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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2020-12-14 23:08:00 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2020-12-15 21:24:18 +0300
commitee2cc4276ba4909438f5894a218877660e1536d9 (patch)
tree691fe7a3348b9a8f343d50408cf2a39645abd943 /include/linux/cpufreq.h
parentca6827de4b67367e73fdf43d2ea0a0064423edfb (diff)
downloadlinux-ee2cc4276ba4909438f5894a218877660e1536d9.tar.xz
cpufreq: Add special-purpose fast-switching callback for drivers
First off, some cpufreq drivers (eg. intel_pstate) can pass hints beyond the current target frequency to the hardware and there are no provisions for doing that in the cpufreq framework. In particular, today the driver has to assume that it should not allow the frequency to fall below the one requested by the governor (or the required capacity may not be provided) which may not be the case and which may lead to excessive energy usage in some scenarios. Second, the hints passed by these drivers to the hardware need not be in terms of the frequency, so representing the utilization numbers coming from the scheduler as frequency before passing them to those drivers is not really useful. Address the two points above by adding a special-purpose replacement for the ->fast_switch callback, called ->adjust_perf, allowing the governor to pass abstract performance level (rather than frequency) values for the minimum (required) and target (desired) performance along with the CPU capacity to compare them to. Also update the schedutil governor to use the new callback instead of ->fast_switch if present and if the utilization mertics are frequency-invariant (that is requisite for the direct mapping between the utilization and the CPU performance levels to be a reasonable approximation). Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Diffstat (limited to 'include/linux/cpufreq.h')
-rw-r--r--include/linux/cpufreq.h14
1 files changed, 14 insertions, 0 deletions
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 584fccd4fcab..9c8b7437b6cd 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -320,6 +320,15 @@ struct cpufreq_driver {
unsigned int index);
unsigned int (*fast_switch)(struct cpufreq_policy *policy,
unsigned int target_freq);
+ /*
+ * ->fast_switch() replacement for drivers that use an internal
+ * representation of performance levels and can pass hints other than
+ * the target performance level to the hardware.
+ */
+ void (*adjust_perf)(unsigned int cpu,
+ unsigned long min_perf,
+ unsigned long target_perf,
+ unsigned long capacity);
/*
* Caches and returns the lowest driver-supported frequency greater than
@@ -588,6 +597,11 @@ struct cpufreq_governor {
/* Pass a target to the cpufreq driver */
unsigned int cpufreq_driver_fast_switch(struct cpufreq_policy *policy,
unsigned int target_freq);
+void cpufreq_driver_adjust_perf(unsigned int cpu,
+ unsigned long min_perf,
+ unsigned long target_perf,
+ unsigned long capacity);
+bool cpufreq_driver_has_adjust_perf(void);
int cpufreq_driver_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation);