path: root/include/linux/sched
diff options
authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2020-12-14 21:08:00 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2020-12-15 19:24:18 +0100
commitee2cc4276ba4909438f5894a218877660e1536d9 (patch)
tree691fe7a3348b9a8f343d50408cf2a39645abd943 /include/linux/sched
parentca6827de4b67367e73fdf43d2ea0a0064423edfb (diff)
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/sched')
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/sched/cpufreq.h b/include/linux/sched/cpufreq.h
index 3ed5aa18593f..6205578ab6ee 100644
--- a/include/linux/sched/cpufreq.h
+++ b/include/linux/sched/cpufreq.h
@@ -28,6 +28,11 @@ static inline unsigned long map_util_freq(unsigned long util,
return (freq + (freq >> 2)) * util / cap;
+static inline unsigned long map_util_perf(unsigned long util)
+ return util + (util >> 2);
#endif /* CONFIG_CPU_FREQ */