linux-kernel - [PATCH 07/15] cpufreq: ondemand: Simplify idle cputime granularity test

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Message-ID: <20260116145208.87445-8-frederic@kernel.org>
Date: Fri, 16 Jan 2026 15:52:00 +0100
From: Frederic Weisbecker <frederic@...nel.org>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Frederic Weisbecker <frederic@...nel.org>,
	"Christophe Leroy (CS GROUP)" <chleroy@...nel.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Alexander Gordeev <agordeev@...ux.ibm.com>,
	Anna-Maria Behnsen <anna-maria@...utronix.de>,
	Ben Segall <bsegall@...gle.com>,
	Boqun Feng <boqun.feng@...il.com>,
	Christian Borntraeger <borntraeger@...ux.ibm.com>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Heiko Carstens <hca@...ux.ibm.com>,
	Ingo Molnar <mingo@...hat.com>,
	Jan Kiszka <jan.kiszka@...mens.com>,
	Joel Fernandes <joelagnelf@...dia.com>,
	Juri Lelli <juri.lelli@...hat.com>,
	Kieran Bingham <kbingham@...nel.org>,
	Madhavan Srinivasan <maddy@...ux.ibm.com>,
	Mel Gorman <mgorman@...e.de>,
	Michael Ellerman <mpe@...erman.id.au>,
	Neeraj Upadhyay <neeraj.upadhyay@...nel.org>,
	Nicholas Piggin <npiggin@...il.com>,
	"Paul E . McKenney" <paulmck@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Sven Schnelle <svens@...ux.ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Uladzislau Rezki <urezki@...il.com>,
	Valentin Schneider <vschneid@...hat.com>,
	Vasily Gorbik <gor@...ux.ibm.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Xin Zhao <jackzxcui1989@....com>,
	linux-pm@...r.kernel.org,
	linux-s390@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH 07/15] cpufreq: ondemand: Simplify idle cputime granularity test

cpufreq calls get_cpu_idle_time_us() just to know if idle cputime
accounting has a nanoseconds granularity.

Use the appropriate indicator instead to make that deduction.

Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
---
 drivers/cpufreq/cpufreq_ondemand.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/cpufreq/cpufreq_ondemand.c b/drivers/cpufreq/cpufreq_ondemand.c
index a6ecc203f7b7..2d52ee035702 100644
--- a/drivers/cpufreq/cpufreq_ondemand.c
+++ b/drivers/cpufreq/cpufreq_ondemand.c
@@ -334,17 +334,12 @@ static void od_free(struct policy_dbs_info *policy_dbs)
 static int od_init(struct dbs_data *dbs_data)
 {
 	struct od_dbs_tuners *tuners;
-	u64 idle_time;
-	int cpu;
 
 	tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
 	if (!tuners)
 		return -ENOMEM;
 
-	cpu = get_cpu();
-	idle_time = get_cpu_idle_time_us(cpu, NULL);
-	put_cpu();
-	if (idle_time != -1ULL) {
+	if (tick_nohz_enabled) {
 		/* Idle micro accounting is supported. Use finer thresholds */
 		dbs_data->up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
 	} else {
-- 
2.51.1