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intel_idle: Use ACPI _CST for processor models without C-state tables

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Modify the intel_idle driver to get the C-states information from ACPI
_CST if the processor model is not recognized by it.

The processor is still required to support MWAIT and the information
from ACPI _CST will only be used if all of the C-states listed by
_CST are of the ACPI_CSTATE_FFH type (which means that they are
expected to be entered via MWAIT).

Moreover, the driver assumes that the _CST information is the same
for all CPUs in the system, so it is sufficient to evaluate _CST for
one of them and extract the common list of C-states from there.
Also _CST is evaluated once at the system initialization time and
the driver does not respond to _CST change notifications (that can
be changed in the future).

The main functional difference between intel_idle with this change
and the ACPI processor driver is that the former sets the target
residency to be equal to the exit latency (provided by _CST) for
C1-type C-states and to 3 times the exit latency value for the other
C-state types, whereas the latter obtains the target residency by
multiplying the exit latency by the same number (2 by default) for
all C-state types.  Therefore it is expected that in general using
the former instead of the latter on the same system will lead to
improved energy-efficiency.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Rafael J. Wysocki 2019-12-13 09:56:01 +01:00
parent 9f3d6daf61
commit 18734958e9
1 changed files with 162 additions and 28 deletions
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190
drivers/idle/intel_idle.c
View file

@ -41,6 +41,7 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/acpi.h>
#include <linux/kernel.h>
#include <linux/cpuidle.h>
#include <linux/tick.h>
@ -1111,6 +1112,129 @@ static const struct x86_cpu_id intel_idle_ids[] __initconst = {
{}
};
#define INTEL_CPU_FAM6_MWAIT \
{ X86_VENDOR_INTEL, 6, X86_MODEL_ANY, X86_FEATURE_MWAIT, 0 }
static const struct x86_cpu_id intel_mwait_ids[] __initconst = {
INTEL_CPU_FAM6_MWAIT,
{}
};
static bool intel_idle_max_cstate_reached(int cstate)
{
if (cstate + 1 > max_cstate) {
pr_info("max_cstate %d reached\n", max_cstate);
return true;
}
return false;
}
#ifdef CONFIG_ACPI_PROCESSOR_CSTATE
#include <acpi/processor.h>
static struct acpi_processor_power acpi_state_table;
/**
* intel_idle_cst_usable - Check if the _CST information can be used.
*
* Check if all of the C-states listed by _CST in the max_cstate range are
* ACPI_CSTATE_FFH, which means that they should be entered via MWAIT.
*/
static bool intel_idle_cst_usable(void)
{
int cstate, limit;
limit = min_t(int, min_t(int, CPUIDLE_STATE_MAX, max_cstate + 1),
acpi_state_table.count);
for (cstate = 1; cstate < limit; cstate++) {
struct acpi_processor_cx *cx = &acpi_state_table.states[cstate];
if (cx->entry_method != ACPI_CSTATE_FFH)
return false;
}
return true;
}
static bool intel_idle_acpi_cst_extract(void)
{
unsigned int cpu;
for_each_possible_cpu(cpu) {
struct acpi_processor *pr = per_cpu(processors, cpu);
if (!pr)
continue;
if (acpi_processor_evaluate_cst(pr->handle, cpu, &acpi_state_table))
continue;
acpi_state_table.count++;
if (!intel_idle_cst_usable())
continue;
if (!acpi_processor_claim_cst_control()) {
acpi_state_table.count = 0;
return false;
}
return true;
}
pr_debug("ACPI _CST not found or not usable\n");
return false;
}
static void intel_idle_init_cstates_acpi(struct cpuidle_driver *drv)
{
int cstate, limit = min_t(int, CPUIDLE_STATE_MAX, acpi_state_table.count);
/*
* If limit > 0, intel_idle_cst_usable() has returned 'true', so all of
* the interesting states are ACPI_CSTATE_FFH.
*/
for (cstate = 1; cstate < limit; cstate++) {
struct acpi_processor_cx *cx;
struct cpuidle_state *state;
if (intel_idle_max_cstate_reached(cstate))
break;
cx = &acpi_state_table.states[cstate];
state = &drv->states[drv->state_count++];
snprintf(state->name, CPUIDLE_NAME_LEN, "C%d_ACPI", cstate);
strlcpy(state->desc, cx->desc, CPUIDLE_DESC_LEN);
state->exit_latency = cx->latency;
/*
* For C1-type C-states use the same number for both the exit
* latency and target residency, because that is the case for
* C1 in the majority of the static C-states tables above.
* For the other types of C-states, however, set the target
* residency to 3 times the exit latency which should lead to
* a reasonable balance between energy-efficiency and
* performance in the majority of interesting cases.
*/
state->target_residency = cx->latency;
if (cx->type > ACPI_STATE_C1)
state->target_residency *= 3;
state->flags = MWAIT2flg(cx->address);
if (cx->type > ACPI_STATE_C2)
state->flags |= CPUIDLE_FLAG_TLB_FLUSHED;
state->enter = intel_idle;
state->enter_s2idle = intel_idle_s2idle;
}
}
#else /* !CONFIG_ACPI_PROCESSOR_CSTATE */
static inline bool intel_idle_acpi_cst_extract(void) { return false; }
static inline void intel_idle_init_cstates_acpi(struct cpuidle_driver *drv) { }
#endif /* !CONFIG_ACPI_PROCESSOR_CSTATE */
/*
* intel_idle_probe()
*/
@ -1125,17 +1249,15 @@ static int __init intel_idle_probe(void)
}
id = x86_match_cpu(intel_idle_ids);
if (!id) {
if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
boot_cpu_data.x86 == 6)
pr_debug("does not run on family %d model %d\n",
boot_cpu_data.x86, boot_cpu_data.x86_model);
return -ENODEV;
}
if (!boot_cpu_has(X86_FEATURE_MWAIT)) {
pr_debug("Please enable MWAIT in BIOS SETUP\n");
return -ENODEV;
if (id) {
if (!boot_cpu_has(X86_FEATURE_MWAIT)) {
pr_debug("Please enable MWAIT in BIOS SETUP\n");
return -ENODEV;
}
} else {
id = x86_match_cpu(intel_mwait_ids);
if (!id)
return -ENODEV;
}
if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
@ -1151,7 +1273,10 @@ static int __init intel_idle_probe(void)
pr_debug("MWAIT substates: 0x%x\n", mwait_substates);
icpu = (const struct idle_cpu *)id->driver_data;
cpuidle_state_table = icpu->state_table;
if (icpu)
cpuidle_state_table = icpu->state_table;
else if (!intel_idle_acpi_cst_extract())
return -ENODEV;
pr_debug("v" INTEL_IDLE_VERSION " model 0x%X\n",
boot_cpu_data.x86_model);
@ -1333,32 +1458,20 @@ static void intel_idle_state_table_update(void)
}
}
/*
* intel_idle_cpuidle_driver_init()
* allocate, initialize cpuidle_states
*/
static void __init intel_idle_cpuidle_driver_init(void)
static void intel_idle_init_cstates_icpu(struct cpuidle_driver *drv)
{
int cstate;
struct cpuidle_driver *drv = &intel_idle_driver;
intel_idle_state_table_update();
cpuidle_poll_state_init(drv);
drv->state_count = 1;
for (cstate = 0; cstate < CPUIDLE_STATE_MAX; ++cstate) {
unsigned int mwait_hint;
if (intel_idle_max_cstate_reached(cstate))
break;
if (!cpuidle_state_table[cstate].enter &&
!cpuidle_state_table[cstate].enter_s2idle)
break;
if (cstate + 1 > max_cstate) {
pr_info("max_cstate %d reached\n", max_cstate);
break;
}
/* If marked as unusable, skip this state. */
if (cpuidle_state_table[cstate].flags & CPUIDLE_FLAG_UNUSABLE) {
pr_debug("state %s is disabled\n",
@ -1380,6 +1493,24 @@ static void __init intel_idle_cpuidle_driver_init(void)
}
}
/*
* intel_idle_cpuidle_driver_init()
* allocate, initialize cpuidle_states
*/
static void __init intel_idle_cpuidle_driver_init(void)
{
struct cpuidle_driver *drv = &intel_idle_driver;
intel_idle_state_table_update();
cpuidle_poll_state_init(drv);
drv->state_count = 1;
if (icpu)
intel_idle_init_cstates_icpu(drv);
else
intel_idle_init_cstates_acpi(drv);
}
/*
* intel_idle_cpu_init()
@ -1398,6 +1529,9 @@ static int intel_idle_cpu_init(unsigned int cpu)
return -EIO;
}
if (!icpu)
return 0;
if (icpu->auto_demotion_disable_flags)
auto_demotion_disable();