BACKPORT: cpufreq: schedutil: Use policy-dependent transition delays

Make the schedutil governor take the initial (default) value of the
rate_limit_us sysfs attribute from the (new) transition_delay_us
policy parameter (to be set by the scaling driver).

That will allow scaling drivers to make schedutil use smaller default
values of rate_limit_us and reduce the default average time interval
between consecutive frequency changes.

Make intel_pstate set transition_delay_us to 500.

BACKPORT: Modified to support the separate up_rate_limit_us and
down_rate_limit_us (upstream just has a single rate_limit_us). Also
dropped the changes for intel_pstate as there's a merge conflict.

Change-Id: I62a8543879a4d8582cdcb31ebd55607705d1c8b1
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
(cherry picked from commit 1b72e7fd304639f1cd49d1e11955c4974936d88c)
Signed-off-by: Brendan Jackman <brendan.jackman@arm.com>

diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index cc57986..0b98599 100644 (file)
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -120,6 +120,14 @@ struct cpufreq_policy {
        bool                    fast_switch_possible;
        bool                    fast_switch_enabled;
 
+       /*
+        * Preferred average time interval between consecutive invocations of
+        * the driver to set the frequency for this policy.  To be set by the
+        * scaling driver (0, which is the default, means no preference).
+        */
+       unsigned int            up_transition_delay_us;
+       unsigned int            down_transition_delay_us;
+
         /* Cached frequency lookup from cpufreq_driver_resolve_freq. */
        unsigned int cached_target_freq;
        int cached_resolved_idx;

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 1260561..43c4e45 100644 (file)
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -587,7 +587,6 @@ static int sugov_init(struct cpufreq_policy *policy)
 {
        struct sugov_policy *sg_policy;
        struct sugov_tunables *tunables;
-       unsigned int lat;
        int ret = 0;
 
        /* State should be equivalent to EXIT */
@@ -626,12 +625,19 @@ static int sugov_init(struct cpufreq_policy *policy)
                goto stop_kthread;
        }
 
-       tunables->up_rate_limit_us = LATENCY_MULTIPLIER;
-       tunables->down_rate_limit_us = LATENCY_MULTIPLIER;
-       lat = policy->cpuinfo.transition_latency / NSEC_PER_USEC;
-       if (lat) {
-               tunables->up_rate_limit_us *= lat;
-               tunables->down_rate_limit_us *= lat;
+       if (policy->up_transition_delay_us && policy->down_transition_delay_us) {
+               tunables->up_rate_limit_us = policy->up_transition_delay_us;
+               tunables->down_rate_limit_us = policy->down_transition_delay_us;
+       } else {
+               unsigned int lat;
+
+                tunables->up_rate_limit_us = LATENCY_MULTIPLIER;
+                tunables->down_rate_limit_us = LATENCY_MULTIPLIER;
+               lat = policy->cpuinfo.transition_latency / NSEC_PER_USEC;
+               if (lat) {
+                        tunables->up_rate_limit_us *= lat;
+                        tunables->down_rate_limit_us *= lat;
+                }
        }
 
        policy->governor_data = sg_policy;