Messages in this thread Patch in this message | | | From | Qais Yousef <> | Subject | [PATCH] sched: cpufreq: Rename map_util_perf to apply_dvfs_headroom | Date | Mon, 5 Feb 2024 02:20:06 +0000 |
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We are providing headroom for the utilization to grow until the next decision point to pick the next frequency. Give the function a better name and give it some documentation. It is not really mapping anything.
Also move it to sched.h. This function relies on updating util signal appropriately to give a headroom to grow. This is more of a scheduler functionality than cpufreq. Move it to sched.h where all the other util handling code belongs.
Signed-off-by: Qais Yousef <qyousef@layalina.io> --- include/linux/sched/cpufreq.h | 5 ----- kernel/sched/cpufreq_schedutil.c | 2 +- kernel/sched/sched.h | 17 +++++++++++++++++ 3 files changed, 18 insertions(+), 6 deletions(-)
diff --git a/include/linux/sched/cpufreq.h b/include/linux/sched/cpufreq.h index bdd31ab93bc5..d01755d3142f 100644 --- a/include/linux/sched/cpufreq.h +++ b/include/linux/sched/cpufreq.h @@ -28,11 +28,6 @@ static inline unsigned long map_util_freq(unsigned long util, { return freq * util / cap; } - -static inline unsigned long map_util_perf(unsigned long util) -{ - return util + (util >> 2); -} #endif /* CONFIG_CPU_FREQ */ #endif /* _LINUX_SCHED_CPUFREQ_H */ diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index 95c3c097083e..abbd1ddb0359 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -179,7 +179,7 @@ unsigned long sugov_effective_cpu_perf(int cpu, unsigned long actual, unsigned long max) { /* Add dvfs headroom to actual utilization */ - actual = map_util_perf(actual); + actual = apply_dvfs_headroom(actual); /* Actually we don't need to target the max performance */ if (actual < max) max = actual; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index e58a54bda77d..0da3425200b1 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -3002,6 +3002,23 @@ unsigned long sugov_effective_cpu_perf(int cpu, unsigned long actual, unsigned long min, unsigned long max); +/* + * DVFS decision are made at discrete points. If CPU stays busy, the util will + * continue to grow, which means it could need to run at a higher frequency + * before the next decision point was reached. IOW, we can't follow the util as + * it grows immediately, but there's a delay before we issue a request to go to + * higher frequency. The headroom caters for this delay so the system continues + * to run at adequate performance point. + * + * This function provides enough headroom to provide adequate performance + * assuming the CPU continues to be busy. + * + * At the moment it is a constant multiplication with 1.25. + */ +static inline unsigned long apply_dvfs_headroom(unsigned long util) +{ + return util + (util >> 2); +} /* * Verify the fitness of task @p to run on @cpu taking into account the -- 2.34.1
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