[PATCH v1 09/10] cpufreq: Introduce cpufreq_policy_refresh()

Rafael J. Wysocki
2025-03-28T20:51:42Z

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Since cpufreq_update_limits() obtains a cpufreq policy pointer for the
given CPU and reference counts the object pointed to by it, calling
cpufreq_update_policy() from cpufreq_update_limits() is somewhat
wasteful because that function calls cpufreq_cpu_get() on the same
CPU again.

To avoid that unnecessary overhead, move the part of the code running
under the policy rwsem from cpufreq_update_policy() to a new function
called cpufreq_policy_refresh() and invoke that new function from
both cpufreq_update_policy() and cpufreq_update_limits().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/cpufreq/cpufreq.c | 31 ++++++++++++++++++-------------
1 file changed, 18 insertions(+), 13 deletions(-)

--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2689,6 +2689,21 @@
return ret;
}

+static void cpufreq_policy_refresh(struct cpufreq_policy *policy)
+{
+ guard(cpufreq_policy_write)(policy);
+
+ /*
+ * BIOS might change freq behind our back
+ * -> ask driver for current freq and notify governors about a change
+ */
+ if (cpufreq_driver->get && has_target() &&
+ (cpufreq_suspended || WARN_ON(!cpufreq_verify_current_freq(policy, false))))
+ return;
+
+ refresh_frequency_limits(policy);
+}
+
/**
* cpufreq_update_policy - Re-evaluate an existing cpufreq policy.
* @cpu: CPU to re-evaluate the policy for.
@@ -2706,17 +2721,7 @@
if (!policy)
return;

- guard(cpufreq_policy_write)(policy);
-
- /*
- * BIOS might change freq behind our back
- * -> ask driver for current freq and notify governors about a change
- */
- if (cpufreq_driver->get && has_target() &&
- (cpufreq_suspended || WARN_ON(!cpufreq_verify_current_freq(policy, false))))
- return;
-
- refresh_frequency_limits(policy);
+ cpufreq_policy_refresh(policy);
}
EXPORT_SYMBOL(cpufreq_update_policy);

@@ -2725,7 +2730,7 @@
* @cpu: CPU to update the policy limits for.
*
* Invoke the driver's ->update_limits callback if present or call
- * cpufreq_update_policy() for @cpu.
+ * cpufreq_policy_refresh() for @cpu.
*/
void cpufreq_update_limits(unsigned int cpu)
{
@@ -2738,7 +2743,7 @@
if (cpufreq_driver->update_limits)
cpufreq_driver->update_limits(cpu);
else
- cpufreq_update_policy(cpu);
+ cpufreq_policy_refresh(policy);
}
EXPORT_SYMBOL_GPL(cpufreq_update_limits);