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Message-ID: <e297cb9c-0fc9-4cfb-89c8-6bad5ca9c9e9@kernel.org>
Date: Fri, 7 Feb 2025 10:15:46 -0600
From: Mario Limonciello <superm1@...nel.org>
To: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>,
"Gautham R . Shenoy" <gautham.shenoy@....com>,
Perry Yuan <perry.yuan@....com>
Cc: "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<linux-kernel@...r.kernel.org>,
"open list:CPU FREQUENCY SCALING FRAMEWORK" <linux-pm@...r.kernel.org>,
Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCH 02/14] cpufreq/amd-pstate: Drop min and max cached
frequencies
On 2/7/2025 04:44, Dhananjay Ugwekar wrote:
> Hello Mario,
>
> On 2/7/2025 3:26 AM, Mario Limonciello wrote:
>> From: Mario Limonciello <mario.limonciello@....com>
>>
>> Use the perf_to_freq helpers to calculate this on the fly.
>
> I think there is a benefit to having the min/max_limit_freq values cached.
> These values help us avoid unnecessary amd_pstate_update_min_max_limit() calls in
> majority of cases (where the policy->min/max values didnt change).
>
> For the cpudata->min/max_freq values, I think there is little value in caching them,
> i.e. only used in amd_pstate_cpu_boost_update() and show_amd_pstate_max_freq(), which
> are not supposed to be called very frequently.
>
> So, I propose we keep the cpudata->min/max_limit_freq variables and remove the
> cpudata->min/max_freq ones. Thoughts?
Yeah I can see this argument making sense and worthwhile keeping the
caching. I'll modify it for the next version.
>
> Thanks,
> Dhananjay
>
>>
>> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
>> ---
>> drivers/cpufreq/amd-pstate-ut.c | 14 +++----
>> drivers/cpufreq/amd-pstate.c | 74 ++++++++++-----------------------
>> drivers/cpufreq/amd-pstate.h | 8 ----
>> 3 files changed, 29 insertions(+), 67 deletions(-)
>>
>> diff --git a/drivers/cpufreq/amd-pstate-ut.c b/drivers/cpufreq/amd-pstate-ut.c
>> index 3a0a380c3590c..445278cf40b61 100644
>> --- a/drivers/cpufreq/amd-pstate-ut.c
>> +++ b/drivers/cpufreq/amd-pstate-ut.c
>> @@ -214,14 +214,14 @@ static void amd_pstate_ut_check_freq(u32 index)
>> break;
>> cpudata = policy->driver_data;
>>
>> - if (!((cpudata->max_freq >= cpudata->nominal_freq) &&
>> + if (!((policy->cpuinfo.max_freq >= cpudata->nominal_freq) &&
>> (cpudata->nominal_freq > cpudata->lowest_nonlinear_freq) &&
>> - (cpudata->lowest_nonlinear_freq > cpudata->min_freq) &&
>> - (cpudata->min_freq > 0))) {
>> + (cpudata->lowest_nonlinear_freq > policy->cpuinfo.min_freq) &&
>> + (policy->cpuinfo.min_freq > 0))) {
>> amd_pstate_ut_cases[index].result = AMD_PSTATE_UT_RESULT_FAIL;
>> pr_err("%s cpu%d max=%d >= nominal=%d > lowest_nonlinear=%d > min=%d > 0, the formula is incorrect!\n",
>> - __func__, cpu, cpudata->max_freq, cpudata->nominal_freq,
>> - cpudata->lowest_nonlinear_freq, cpudata->min_freq);
>> + __func__, cpu, policy->cpuinfo.max_freq, cpudata->nominal_freq,
>> + cpudata->lowest_nonlinear_freq, policy->cpuinfo.min_freq);
>> goto skip_test;
>> }
>>
>> @@ -233,13 +233,13 @@ static void amd_pstate_ut_check_freq(u32 index)
>> }
>>
>> if (cpudata->boost_supported) {
>> - if ((policy->max == cpudata->max_freq) ||
>> + if ((policy->max == policy->cpuinfo.max_freq) ||
>> (policy->max == cpudata->nominal_freq))
>> amd_pstate_ut_cases[index].result = AMD_PSTATE_UT_RESULT_PASS;
>> else {
>> amd_pstate_ut_cases[index].result = AMD_PSTATE_UT_RESULT_FAIL;
>> pr_err("%s cpu%d policy_max=%d should be equal cpu_max=%d or cpu_nominal=%d !\n",
>> - __func__, cpu, policy->max, cpudata->max_freq,
>> + __func__, cpu, policy->max, policy->cpuinfo.max_freq,
>> cpudata->nominal_freq);
>> goto skip_test;
>> }
>> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
>> index 573643654e8d6..668377f55b630 100644
>> --- a/drivers/cpufreq/amd-pstate.c
>> +++ b/drivers/cpufreq/amd-pstate.c
>> @@ -615,8 +615,6 @@ static int amd_pstate_update_min_max_limit(struct cpufreq_policy *policy)
>>
>> WRITE_ONCE(cpudata->max_limit_perf, max_limit_perf);
>> WRITE_ONCE(cpudata->min_limit_perf, min_limit_perf);
>> - WRITE_ONCE(cpudata->max_limit_freq, policy->max);
>> - WRITE_ONCE(cpudata->min_limit_freq, policy->min);
>>
>> return 0;
>> }
>> @@ -628,8 +626,7 @@ static int amd_pstate_update_freq(struct cpufreq_policy *policy,
>> struct amd_cpudata *cpudata = policy->driver_data;
>> u8 des_perf;
>>
>> - if (policy->min != cpudata->min_limit_freq || policy->max != cpudata->max_limit_freq)
>> - amd_pstate_update_min_max_limit(policy);
>> + amd_pstate_update_min_max_limit(policy);
>>
>> freqs.old = policy->cur;
>> freqs.new = target_freq;
>> @@ -684,8 +681,7 @@ static void amd_pstate_adjust_perf(unsigned int cpu,
>>
>> cpudata = policy->driver_data;
>>
>> - if (policy->min != cpudata->min_limit_freq || policy->max != cpudata->max_limit_freq)
>> - amd_pstate_update_min_max_limit(policy);
>> + amd_pstate_update_min_max_limit(policy);
>>
>> cap_perf = READ_ONCE(cpudata->highest_perf);
>> min_limit_perf = READ_ONCE(cpudata->min_limit_perf);
>> @@ -717,7 +713,7 @@ static int amd_pstate_cpu_boost_update(struct cpufreq_policy *policy, bool on)
>> int ret = 0;
>>
>> nominal_freq = READ_ONCE(cpudata->nominal_freq);
>> - max_freq = READ_ONCE(cpudata->max_freq);
>> + max_freq = perf_to_freq(cpudata, READ_ONCE(cpudata->highest_perf));
>>
>> if (on)
>> policy->cpuinfo.max_freq = max_freq;
>> @@ -901,35 +897,25 @@ static u32 amd_pstate_get_transition_latency(unsigned int cpu)
>> static int amd_pstate_init_freq(struct amd_cpudata *cpudata)
>> {
>> int ret;
>> - u32 min_freq, max_freq;
>> - u32 nominal_freq, lowest_nonlinear_freq;
>> + u32 min_freq, nominal_freq, lowest_nonlinear_freq;
>> struct cppc_perf_caps cppc_perf;
>>
>> ret = cppc_get_perf_caps(cpudata->cpu, &cppc_perf);
>> if (ret)
>> return ret;
>>
>> - if (quirks && quirks->lowest_freq)
>> - min_freq = quirks->lowest_freq;
>> - else
>> - min_freq = cppc_perf.lowest_freq;
>> -
>> if (quirks && quirks->nominal_freq)
>> nominal_freq = quirks->nominal_freq;
>> else
>> nominal_freq = cppc_perf.nominal_freq;
>>
>> - min_freq *= 1000;
>> nominal_freq *= 1000;
>> -
>> WRITE_ONCE(cpudata->nominal_freq, nominal_freq);
>> - WRITE_ONCE(cpudata->min_freq, min_freq);
>>
>> - max_freq = perf_to_freq(cpudata, cpudata->highest_perf);
>> - lowest_nonlinear_freq = perf_to_freq(cpudata, cpudata->lowest_nonlinear_perf);
>> -
>> - WRITE_ONCE(cpudata->lowest_nonlinear_freq, lowest_nonlinear_freq);
>> - WRITE_ONCE(cpudata->max_freq, max_freq);
>> + if (quirks && quirks->lowest_freq) {
>> + min_freq = quirks->lowest_freq;
>> + } else
>> + min_freq = cppc_perf.lowest_freq;
>>
>> /**
>> * Below values need to be initialized correctly, otherwise driver will fail to load
>> @@ -937,12 +923,15 @@ static int amd_pstate_init_freq(struct amd_cpudata *cpudata)
>> * lowest_nonlinear_freq is a value between [min_freq, nominal_freq]
>> * Check _CPC in ACPI table objects if any values are incorrect
>> */
>> - if (min_freq <= 0 || max_freq <= 0 || nominal_freq <= 0 || min_freq > max_freq) {
>> - pr_err("min_freq(%d) or max_freq(%d) or nominal_freq(%d) value is incorrect\n",
>> - min_freq, max_freq, nominal_freq);
>> + if (nominal_freq <= 0) {
>> + pr_err("nominal_freq(%d) value is incorrect\n",
>> + nominal_freq);
>> return -EINVAL;
>> }
>>
>> + lowest_nonlinear_freq = perf_to_freq(cpudata, cpudata->lowest_nonlinear_perf);
>> + WRITE_ONCE(cpudata->lowest_nonlinear_freq, lowest_nonlinear_freq);
>> +
>> if (lowest_nonlinear_freq <= min_freq || lowest_nonlinear_freq > nominal_freq) {
>> pr_err("lowest_nonlinear_freq(%d) value is out of range [min_freq(%d), nominal_freq(%d)]\n",
>> lowest_nonlinear_freq, min_freq, nominal_freq);
>> @@ -954,9 +943,9 @@ static int amd_pstate_init_freq(struct amd_cpudata *cpudata)
>>
>> static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
>> {
>> - int min_freq, max_freq, ret;
>> - struct device *dev;
>> struct amd_cpudata *cpudata;
>> + struct device *dev;
>> + int ret;
>>
>> /*
>> * Resetting PERF_CTL_MSR will put the CPU in P0 frequency,
>> @@ -987,17 +976,11 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
>> if (ret)
>> goto free_cpudata1;
>>
>> - min_freq = READ_ONCE(cpudata->min_freq);
>> - max_freq = READ_ONCE(cpudata->max_freq);
>> -
>> policy->cpuinfo.transition_latency = amd_pstate_get_transition_latency(policy->cpu);
>> policy->transition_delay_us = amd_pstate_get_transition_delay_us(policy->cpu);
>>
>> - policy->min = min_freq;
>> - policy->max = max_freq;
>> -
>> - policy->cpuinfo.min_freq = min_freq;
>> - policy->cpuinfo.max_freq = max_freq;
>> + policy->cpuinfo.min_freq = policy->min = perf_to_freq(cpudata, cpudata->lowest_perf);
>> + policy->cpuinfo.max_freq = policy->max = perf_to_freq(cpudata, cpudata->highest_perf);
>>
>> policy->boost_enabled = READ_ONCE(cpudata->boost_supported);
>>
>> @@ -1021,9 +1004,6 @@ static int amd_pstate_cpu_init(struct cpufreq_policy *policy)
>> goto free_cpudata2;
>> }
>>
>> - cpudata->max_limit_freq = max_freq;
>> - cpudata->min_limit_freq = min_freq;
>> -
>> policy->driver_data = cpudata;
>>
>> if (!current_pstate_driver->adjust_perf)
>> @@ -1081,14 +1061,10 @@ static int amd_pstate_cpu_suspend(struct cpufreq_policy *policy)
>> static ssize_t show_amd_pstate_max_freq(struct cpufreq_policy *policy,
>> char *buf)
>> {
>> - int max_freq;
>> struct amd_cpudata *cpudata = policy->driver_data;
>>
>> - max_freq = READ_ONCE(cpudata->max_freq);
>> - if (max_freq < 0)
>> - return max_freq;
>>
>> - return sysfs_emit(buf, "%u\n", max_freq);
>> + return sysfs_emit(buf, "%u\n", perf_to_freq(cpudata, READ_ONCE(cpudata->highest_perf)));
>> }
>>
>> static ssize_t show_amd_pstate_lowest_nonlinear_freq(struct cpufreq_policy *policy,
>> @@ -1446,10 +1422,10 @@ static bool amd_pstate_acpi_pm_profile_undefined(void)
>>
>> static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
>> {
>> - int min_freq, max_freq, ret;
>> struct amd_cpudata *cpudata;
>> struct device *dev;
>> u64 value;
>> + int ret;
>>
>> /*
>> * Resetting PERF_CTL_MSR will put the CPU in P0 frequency,
>> @@ -1480,19 +1456,13 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
>> if (ret)
>> goto free_cpudata1;
>>
>> - min_freq = READ_ONCE(cpudata->min_freq);
>> - max_freq = READ_ONCE(cpudata->max_freq);
>> -
>> - policy->cpuinfo.min_freq = min_freq;
>> - policy->cpuinfo.max_freq = max_freq;
>> + policy->cpuinfo.min_freq = policy->min = perf_to_freq(cpudata, cpudata->lowest_perf);
>> + policy->cpuinfo.max_freq = policy->max = perf_to_freq(cpudata, cpudata->highest_perf);
>> /* It will be updated by governor */
>> policy->cur = policy->cpuinfo.min_freq;
>>
>> policy->driver_data = cpudata;
>>
>> - policy->min = policy->cpuinfo.min_freq;
>> - policy->max = policy->cpuinfo.max_freq;
>> -
>> policy->boost_enabled = READ_ONCE(cpudata->boost_supported);
>>
>> /*
>> diff --git a/drivers/cpufreq/amd-pstate.h b/drivers/cpufreq/amd-pstate.h
>> index 19d405c6d805e..472044a1de43b 100644
>> --- a/drivers/cpufreq/amd-pstate.h
>> +++ b/drivers/cpufreq/amd-pstate.h
>> @@ -44,10 +44,6 @@ struct amd_aperf_mperf {
>> * priority.
>> * @min_limit_perf: Cached value of the performance corresponding to policy->min
>> * @max_limit_perf: Cached value of the performance corresponding to policy->max
>> - * @min_limit_freq: Cached value of policy->min (in khz)
>> - * @max_limit_freq: Cached value of policy->max (in khz)
>> - * @max_freq: the frequency (in khz) that mapped to highest_perf
>> - * @min_freq: the frequency (in khz) that mapped to lowest_perf
>> * @nominal_freq: the frequency (in khz) that mapped to nominal_perf
>> * @lowest_nonlinear_freq: the frequency (in khz) that mapped to lowest_nonlinear_perf
>> * @cur: Difference of Aperf/Mperf/tsc count between last and current sample
>> @@ -77,11 +73,7 @@ struct amd_cpudata {
>> u8 prefcore_ranking;
>> u8 min_limit_perf;
>> u8 max_limit_perf;
>> - u32 min_limit_freq;
>> - u32 max_limit_freq;
>>
>> - u32 max_freq;
>> - u32 min_freq;
>> u32 nominal_freq;
>> u32 lowest_nonlinear_freq;
>>
>
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