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Message-ID: <416196db-ad73-42d3-8e52-bc120a822f31@huawei.com>
Date: Wed, 10 Dec 2025 11:01:37 +0800
From: "zhenglifeng (A)" <zhenglifeng1@...wei.com>
To: Pierre Gondois <pierre.gondois@....com>
CC: <linux-kernel@...r.kernel.org>, Christian Loehle
<christian.loehle@....com>, Ionela Voinescu <ionela.voinescu@....com>, Jie
Zhan <zhanjie9@...ilicon.com>, Huang Rui <ray.huang@....com>, "Gautham R.
Shenoy" <gautham.shenoy@....com>, Mario Limonciello
<mario.limonciello@....com>, Perry Yuan <perry.yuan@....com>, "Rafael J.
Wysocki" <rafael@...nel.org>, Viresh Kumar <viresh.kumar@...aro.org>,
<linux-pm@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] cpufreq: Add boost_freq_req QoS request
On 2025/12/8 18:59, Pierre Gondois wrote:
> The Power Management Quality of Service (PM QoS) allows to
> aggregate constraints from multiple entities. It is currently
> used to manage the min/max frequency of a given policy.
>
> Frequency constraints can come for instance from:
> - Thermal framework: acpi_thermal_cpufreq_init()
> - Firmware: _PPC objects: acpi_processor_ppc_init()
> - User: by setting policyX/scaling_[min|max]_freq
> The minimum of the max frequency constraints is used to compute
> the resulting maximum allowed frequency.
>
> When enabling boost frequencies, the same frequency request object
> (policy->max_freq_req) as to handle requests from users is used.
> As a result, when setting:
> - scaling_max_freq
> - boost
> The last sysfs file used overwrites the request from the other
> sysfs file.
>
> To avoid this, create a per-policy boost_freq_req to save the boost
> constraints instead of overwriting the last scaling_max_freq
> constraint.
>
> Signed-off-by: Pierre Gondois <pierre.gondois@....com>
> ---
> drivers/cpufreq/cpufreq.c | 28 ++++++++++++++++++++++++++++
> include/linux/cpufreq.h | 1 +
> 2 files changed, 29 insertions(+)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 852e024facc3c..942416f2741b0 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1359,6 +1359,11 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy)
> /* Cancel any pending policy->update work before freeing the policy. */
> cancel_work_sync(&policy->update);
>
> + if (policy->boost_freq_req) {
> + freq_qos_remove_request(policy->boost_freq_req);
> + kfree(policy->boost_freq_req);
> + }
> +
> if (policy->max_freq_req) {
> /*
> * Remove max_freq_req after sending CPUFREQ_REMOVE_POLICY
If adding boost_freq_req fails, CPUFREQ_CREATE_POLICY notification will
never be sent but CPUFREQ_REMOVE_POLICY notification will be sent here. So
maybe something like this is better:
@@ -1365,17 +1365,28 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy)
/* Cancel any pending policy->update work before freeing the policy. */
cancel_work_sync(&policy->update);
- if (policy->max_freq_req) {
+ if (policy->boost_freq_req) {
/*
- * Remove max_freq_req after sending CPUFREQ_REMOVE_POLICY
+ * Remove boost_freq_req after sending CPUFREQ_REMOVE_POLICY
* notification, since CPUFREQ_CREATE_POLICY notification was
- * sent after adding max_freq_req earlier.
+ * sent after adding boost_freq_req earlier.
*/
blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
CPUFREQ_REMOVE_POLICY, policy);
- freq_qos_remove_request(policy->max_freq_req);
+ freq_qos_remove_request(policy->boost_freq_req);
+ kfree(policy->boost_freq_req);
}
+ if (policy->max_freq_req && !policy->boost_supported) {
+ /*
+ * Send CPUFREQ_REMOVE_POLICY notification here if
+ * boost_freq_req is not present.
+ */
+ blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+ CPUFREQ_REMOVE_POLICY, policy);
+ }
+
+ freq_qos_remove_request(policy->max_freq_req);
freq_qos_remove_request(policy->min_freq_req);
kfree(policy->min_freq_req);
---
It's a bit verbose, but I can't think of a better way.
> @@ -1476,6 +1481,29 @@ static int cpufreq_policy_online(struct cpufreq_policy *policy,
> goto out_destroy_policy;
> }
>
> + if (policy->boost_supported) {
> + policy->boost_freq_req = kzalloc(sizeof(*policy->boost_freq_req),
> + GFP_KERNEL);
> + if (!policy->boost_freq_req) {
> + ret = -ENOMEM;
> + goto out_destroy_policy;
> + }
> +
> + ret = freq_qos_add_request(&policy->constraints,
> + policy->boost_freq_req,
> + FREQ_QOS_MAX,
> + FREQ_QOS_MAX_DEFAULT_VALUE);
> + if (ret < 0) {
> + /*
> + * So we don't call freq_qos_remove_request() for an
> + * uninitialized request.
> + */
> + kfree(policy->boost_freq_req);
> + policy->boost_freq_req = NULL;
> + goto out_destroy_policy;
> + }
> + }
> +
> blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
> CPUFREQ_CREATE_POLICY, policy);
> } else {
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index 0465d1e6f72ac..c292a6a19e4f5 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -81,6 +81,7 @@ struct cpufreq_policy {
> struct freq_constraints constraints;
> struct freq_qos_request *min_freq_req;
> struct freq_qos_request *max_freq_req;
> + struct freq_qos_request *boost_freq_req;
>
> struct cpufreq_frequency_table *freq_table;
> enum cpufreq_table_sorting freq_table_sorted;
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