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cpuidle: Add a poll_idle method 

Add a default poll idle state with 0 latency. Provides an option to users
to use poll_idle by using 0 as the latency requirement.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
venkatesh.pallipadi@intel.com 2008-01-31 17:35:06 -08:00 committed by Len Brown
parent 9b12e18cdc
commit 9a0b841586
4 changed files with 57 additions and 4 deletions
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3
arch/x86/Kconfig
View File

@ -105,6 +105,9 @@ config GENERIC_TIME_VSYSCALL
bool
default X86_64
config ARCH_HAS_CPU_RELAX
def_bool y
config HAVE_SETUP_PER_CPU_AREA
def_bool X86_64

4
drivers/acpi/processor_idle.c
View File

@ -1628,7 +1628,7 @@ struct cpuidle_driver acpi_idle_driver = {
*/
static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
{
int i, count = 0;
int i, count = CPUIDLE_DRIVER_STATE_START;
struct acpi_processor_cx *cx;
struct cpuidle_state *state;
struct cpuidle_device *dev = &pr->power.dev;
@ -1687,6 +1687,8 @@ static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
}
count++;
if (count == CPUIDLE_STATE_MAX)
break;
}
dev->state_count = count;

41
drivers/cpuidle/cpuidle.c
View File

@ -15,6 +15,7 @@
#include <linux/pm_qos_params.h>
#include <linux/cpu.h>
#include <linux/cpuidle.h>
#include <linux/ktime.h>
#include "cpuidle.h"
@ -180,6 +181,44 @@ void cpuidle_disable_device(struct cpuidle_device *dev)
EXPORT_SYMBOL_GPL(cpuidle_disable_device);
#ifdef CONFIG_ARCH_HAS_CPU_RELAX
static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st)
{
ktime_t t1, t2;
s64 diff;
int ret;
t1 = ktime_get();
local_irq_enable();
while (!need_resched())
cpu_relax();
t2 = ktime_get();
diff = ktime_to_us(ktime_sub(t2, t1));
if (diff > INT_MAX)
diff = INT_MAX;
ret = (int) diff;
return ret;
}
static void poll_idle_init(struct cpuidle_device *dev)
{
struct cpuidle_state *state = &dev->states[0];
cpuidle_set_statedata(state, NULL);
snprintf(state->name, CPUIDLE_NAME_LEN, "C0 (poll idle)");
state->exit_latency = 0;
state->target_residency = 0;
state->power_usage = -1;
state->flags = CPUIDLE_FLAG_POLL | CPUIDLE_FLAG_TIME_VALID;
state->enter = poll_idle;
}
#else
static void poll_idle_init(struct cpuidle_device *dev) {}
#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
/**
* cpuidle_register_device - registers a CPU's idle PM feature
* @dev: the cpu
@ -198,6 +237,8 @@ int cpuidle_register_device(struct cpuidle_device *dev)
mutex_lock(&cpuidle_lock);
poll_idle_init(dev);
per_cpu(cpuidle_devices, dev->cpu) = dev;
list_add(&dev->device_list, &cpuidle_detected_devices);
if ((ret = cpuidle_add_sysfs(sys_dev))) {

13
include/linux/cpuidle.h
View File

@ -46,9 +46,10 @@ struct cpuidle_state {
/* Idle State Flags */
#define CPUIDLE_FLAG_TIME_VALID (0x01) /* is residency time measurable? */
#define CPUIDLE_FLAG_CHECK_BM (0x02) /* BM activity will exit state */
#define CPUIDLE_FLAG_SHALLOW (0x10) /* low latency, minimal savings */
#define CPUIDLE_FLAG_BALANCED (0x20) /* medium latency, moderate savings */
#define CPUIDLE_FLAG_DEEP (0x40) /* high latency, large savings */
#define CPUIDLE_FLAG_POLL (0x10) /* no latency, no savings */
#define CPUIDLE_FLAG_SHALLOW (0x20) /* low latency, minimal savings */
#define CPUIDLE_FLAG_BALANCED (0x40) /* medium latency, moderate savings */
#define CPUIDLE_FLAG_DEEP (0x80) /* high latency, large savings */
#define CPUIDLE_DRIVER_FLAGS_MASK (0xFFFF0000)
@ -178,4 +179,10 @@ static inline void cpuidle_unregister_governor(struct cpuidle_governor *gov) { }
#endif
#ifdef CONFIG_ARCH_HAS_CPU_RELAX
#define CPUIDLE_DRIVER_STATE_START 1
#else
#define CPUIDLE_DRIVER_STATE_START 0
#endif
#endif /* _LINUX_CPUIDLE_H */