| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <161082be-0df8-0128-bc77-58aee8d43bf6@huawei.com>
Date: Thu, 21 May 2020 14:25:26 +0800
From: Xiongfeng Wang <wangxiongfeng2@...wei.com>
To: Viresh Kumar <viresh.kumar@...aro.org>
CC: <rjw@...ysocki.net>, <Souvik.Chakravarty@....com>,
<Thanu.Rangarajan@....com>, <Sudeep.Holla@....com>,
<guohanjun@...wei.com>, <john.garry@...wei.com>,
<jonathan.cameron@...wei.com>, <linux-pm@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH v3 2/2] CPPC: add support for SW BOOST
Hi Viresh,
On 2020/5/20 13:00, Viresh Kumar wrote:
> On 19-05-20, 19:41, Xiongfeng Wang wrote:
>> To add SW BOOST support for CPPC, we need to get the max frequency of
>> boost mode and non-boost mode. ACPI spec 6.2 section 8.4.7.1 describe
>> the following two CPC registers.
>>
>> "Highest performance is the absolute maximum performance an individual
>> processor may reach, assuming ideal conditions. This performance level
>> may not be sustainable for long durations, and may only be achievable if
>> other platform components are in a specific state; for example, it may
>> require other processors be in an idle state.
>>
>> Nominal Performance is the maximum sustained performance level of the
>> processor, assuming ideal operating conditions. In absence of an
>> external constraint (power, thermal, etc.) this is the performance level
>> the platform is expected to be able to maintain continuously. All
>> processors are expected to be able to sustain their nominal performance
>> state simultaneously."
>>
>> To add SW BOOST support for CPPC, we can use Highest Performance as the
>> max performance in boost mode and Nominal Performance as the max
>> performance in non-boost mode. If the Highest Performance is greater
>> than the Nominal Performance, we assume SW BOOST is supported.
>>
>> The current CPPC driver does not support SW BOOST and use 'Highest
>> Performance' as the max performance the CPU can achieve. 'Nominal
>> Performance' is used to convert 'performance' to 'frequency'. That
>> means, if firmware enable boost and provide a value for Highest
>> Performance which is greater than Nominal Performance, boost feature is
>> enabled by default.
>>
>> Because SW BOOST is disabled by default, so, after this patch, boost
>> feature is disabled by default even if boost is enabled by firmware.
>>
>> Signed-off-by: Xiongfeng Wang <wangxiongfeng2@...wei.com>
>> ---
>> drivers/cpufreq/cppc_cpufreq.c | 39 +++++++++++++++++++++++++++++++++++++--
>> 1 file changed, 37 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
>> index bda0b24..792ed9e 100644
>> --- a/drivers/cpufreq/cppc_cpufreq.c
>> +++ b/drivers/cpufreq/cppc_cpufreq.c
>> @@ -37,6 +37,7 @@
>> * requested etc.
>> */
>> static struct cppc_cpudata **all_cpu_data;
>> +static bool boost_supported;
>>
>> struct cppc_workaround_oem_info {
>> char oem_id[ACPI_OEM_ID_SIZE + 1];
>> @@ -310,7 +311,7 @@ static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
>> * Section 8.4.7.1.1.5 of ACPI 6.1 spec)
>> */
>> policy->min = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.lowest_nonlinear_perf);
>> - policy->max = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.highest_perf);
>> + policy->max = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.nominal_perf);
>>
>> /*
>> * Set cpuinfo.min_freq to Lowest to make the full range of performance
>> @@ -318,7 +319,7 @@ static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
>> * nonlinear perf
>> */
>> policy->cpuinfo.min_freq = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.lowest_perf);
>> - policy->cpuinfo.max_freq = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.highest_perf);
>> + policy->cpuinfo.max_freq = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.nominal_perf);
>>
>> policy->transition_delay_us = cppc_cpufreq_get_transition_delay_us(cpu_num);
>> policy->shared_type = cpu->shared_type;
>> @@ -343,6 +344,13 @@ static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
>>
>> cpu->cur_policy = policy;
>>
>> + /*
>> + * If 'highest_perf' is greater than 'nominal_perf', we assume CPU Boost
>> + * is supported.
>> + */
>> + if (cpu->perf_caps.highest_perf > cpu->perf_caps.nominal_perf)
>> + boost_supported = true;
>> +
>> /* Set policy->cur to max now. The governors will adjust later. */
>> policy->cur = cppc_cpufreq_perf_to_khz(cpu,
>> cpu->perf_caps.highest_perf);
>> @@ -410,6 +418,32 @@ static unsigned int cppc_cpufreq_get_rate(unsigned int cpunum)
>> return cppc_get_rate_from_fbctrs(cpu, fb_ctrs_t0, fb_ctrs_t1);
>> }
>>
>> +static int cppc_cpufreq_set_boost(struct cpufreq_policy *policy, int state)
>> +{
>> + struct cppc_cpudata *cpudata;
>> + int ret = 0;
>
> No need to initialize this.
I will change it in the next version.
Thanks for your advice. I will add your 'Suggested-by' for these two patches.
Thanks,
Xiongfeng
>
>> +
>> + if (!boost_supported) {
>> + pr_err("BOOST not supported by CPU or firmware\n");
>> + return -EINVAL;
>> + }
>> +
>> + cpudata = all_cpu_data[policy->cpu];
>> + if (state)
>> + policy->max = cppc_cpufreq_perf_to_khz(cpudata,
>> + cpudata->perf_caps.highest_perf);
>> + else
>> + policy->max = cppc_cpufreq_perf_to_khz(cpudata,
>> + cpudata->perf_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;
>> +
>> + return 0;
>> +}
>> +
>> static struct cpufreq_driver cppc_cpufreq_driver = {
>> .flags = CPUFREQ_CONST_LOOPS,
>> .verify = cppc_verify_policy,
>> @@ -417,6 +451,7 @@ static unsigned int cppc_cpufreq_get_rate(unsigned int cpunum)
>> .get = cppc_cpufreq_get_rate,
>> .init = cppc_cpufreq_cpu_init,
>> .stop_cpu = cppc_cpufreq_stop_cpu,
>> + .set_boost = cppc_cpufreq_set_boost,
>> .name = "cppc_cpufreq",
>> };
>>
>> --
>> 1.7.12.4
>
Powered by blists - more mailing lists