[PATCH v6 2/4] cpufreq: Add boost_freq_req QoS request
From: Pierre Gondois
Date: Tue Mar 17 2026 - 06:21:35 EST
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.
policy_set_boost() calls the cpufreq set_boost callback.
Update the newly added boost_freq_req request from there:
- whenever boost is toggled
- to cover all possible paths
In the existing .set_boost() callbacks:
- Don't update policy->max as this is done through the qos notifier
cpufreq_notifier_max() which calls cpufreq_set_policy().
- Remove freq_qos_update_request() calls as the qos request is now
done in policy_set_boost() and updates the new boost_freq_req
$ ## Init state
scaling_max_freq:1000000
cpuinfo_max_freq:1000000
$ echo 700000 > scaling_max_freq
scaling_max_freq:700000
cpuinfo_max_freq:1000000
$ echo 1 > ../boost
scaling_max_freq:1200000
cpuinfo_max_freq:1200000
$ echo 800000 > scaling_max_freq
scaling_max_freq:800000
cpuinfo_max_freq:1200000
$ ## Final step:
$ ## Without the patches:
$ echo 0 > ../boost
scaling_max_freq:1000000
cpuinfo_max_freq:1000000
$ ## With the patches:
$ echo 0 > ../boost
scaling_max_freq:800000
cpuinfo_max_freq:1000000
Note:
cpufreq_frequency_table_cpuinfo() updates policy->min
and max from:
A.
cpufreq_boost_set_sw()
\-cpufreq_frequency_table_cpuinfo()
B.
cpufreq_policy_online()
\-cpufreq_table_validate_and_sort()
\-cpufreq_frequency_table_cpuinfo()
Keep these updates as some drivers expect policy->min and
max to be set through B.
Signed-off-by: Pierre Gondois <pierre.gondois@xxxxxxx>
---
drivers/cpufreq/amd-pstate.c | 2 --
drivers/cpufreq/cppc_cpufreq.c | 10 ++-----
drivers/cpufreq/cpufreq.c | 52 +++++++++++++++++++++++++++-------
include/linux/cpufreq.h | 1 +
4 files changed, 44 insertions(+), 21 deletions(-)
diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index c45bc98721d24..310d5938cbdf6 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -756,8 +756,6 @@ static int amd_pstate_cpu_boost_update(struct cpufreq_policy *policy, bool on)
else if (policy->cpuinfo.max_freq > nominal_freq)
policy->cpuinfo.max_freq = nominal_freq;
- policy->max = policy->cpuinfo.max_freq;
-
if (cppc_state == AMD_PSTATE_PASSIVE) {
ret = freq_qos_update_request(&cpudata->req[1], policy->cpuinfo.max_freq);
if (ret < 0)
diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index 9eac77c4f2944..4c46c7ea318eb 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -775,17 +775,11 @@ static int cppc_cpufreq_set_boost(struct cpufreq_policy *policy, int state)
{
struct cppc_cpudata *cpu_data = policy->driver_data;
struct cppc_perf_caps *caps = &cpu_data->perf_caps;
- int ret;
if (state)
- policy->max = cppc_perf_to_khz(caps, caps->highest_perf);
+ policy->cpuinfo.max_freq = cppc_perf_to_khz(caps, caps->highest_perf);
else
- policy->max = cppc_perf_to_khz(caps, caps->nominal_perf);
- policy->cpuinfo.max_freq = policy->max;
-
- ret = freq_qos_update_request(policy->max_freq_req, policy->max);
- if (ret < 0)
- return ret;
+ policy->cpuinfo.max_freq = cppc_perf_to_khz(caps, caps->nominal_perf);
return 0;
}
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index db414c052658b..e4f24754df164 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -603,10 +603,19 @@ static int policy_set_boost(struct cpufreq_policy *policy, bool enable)
policy->boost_enabled = enable;
ret = cpufreq_driver->set_boost(policy, enable);
- if (ret)
+ if (ret) {
policy->boost_enabled = !policy->boost_enabled;
+ return ret;
+ }
- return ret;
+ ret = freq_qos_update_request(policy->boost_freq_req, policy->cpuinfo.max_freq);
+ if (ret < 0) {
+ policy->boost_enabled = !policy->boost_enabled;
+ cpufreq_driver->set_boost(policy, policy->boost_enabled);
+ return ret;
+ }
+
+ return 0;
}
static ssize_t store_local_boost(struct cpufreq_policy *policy,
@@ -1370,6 +1379,9 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy)
freq_qos_remove_request(policy->max_freq_req);
}
+ if (policy->boost_freq_req)
+ freq_qos_remove_request(policy->boost_freq_req);
+
freq_qos_remove_request(policy->min_freq_req);
kfree(policy->min_freq_req);
@@ -1439,12 +1451,15 @@ static int cpufreq_policy_online(struct cpufreq_policy *policy,
cpumask_and(policy->cpus, policy->cpus, cpu_online_mask);
if (new_policy) {
+ unsigned int req_nr;
+
for_each_cpu(j, policy->related_cpus) {
per_cpu(cpufreq_cpu_data, j) = policy;
add_cpu_dev_symlink(policy, j, get_cpu_device(j));
}
- policy->min_freq_req = kzalloc(2 * sizeof(*policy->min_freq_req),
+ req_nr = policy->boost_supported ? 3 : 2;
+ policy->min_freq_req = kzalloc(req_nr * sizeof(*policy->min_freq_req),
GFP_KERNEL);
if (!policy->min_freq_req) {
ret = -ENOMEM;
@@ -1479,6 +1494,27 @@ static int cpufreq_policy_online(struct cpufreq_policy *policy,
goto out_destroy_policy;
}
+ if (policy->boost_supported) {
+ policy->boost_freq_req = policy->max_freq_req + 1;
+
+ /*
+ * If boost is supported,
+ * init the constraint with cpuinfo.max_freq.
+ */
+ ret = freq_qos_add_request(&policy->constraints,
+ policy->boost_freq_req,
+ FREQ_QOS_MAX,
+ policy->cpuinfo.max_freq);
+ if (ret < 0) {
+ /*
+ * So we don't call freq_qos_remove_request() for an
+ * uninitialized request.
+ */
+ policy->boost_freq_req = NULL;
+ goto out_destroy_policy;
+ }
+ }
+
blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
CPUFREQ_CREATE_POLICY, policy);
}
@@ -2782,16 +2818,10 @@ int cpufreq_boost_set_sw(struct cpufreq_policy *policy, int state)
return -ENXIO;
ret = cpufreq_frequency_table_cpuinfo(policy);
- if (ret) {
+ if (ret)
pr_err("%s: Policy frequency update failed\n", __func__);
- return ret;
- }
-
- ret = freq_qos_update_request(policy->max_freq_req, policy->max);
- if (ret < 0)
- return ret;
- return 0;
+ return ret;
}
EXPORT_SYMBOL_GPL(cpufreq_boost_set_sw);
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;
--
2.43.0