* [PATCH v2] cpufreq/amd-pstate: Cache the max frequency in cpudata
@ 2026-03-23 4:32 Mario Limonciello (AMD)
2026-03-24 3:54 ` Zhongqiu Han
0 siblings, 1 reply; 2+ messages in thread
From: Mario Limonciello (AMD) @ 2026-03-23 4:32 UTC (permalink / raw)
To: Gautham R . Shenoy
Cc: Perry Yuan, open list:X86 ARCHITECTURE (32-BIT AND 64-BIT),
open list:CPU FREQUENCY SCALING FRAMEWORK,
Mario Limonciello (AMD)
The value of maximum frequency is fixed and never changes. Doing
calculations every time based off of perf is unnecessary.
Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
---
v2:
* Remove unused variable
---
drivers/cpufreq/amd-pstate.c | 27 +++++++++------------------
drivers/cpufreq/amd-pstate.h | 1 +
2 files changed, 10 insertions(+), 18 deletions(-)
diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
index 5aa9fcd80cf51..9f80f8b23a43f 100644
--- a/drivers/cpufreq/amd-pstate.c
+++ b/drivers/cpufreq/amd-pstate.c
@@ -757,15 +757,13 @@ static void amd_pstate_adjust_perf(unsigned int cpu,
static int amd_pstate_cpu_boost_update(struct cpufreq_policy *policy, bool on)
{
struct amd_cpudata *cpudata = policy->driver_data;
- union perf_cached perf = READ_ONCE(cpudata->perf);
- u32 nominal_freq, max_freq;
+ u32 nominal_freq;
int ret = 0;
nominal_freq = READ_ONCE(cpudata->nominal_freq);
- max_freq = perf_to_freq(perf, cpudata->nominal_freq, perf.highest_perf);
if (on)
- policy->cpuinfo.max_freq = max_freq;
+ policy->cpuinfo.max_freq = cpudata->max_freq;
else if (policy->cpuinfo.max_freq > nominal_freq)
policy->cpuinfo.max_freq = nominal_freq;
@@ -952,13 +950,15 @@ static int amd_pstate_init_freq(struct amd_cpudata *cpudata)
WRITE_ONCE(cpudata->nominal_freq, nominal_freq);
+ /* max_freq is calculated according to (nominal_freq * highest_perf)/nominal_perf */
max_freq = perf_to_freq(perf, nominal_freq, perf.highest_perf);
+ WRITE_ONCE(cpudata->max_freq, max_freq);
+
lowest_nonlinear_freq = perf_to_freq(perf, nominal_freq, perf.lowest_nonlinear_perf);
WRITE_ONCE(cpudata->lowest_nonlinear_freq, lowest_nonlinear_freq);
/**
* Below values need to be initialized correctly, otherwise driver will fail to load
- * max_freq is calculated according to (nominal_freq * highest_perf)/nominal_perf
* lowest_nonlinear_freq is a value between [min_freq, nominal_freq]
* Check _CPC in ACPI table objects if any values are incorrect
*/
@@ -1021,9 +1021,7 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
policy->cpuinfo.min_freq = policy->min = perf_to_freq(perf,
cpudata->nominal_freq,
perf.lowest_perf);
- policy->cpuinfo.max_freq = policy->max = perf_to_freq(perf,
- cpudata->nominal_freq,
- perf.highest_perf);
+ policy->cpuinfo.max_freq = policy->max = cpudata->max_freq;
ret = amd_pstate_cppc_enable(policy);
if (ret)
@@ -1090,14 +1088,9 @@ static void amd_pstate_cpu_exit(struct cpufreq_policy *policy)
static ssize_t show_amd_pstate_max_freq(struct cpufreq_policy *policy,
char *buf)
{
- struct amd_cpudata *cpudata;
- union perf_cached perf;
-
- cpudata = policy->driver_data;
- perf = READ_ONCE(cpudata->perf);
+ struct amd_cpudata *cpudata = policy->driver_data;
- return sysfs_emit(buf, "%u\n",
- perf_to_freq(perf, cpudata->nominal_freq, perf.highest_perf));
+ return sysfs_emit(buf, "%u\n", cpudata->max_freq);
}
static ssize_t show_amd_pstate_lowest_nonlinear_freq(struct cpufreq_policy *policy,
@@ -1503,9 +1496,7 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
policy->cpuinfo.min_freq = policy->min = perf_to_freq(perf,
cpudata->nominal_freq,
perf.lowest_perf);
- policy->cpuinfo.max_freq = policy->max = perf_to_freq(perf,
- cpudata->nominal_freq,
- perf.highest_perf);
+ policy->cpuinfo.max_freq = policy->max = cpudata->max_freq;
policy->driver_data = cpudata;
ret = amd_pstate_cppc_enable(policy);
diff --git a/drivers/cpufreq/amd-pstate.h b/drivers/cpufreq/amd-pstate.h
index cb45fdca27a6c..485ee023d79c5 100644
--- a/drivers/cpufreq/amd-pstate.h
+++ b/drivers/cpufreq/amd-pstate.h
@@ -94,6 +94,7 @@ struct amd_cpudata {
u32 min_limit_freq;
u32 max_limit_freq;
u32 nominal_freq;
+ u32 max_freq;
u32 lowest_nonlinear_freq;
struct amd_aperf_mperf cur;
--
2.43.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH v2] cpufreq/amd-pstate: Cache the max frequency in cpudata
2026-03-23 4:32 [PATCH v2] cpufreq/amd-pstate: Cache the max frequency in cpudata Mario Limonciello (AMD)
@ 2026-03-24 3:54 ` Zhongqiu Han
0 siblings, 0 replies; 2+ messages in thread
From: Zhongqiu Han @ 2026-03-24 3:54 UTC (permalink / raw)
To: Mario Limonciello (AMD), Gautham R . Shenoy
Cc: Perry Yuan, open list:X86 ARCHITECTURE (32-BIT AND 64-BIT),
open list:CPU FREQUENCY SCALING FRAMEWORK, zhongqiu.han
On 3/23/2026 12:32 PM, Mario Limonciello (AMD) wrote:
> The value of maximum frequency is fixed and never changes. Doing
> calculations every time based off of perf is unnecessary.
>
> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
> ---
> v2:
> * Remove unused variable
> ---
> drivers/cpufreq/amd-pstate.c | 27 +++++++++------------------
> drivers/cpufreq/amd-pstate.h | 1 +
> 2 files changed, 10 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 5aa9fcd80cf51..9f80f8b23a43f 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -757,15 +757,13 @@ static void amd_pstate_adjust_perf(unsigned int cpu,
> static int amd_pstate_cpu_boost_update(struct cpufreq_policy *policy, bool on)
> {
> struct amd_cpudata *cpudata = policy->driver_data;
> - union perf_cached perf = READ_ONCE(cpudata->perf);
> - u32 nominal_freq, max_freq;
> + u32 nominal_freq;
> int ret = 0;
>
> nominal_freq = READ_ONCE(cpudata->nominal_freq);
> - max_freq = perf_to_freq(perf, cpudata->nominal_freq, perf.highest_perf);
>
> if (on)
> - policy->cpuinfo.max_freq = max_freq;
> + policy->cpuinfo.max_freq = cpudata->max_freq;
> else if (policy->cpuinfo.max_freq > nominal_freq)
> policy->cpuinfo.max_freq = nominal_freq;
>
> @@ -952,13 +950,15 @@ static int amd_pstate_init_freq(struct amd_cpudata *cpudata)
>
> WRITE_ONCE(cpudata->nominal_freq, nominal_freq);
>
> + /* max_freq is calculated according to (nominal_freq * highest_perf)/nominal_perf */
> max_freq = perf_to_freq(perf, nominal_freq, perf.highest_perf);
> + WRITE_ONCE(cpudata->max_freq, max_freq);
> +
> lowest_nonlinear_freq = perf_to_freq(perf, nominal_freq, perf.lowest_nonlinear_perf);
> WRITE_ONCE(cpudata->lowest_nonlinear_freq, lowest_nonlinear_freq);
>
> /**
> * Below values need to be initialized correctly, otherwise driver will fail to load
> - * max_freq is calculated according to (nominal_freq * highest_perf)/nominal_perf
> * lowest_nonlinear_freq is a value between [min_freq, nominal_freq]
> * Check _CPC in ACPI table objects if any values are incorrect
> */
> @@ -1021,9 +1021,7 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
> policy->cpuinfo.min_freq = policy->min = perf_to_freq(perf,
> cpudata->nominal_freq,
> perf.lowest_perf);
> - policy->cpuinfo.max_freq = policy->max = perf_to_freq(perf,
> - cpudata->nominal_freq,
> - perf.highest_perf);
> + policy->cpuinfo.max_freq = policy->max = cpudata->max_freq;
>
> ret = amd_pstate_cppc_enable(policy);
> if (ret)
> @@ -1090,14 +1088,9 @@ static void amd_pstate_cpu_exit(struct cpufreq_policy *policy)
> static ssize_t show_amd_pstate_max_freq(struct cpufreq_policy *policy,
> char *buf)
> {
> - struct amd_cpudata *cpudata;
> - union perf_cached perf;
> -
> - cpudata = policy->driver_data;
> - perf = READ_ONCE(cpudata->perf);
> + struct amd_cpudata *cpudata = policy->driver_data;
>
> - return sysfs_emit(buf, "%u\n",
> - perf_to_freq(perf, cpudata->nominal_freq, perf.highest_perf));
> + return sysfs_emit(buf, "%u\n", cpudata->max_freq);
> }
>
> static ssize_t show_amd_pstate_lowest_nonlinear_freq(struct cpufreq_policy *policy,
> @@ -1503,9 +1496,7 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> policy->cpuinfo.min_freq = policy->min = perf_to_freq(perf,
> cpudata->nominal_freq,
> perf.lowest_perf);
> - policy->cpuinfo.max_freq = policy->max = perf_to_freq(perf,
> - cpudata->nominal_freq,
> - perf.highest_perf);
> + policy->cpuinfo.max_freq = policy->max = cpudata->max_freq;
> policy->driver_data = cpudata;
>
> ret = amd_pstate_cppc_enable(policy);
> diff --git a/drivers/cpufreq/amd-pstate.h b/drivers/cpufreq/amd-pstate.h
> index cb45fdca27a6c..485ee023d79c5 100644
> --- a/drivers/cpufreq/amd-pstate.h
> +++ b/drivers/cpufreq/amd-pstate.h
> @@ -94,6 +94,7 @@ struct amd_cpudata {
> u32 min_limit_freq;
> u32 max_limit_freq;
> u32 nominal_freq;
> + u32 max_freq;
Hi Mario,
A minor finding: the new u32 max_freq field is missing a kdoc entry in
struct amd_cpudata.
> u32 lowest_nonlinear_freq;
>
> struct amd_aperf_mperf cur;
--
Thx and BRs,
Zhongqiu Han
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