Define init_cpu_capacity_cppc() to use highest performance values
from _CPC objects to obtain and set maximum capacity information for
each CPU. acpi_cppc_processor_probe() is a good point at which to
trigger the initialization of CPU (u-arch) capacity values, as at this
point the highest performance values can be obtained from each CPU's
_CPC objects. Architectures can therefore use this functionality
through arch_init_invariance_cppc().
The performance scale used by CPPC is a unified scale for all CPUs in
the system. Therefore, by obtaining the raw highest performance values
from the _CPC objects, and normalizing them on the [0, 1024] capacity
scale, used by the task scheduler, we obtain the CPU capacity of each
CPU.
While an ACPI Notify(0x85) could alert about a change in the highest
performance value, which should in turn retrigger the CPU capacity
computations, this notification is not currently handled by the ACPI
processor driver. When supported, a call to arch_init_invariance_cppc()
would perform the update.
Signed-off-by: Ionela Voinescu <ionela.voinescu@xxxxxxx>
Cc: Sudeep Holla <sudeep.holla@xxxxxxx>
---
drivers/base/arch_topology.c | 39 +++++++++++++++++++++++++++++++++++
include/linux/arch_topology.h | 4 ++++
2 files changed, 43 insertions(+)
diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index c1179edc0f3b..f710d64f125b 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -291,6 +291,45 @@ bool __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu)
return !ret;
}
+#ifdef CONFIG_ACPI_CPPC_LIB
+#include <acpi/cppc_acpi.h>
+
+void init_cpu_capacity_cppc(void)
+{
+ struct cppc_perf_caps perf_caps;
+ int cpu;
+
+ if (likely(acpi_disabled || !acpi_cpc_valid()))
+ return;
+
+ raw_capacity = kcalloc(num_possible_cpus(), sizeof(*raw_capacity),
+ GFP_KERNEL);
+ if (!raw_capacity)
+ return;
+
+ for_each_possible_cpu(cpu) {
+ if (!cppc_get_perf_caps(cpu, &perf_caps)) {
+ raw_capacity[cpu] = perf_caps.highest_perf;
+ pr_debug("%s: CPU%d cpu_capacity=%u (raw).\n",
+ __func__, cpu, raw_capacity[cpu]);
+ } else {
+ pr_err("%s: CPU%d missing highest performance.\n",
+ __func__, cpu);
+ pr_err("%s: fallback to 1024 for all CPUs\n",
+ __func__);
+ goto exit;
+ }
+ }
+
+ topology_normalize_cpu_scale();
+ schedule_work(&update_topology_flags_work);
+ pr_debug("%s: cpu_capacity initialization done\n", __func__);
+
+exit:
+ free_raw_capacity();
+}
+#endif
+
#ifdef CONFIG_CPU_FREQ
static cpumask_var_t cpus_to_visit;
static void parsing_done_workfn(struct work_struct *work);
diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h
index f180240dc95f..fbd829c3b7f7 100644
--- a/include/linux/arch_topology.h
+++ b/include/linux/arch_topology.h
@@ -11,6 +11,10 @@
void topology_normalize_cpu_scale(void);
int topology_update_cpu_topology(void);
+#ifdef CONFIG_ACPI_CPPC_LIB
+void init_cpu_capacity_cppc(void);
+#endif
+
struct device_node;
bool topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu);
--
2.29.2.dirty
