ee2cc4276b
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>
39 lines
999 B
C
39 lines
999 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_SCHED_CPUFREQ_H
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#define _LINUX_SCHED_CPUFREQ_H
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#include <linux/types.h>
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/*
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* Interface between cpufreq drivers and the scheduler:
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*/
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#define SCHED_CPUFREQ_IOWAIT (1U << 0)
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#ifdef CONFIG_CPU_FREQ
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struct cpufreq_policy;
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struct update_util_data {
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void (*func)(struct update_util_data *data, u64 time, unsigned int flags);
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};
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void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data,
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void (*func)(struct update_util_data *data, u64 time,
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unsigned int flags));
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void cpufreq_remove_update_util_hook(int cpu);
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bool cpufreq_this_cpu_can_update(struct cpufreq_policy *policy);
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static inline unsigned long map_util_freq(unsigned long util,
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unsigned long freq, unsigned long cap)
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{
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return (freq + (freq >> 2)) * util / cap;
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}
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static inline unsigned long map_util_perf(unsigned long util)
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{
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return util + (util >> 2);
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}
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#endif /* CONFIG_CPU_FREQ */
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#endif /* _LINUX_SCHED_CPUFREQ_H */
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