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Date: Thu, 16 Jul 2015 15:08:56 -0700
From: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
To: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Cc: linux-pm@...r.kernel.org, "Rafael J. Wysocki" <rjw@...ysocki.net>,
linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
Kristen Carlson Accardi <kristen@...ux.intel.com>,
Len Brown <lenb@...nel.org>, Ethan Zhao <ethan.zhao@...cle.com>
Subject: Re: [PATCH RFC] intel_pstate: play well with frequency limits set
by acpi
On Thu, 2015-07-16 at 21:17 +0300, Konstantin Khlebnikov wrote:
> IPMI can control CPU P-states remotely: configuration is reported via
> common ACPI interface (_PPC/_PSS/etc). This patch adds required minimal
> support in intel_pstate to receive and use these P-state limits.
>
> * ignore limit of top state in _PPC: it lower than turbo boost frequency
> * register intel_pstate in acpi-processor to get states from _PSS
> * link acpi_processor_get_bios_limit: this adds attribute "bios_limit"
>
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
> ---
> drivers/acpi/processor_perflib.c | 3 +-
> drivers/cpufreq/intel_pstate.c | 57 ++++++++++++++++++++++++++++++++++++++
> 2 files changed, 59 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
> index cfc8aba72f86..781e328c9d5f 100644
> --- a/drivers/acpi/processor_perflib.c
> +++ b/drivers/acpi/processor_perflib.c
> @@ -98,7 +98,8 @@ static int acpi_processor_ppc_notifier(struct notifier_block *nb,
>
> ppc = (unsigned int)pr->performance_platform_limit;
>
> - if (ppc >= pr->performance->state_count)
> + /* Ignore limit of top state: it lower than turbo boost frequency */
> + if (!ppc || ppc >= pr->performance->state_count)
Why? Isn't the previous check enough?
> goto out;
>
> cpufreq_verify_within_limits(policy, 0,
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index 15ada47bb720..4a34ddf4fa73 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -26,6 +26,7 @@
> #include <linux/fs.h>
> #include <linux/debugfs.h>
> #include <linux/acpi.h>
> +#include <acpi/processor.h>
> #include <linux/vmalloc.h>
> #include <trace/events/power.h>
>
> @@ -113,6 +114,9 @@ struct cpudata {
> u64 prev_mperf;
> u64 prev_tsc;
> struct sample sample;
> +#ifdef CONFIG_ACPI_PROCESSOR
> + struct acpi_processor_performance acpi_data;
> +#endif
> };
>
> static struct cpudata **all_cpu_data;
> @@ -145,6 +149,7 @@ static int hwp_active;
>
> struct perf_limits {
> int no_turbo;
> + int no_acpi;
> int turbo_disabled;
> int max_perf_pct;
> int min_perf_pct;
> @@ -158,6 +163,7 @@ struct perf_limits {
>
> static struct perf_limits limits = {
> .no_turbo = 0,
> + .no_acpi = !IS_ENABLED(CONFIG_ACPI_PROCESSOR),
> .turbo_disabled = 0,
> .max_perf_pct = 100,
> .max_perf = int_tofp(1),
> @@ -449,6 +455,18 @@ static ssize_t store_min_perf_pct(struct kobject *a, struct attribute *b,
> return count;
> }
>
> +static ssize_t store_no_acpi(struct kobject *a, struct attribute *b,
> + const char *buf, size_t count)
> +{
> +#ifdef CONFIG_ACPI_PROCESSOR
> + return kstrtouint(buf, 0, &limits.no_acpi) ?: count;
> +#else
> + return -ENODEV;
> +#endif
> +}
> +show_one(no_acpi, no_acpi);
> +define_one_global_rw(no_acpi);
> +
> show_one(max_perf_pct, max_perf_pct);
> show_one(min_perf_pct, min_perf_pct);
>
> @@ -460,6 +478,7 @@ define_one_global_ro(num_pstates);
>
> static struct attribute *intel_pstate_attributes[] = {
> &no_turbo.attr,
> + &no_acpi.attr,
> &max_perf_pct.attr,
> &min_perf_pct.attr,
> &turbo_pct.attr,
> @@ -1049,6 +1068,38 @@ static int intel_pstate_cpu_init(struct cpufreq_policy *policy)
> policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
> cpumask_set_cpu(policy->cpu, policy->cpus);
>
> +#ifdef CONFIG_ACPI_PROCESSOR
> + if (!limits.no_acpi) {
> + /*
> + * Minimum necessary to get acpi_processor_ppc_notifier() and
> + * acpi_processor_get_bios_limit() working.
> + */
> + if (!zalloc_cpumask_var(&cpu->acpi_data.shared_cpu_map,
> + GFP_KERNEL))
> + rc = -ENOMEM;
> + else
> + rc = acpi_processor_register_performance(
> + &cpu->acpi_data, policy->cpu);
> + if (rc) {
> + pr_err("intel_pstate: acpi init failed: %d\n", rc);
> + free_cpumask_var(cpu->acpi_data.shared_cpu_map);
> + limits.no_acpi = 1;
> + }
> + }
> +#endif
> + return 0;
> +}
> +
> +static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)
> +{
> +#ifdef CONFIG_ACPI_PROCESSOR
> + struct cpudata *cpu = all_cpu_data[policy->cpu];
> +
> + if (cpu->acpi_data.state_count)
> + acpi_processor_unregister_performance(&cpu->acpi_data,
> + policy->cpu);
> + free_cpumask_var(cpu->acpi_data.shared_cpu_map);
> +#endif
> return 0;
> }
>
> @@ -1057,7 +1108,11 @@ static struct cpufreq_driver intel_pstate_driver = {
> .verify = intel_pstate_verify_policy,
> .setpolicy = intel_pstate_set_policy,
> .get = intel_pstate_get,
> +#ifdef CONFIG_ACPI_PROCESSOR
> + .bios_limit = acpi_processor_get_bios_limit,
> +#endif
> .init = intel_pstate_cpu_init,
> + .exit = intel_pstate_cpu_exit,
> .stop_cpu = intel_pstate_stop_cpu,
> .name = "intel_pstate",
> };
> @@ -1286,6 +1341,8 @@ static int __init intel_pstate_setup(char *str)
> force_load = 1;
> if (!strcmp(str, "hwp_only"))
> hwp_only = 1;
> + if (!strcmp(str, "no_acpi"))
> + limits.no_acpi = 1;
> return 0;
> }
> early_param("intel_pstate", intel_pstate_setup);
>
_PPC is index into _PSS. Since intel P state doesn't follow _PSS, the
states may not be 1:1 matching. So we have to harmonize them.
> --
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