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Message-Id: <20240820163512.1096301-4-qyousef@layalina.io>
Date: Tue, 20 Aug 2024 17:34:59 +0100
From: Qais Yousef <qyousef@...alina.io>
To: Ingo Molnar <mingo@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Vincent Guittot <vincent.guittot@...aro.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Viresh Kumar <viresh.kumar@...aro.org>
Cc: Juri Lelli <juri.lelli@...hat.com>,
Steven Rostedt <rostedt@...dmis.org>,
Dietmar Eggemann <dietmar.eggemann@....com>,
John Stultz <jstultz@...gle.com>,
linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org,
Qais Yousef <qyousef@...alina.io>
Subject: [RFC PATCH 03/16] sched/pelt: Add a new function to approximate runtime to reach given util
It is basically the ramp-up time from 0 to a given value. Will be used
later to implement new tunable to control response time for schedutil.
Signed-off-by: Qais Yousef <qyousef@...alina.io>
---
kernel/sched/pelt.c | 21 +++++++++++++++++++++
kernel/sched/sched.h | 1 +
2 files changed, 22 insertions(+)
diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c
index 2ce83e880bd5..06cb881ba582 100644
--- a/kernel/sched/pelt.c
+++ b/kernel/sched/pelt.c
@@ -487,3 +487,24 @@ unsigned long approximate_util_avg(unsigned long util, u64 delta)
return sa.util_avg;
}
+
+/*
+ * Approximate the required amount of runtime in ms required to reach @util.
+ */
+u64 approximate_runtime(unsigned long util)
+{
+ struct sched_avg sa = {};
+ u64 delta = 1024; // period = 1024 = ~1ms
+ u64 runtime = 0;
+
+ if (unlikely(!util))
+ return runtime;
+
+ while (sa.util_avg < util) {
+ accumulate_sum(delta, &sa, 1, 0, 1);
+ ___update_load_avg(&sa, 0);
+ runtime++;
+ }
+
+ return runtime;
+}
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 294c6769e330..47f158b2cdc2 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -3065,6 +3065,7 @@ unsigned long sugov_effective_cpu_perf(int cpu, unsigned long actual,
unsigned long max);
unsigned long approximate_util_avg(unsigned long util, u64 delta);
+u64 approximate_runtime(unsigned long util);
/*
* Verify the fitness of task @p to run on @cpu taking into account the
--
2.34.1
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