Re: [patch 4/4] CPUIDLE: Add a poll_idle method into CPU_IDLE

[Len Brown <lenb@kernel.org>]

applied,
thanks,
-len

On Thursday 31 January 2008 20:35, venkatesh.pallipadi@intel.com wrote:
> 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>
> 
> Index: linux-2.6.25-rc/drivers/acpi/processor_idle.c
> ===================================================================
> --- linux-2.6.25-rc.orig/drivers/acpi/processor_idle.c
> +++ linux-2.6.25-rc/drivers/acpi/processor_idle.c
> @@ -1600,7 +1600,7 @@ 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;
> @@ -1659,6 +1659,8 @@ static int acpi_processor_setup_cpuidle(
>  		}
>  
>  		count++;
> +		if (count == CPUIDLE_STATE_MAX)
> +			break;
>  	}
>  
>  	dev->state_count = count;
> Index: linux-2.6.25-rc/drivers/cpuidle/cpuidle.c
> ===================================================================
> --- linux-2.6.25-rc.orig/drivers/cpuidle/cpuidle.c
> +++ linux-2.6.25-rc/drivers/cpuidle/cpuidle.c
> @@ -15,6 +15,7 @@
>  #include <linux/latency.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 cpuid
>  
>  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 cpuid
>  
>  	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))) {
> Index: linux-2.6.25-rc/include/linux/cpuidle.h
> ===================================================================
> --- linux-2.6.25-rc.orig/include/linux/cpuidle.h
> +++ linux-2.6.25-rc/include/linux/cpuidle.h
> @@ -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_go
>  
>  #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 */
> Index: linux-2.6.25-rc/arch/x86/Kconfig
> ===================================================================
> --- linux-2.6.25-rc.orig/arch/x86/Kconfig
> +++ linux-2.6.25-rc/arch/x86/Kconfig
> @@ -112,6 +112,9 @@ config GENERIC_TIME_VSYSCALL
>  	bool
>  	default X86_64
>  
> +config ARCH_HAS_CPU_RELAX
> +	def_bool y
> +
>  config ARCH_SUPPORTS_OPROFILE
>  	bool
>  	default y
>