viresh Kumar Reviewed-by: Dominik Brodowski Signed-off-by: Rafael J. Wysocki --- include/linux/cpufreq.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/linux') diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h index e141dbbb9d1c..5f40522ec98c 100644 --- a/include/linux/cpufreq.h +++ b/include/linux/cpufreq.h @@ -370,6 +370,12 @@ struct cpufreq_driver { */ #define CPUFREQ_NEED_INITIAL_FREQ_CHECK (1 << 5) +/* + * Set by drivers to disallow use of governors with "dynamic_switching" flag + * set. + */ +#define CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING (1 << 6) + int cpufreq_register_driver(struct cpufreq_driver *driver_data); int cpufreq_unregister_driver(struct cpufreq_driver *driver_data); -- cgit