[PATCH v2 8/8] cpufreq: intel_pstate: Use CPPC to get max performance

Srinivas Pandruvada
2016-09-01T21:13:26Z

This change uses acpi cppc_lib interface to get CPPC performance limits.
Once CPPC limits of all online cores are read, first check if there is
difference in max performance. If there is a difference, then the
scheduler interface is called to update per cpu priority. After updating
priority of all current cpus, the itmt feature is enabled.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
---
drivers/cpufreq/Kconfig.x86 | 1 +
drivers/cpufreq/intel_pstate.c | 75 ++++++++++++++++++++++++++++++++++++++++--
2 files changed, 73 insertions(+), 3 deletions(-)

diff --git a/drivers/cpufreq/Kconfig.x86 b/drivers/cpufreq/Kconfig.x86
index adbd1de..3328c6b 100644
--- a/drivers/cpufreq/Kconfig.x86
+++ b/drivers/cpufreq/Kconfig.x86
@@ -6,6 +6,7 @@ config X86_INTEL_PSTATE
bool "Intel P state control"
depends on X86
select ACPI_PROCESSOR if ACPI
+ select ACPI_CPPC_LIB if X86_64 && ACPI
help
This driver provides a P state for Intel core processors.
The driver implements an internal governor and will become
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index bdbe936..a0bf244 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -44,6 +44,7 @@

#ifdef CONFIG_ACPI
#include <acpi/processor.h>
+#include <acpi/cppc_acpi.h>
#endif

#define FRAC_BITS 8
@@ -193,6 +194,8 @@ struct _pid {
* @sample: Storage for storing last Sample data
* @acpi_perf_data: Stores ACPI perf information read from _PSS
* @valid_pss_table: Set to true for valid ACPI _PSS entries found
+ * @cppc_data: Stores CPPC information for HWP capable CPUs
+ * @valid_cppc_table: Set to true for valid CPPC entries are found
*
* This structure stores per CPU instance data for all CPUs.
*/
@@ -215,6 +218,8 @@ struct cpudata {
#ifdef CONFIG_ACPI
struct acpi_processor_performance acpi_perf_data;
bool valid_pss_table;
+ struct cppc_cpudata *cppc_data;
+ bool valid_cppc_table;
#endif
};

@@ -361,6 +366,15 @@ static struct perf_limits *limits = &powersave_limits;
#endif

#ifdef CONFIG_ACPI
+static cpumask_t cppc_rd_cpu_mask;
+
+/* Call set_sched_itmt from a work function to be able to use hotplug locks */
+static void intel_pstste_sched_itmt_work_fn(struct work_struct *work)
+{
+ set_sched_itmt(true);
+}
+
+static DECLARE_WORK(sched_itmt_work, intel_pstste_sched_itmt_work_fn);

static bool intel_pstate_get_ppc_enable_status(void)
{
@@ -377,14 +391,63 @@ static void intel_pstate_init_acpi_perf_limits(struct cpufreq_policy *policy)
int ret;
int i;

- if (hwp_active)
+ cpu = all_cpu_data[policy->cpu];
+
+ if (hwp_active) {
+ struct cppc_perf_caps *perf_caps;
+
+ cpu->cppc_data = kzalloc(sizeof(struct cppc_cpudata),
+ GFP_KERNEL);
+ if (!cpu->cppc_data)
+ return;
+
+ perf_caps = &cpu->cppc_data->perf_caps;
+ ret = cppc_get_perf_caps(policy->cpu, perf_caps);
+ if (ret) {
+ kfree(cpu->cppc_data);
+ return;
+ }
+
+ cpu->valid_cppc_table = true;
+ pr_debug("cpu:%d H:0x%x N:0x%x L:0x%x\n", policy->cpu,
+ perf_caps->highest_perf, perf_caps->nominal_perf,
+ perf_caps->lowest_perf);
+
+ cpumask_set_cpu(policy->cpu, &cppc_rd_cpu_mask);
+ if (cpumask_subset(topology_core_cpumask(policy->cpu),
+ &cppc_rd_cpu_mask)) {
+ int cpu_index;
+ int max_prio;
+ bool itmt_support = false;
+
+ cpu = all_cpu_data[0];
+ max_prio = cpu->cppc_data->perf_caps.highest_perf;
+ for_each_cpu(cpu_index, &cppc_rd_cpu_mask) {
+ cpu = all_cpu_data[cpu_index];
+ perf_caps = &cpu->cppc_data->perf_caps;
+ if (max_prio != perf_caps->highest_perf) {
+ itmt_support = true;
+ break;
+ }
+ }
+
+ if (!itmt_support)
+ return;
+
+ for_each_cpu(cpu_index, &cppc_rd_cpu_mask) {
+ cpu = all_cpu_data[cpu_index];
+ perf_caps = &cpu->cppc_data->perf_caps;
+ sched_set_itmt_core_prio(
+ perf_caps->highest_perf, cpu_index);
+ }
+ schedule_work(&sched_itmt_work);
+ }
return;
+ }

if (!intel_pstate_get_ppc_enable_status())
return;

- cpu = all_cpu_data[policy->cpu];
-
ret = acpi_processor_register_performance(&cpu->acpi_perf_data,
policy->cpu);
if (ret)
@@ -444,6 +507,12 @@ static void intel_pstate_exit_perf_limits(struct cpufreq_policy *policy)
struct cpudata *cpu;

cpu = all_cpu_data[policy->cpu];
+
+ if (cpu->valid_cppc_table) {
+ cpumask_clear_cpu(policy->cpu, &cppc_rd_cpu_mask);
+ kfree(cpu->cppc_data);
+ }
+
if (!cpu->valid_pss_table)
return;

--
2.7.4