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.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 87165f06a307..a5ce0bbeadb5 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -120,6 +120,13 @@ 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		transition_delay_us;
+
 	 /* Cached frequency lookup from cpufreq_driver_resolve_freq. */
 	unsigned int cached_target_freq;
 	int cached_resolved_idx;