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Subject[PATCH v5 02/14] sched/cpufreq: Factor out utilization to frequency mapping
Date
The schedutil governor maps utilization values to frequencies by applying
a 25% margin. Since this sort of mapping mechanism can be needed by other
users (i.e. EAS), factor the utilization-to-frequency mapping code out
of schedutil and move it to include/linux/sched/cpufreq.h to avoid code
duplication. The new map_util_freq() function is inlined to avoid
overheads.

Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Quentin Perret <quentin.perret@arm.com>
---
include/linux/sched/cpufreq.h | 6 ++++++
kernel/sched/cpufreq_schedutil.c | 3 ++-
2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/include/linux/sched/cpufreq.h b/include/linux/sched/cpufreq.h
index 59667444669f..afa940cd50dc 100644
--- a/include/linux/sched/cpufreq.h
+++ b/include/linux/sched/cpufreq.h
@@ -20,6 +20,12 @@ void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data,
void (*func)(struct update_util_data *data, u64 time,
unsigned int flags));
void cpufreq_remove_update_util_hook(int cpu);
+
+static inline unsigned long map_util_freq(unsigned long util,
+ unsigned long freq, unsigned long cap)
+{
+ return (freq + (freq >> 2)) * util / cap;
+}
#endif /* CONFIG_CPU_FREQ */

#endif /* _LINUX_SCHED_CPUFREQ_H */
diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 97dcd4472a0e..810193c8e4cd 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -13,6 +13,7 @@

#include "sched.h"

+#include <linux/sched/cpufreq.h>
#include <trace/events/power.h>

struct sugov_tunables {
@@ -167,7 +168,7 @@ static unsigned int get_next_freq(struct sugov_policy *sg_policy,
unsigned int freq = arch_scale_freq_invariant() ?
policy->cpuinfo.max_freq : policy->cur;

- freq = (freq + (freq >> 2)) * util / max;
+ freq = map_util_freq(util, freq, max);

if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)
return sg_policy->next_freq;
--
2.18.0
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