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>

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>
venkatesh.pallipadi@intel.com · Len Brown
1 parent 9b12e18cdc
Showing 4 changed files with 57 additions and 4 deletions Side-by-side Diff
arch/x86/Kconfig
drivers/acpi/processor_idle.c
drivers/cpuidle/cpuidle.c
include/linux/cpuidle.h
@@ -105,6 +105,9 @@
 	bool
 	default X86_64
  
+config ARCH_HAS_CPU_RELAX
+	def_bool y
+
 config HAVE_SETUP_PER_CPU_AREA
 	def_bool X86_64
  
@@ -1628,7 +1628,7 @@
  */
 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 @@
 		}
  
 		count++;
+		if (count == CPUIDLE_STATE_MAX)
+			break;
 	}
  
 	dev->state_count = count;
@@ -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 @@
  
 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
@@ -197,6 +236,8 @@
 	init_completion(&dev->kobj_unregister);
  
 	mutex_lock(&cpuidle_lock);
+
+	poll_idle_init(dev);
  
 	per_cpu(cpuidle_devices, dev->cpu) = dev;
 	list_add(&dev->device_list, &cpuidle_detected_devices);
@@ -46,9 +46,10 @@
 /* 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)
  
@@ -176,6 +177,12 @@
 {return 0;}
 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 */
...	...	@@ -105,6 +105,9 @@
105	105	bool
106	106	default X86_64
107	107
	108	+config ARCH_HAS_CPU_RELAX
	109	+ def_bool y
	110	+
108	111	config HAVE_SETUP_PER_CPU_AREA
109	112	def_bool X86_64
110	113
...	...	@@ -1628,7 +1628,7 @@
1628	1628	*/
1629	1629	static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
1630	1630	{
1631		- int i, count = 0;
	1631	+ int i, count = CPUIDLE_DRIVER_STATE_START;
1632	1632	struct acpi_processor_cx *cx;
1633	1633	struct cpuidle_state *state;
1634	1634	struct cpuidle_device *dev = &pr->power.dev;
...	...	@@ -1687,6 +1687,8 @@
1687	1687	}
1688	1688
1689	1689	count++;
	1690	+ if (count == CPUIDLE_STATE_MAX)
	1691	+ break;
1690	1692	}
1691	1693
1692	1694	dev->state_count = count;
...	...	@@ -15,6 +15,7 @@
15	15	#include <linux/pm_qos_params.h>
16	16	#include <linux/cpu.h>
17	17	#include <linux/cpuidle.h>
	18	+#include <linux/ktime.h>
18	19
19	20	#include "cpuidle.h"
20	21
...	...	@@ -180,6 +181,44 @@
180	181
181	182	EXPORT_SYMBOL_GPL(cpuidle_disable_device);
182	183
	184	+#ifdef CONFIG_ARCH_HAS_CPU_RELAX
	185	+static int poll_idle(struct cpuidle_device dev, struct cpuidle_state st)
	186	+{
	187	+ ktime_t t1, t2;
	188	+ s64 diff;
	189	+ int ret;
	190	+
	191	+ t1 = ktime_get();
	192	+ local_irq_enable();
	193	+ while (!need_resched())
	194	+ cpu_relax();
	195	+
	196	+ t2 = ktime_get();
	197	+ diff = ktime_to_us(ktime_sub(t2, t1));
	198	+ if (diff > INT_MAX)
	199	+ diff = INT_MAX;
	200	+
	201	+ ret = (int) diff;
	202	+ return ret;
	203	+}
	204	+
	205	+static void poll_idle_init(struct cpuidle_device *dev)
	206	+{
	207	+ struct cpuidle_state *state = &dev->states[0];
	208	+
	209	+ cpuidle_set_statedata(state, NULL);
	210	+
	211	+ snprintf(state->name, CPUIDLE_NAME_LEN, "C0 (poll idle)");
	212	+ state->exit_latency = 0;
	213	+ state->target_residency = 0;
	214	+ state->power_usage = -1;
	215	+ state->flags = CPUIDLE_FLAG_POLL \| CPUIDLE_FLAG_TIME_VALID;
	216	+ state->enter = poll_idle;
	217	+}
	218	+#else
	219	+static void poll_idle_init(struct cpuidle_device *dev) {}
	220	+#endif /* CONFIG_ARCH_HAS_CPU_RELAX */
	221	+
183	222	/**
184	223	* cpuidle_register_device - registers a CPU's idle PM feature
185	224	* @dev: the cpu
...	...	@@ -197,6 +236,8 @@
197	236	init_completion(&dev->kobj_unregister);
198	237
199	238	mutex_lock(&cpuidle_lock);
	239	+
	240	+ poll_idle_init(dev);
200	241
201	242	per_cpu(cpuidle_devices, dev->cpu) = dev;
202	243	list_add(&dev->device_list, &cpuidle_detected_devices);
...	...	@@ -46,9 +46,10 @@
46	46	/* Idle State Flags */
47	47	#define CPUIDLE_FLAG_TIME_VALID (0x01) /* is residency time measurable? */
48	48	#define CPUIDLE_FLAG_CHECK_BM (0x02) /* BM activity will exit state */
49		-#define CPUIDLE_FLAG_SHALLOW (0x10) /* low latency, minimal savings */
50		-#define CPUIDLE_FLAG_BALANCED (0x20) /* medium latency, moderate savings */
51		-#define CPUIDLE_FLAG_DEEP (0x40) /* high latency, large savings */
	49	+#define CPUIDLE_FLAG_POLL (0x10) /* no latency, no savings */
	50	+#define CPUIDLE_FLAG_SHALLOW (0x20) /* low latency, minimal savings */
	51	+#define CPUIDLE_FLAG_BALANCED (0x40) /* medium latency, moderate savings */
	52	+#define CPUIDLE_FLAG_DEEP (0x80) /* high latency, large savings */
52	53
53	54	#define CPUIDLE_DRIVER_FLAGS_MASK (0xFFFF0000)
54	55
...	...	@@ -176,6 +177,12 @@
176	177	{return 0;}
177	178	static inline void cpuidle_unregister_governor(struct cpuidle_governor *gov) { }
178	179
	180	+#endif
	181	+
	182	+#ifdef CONFIG_ARCH_HAS_CPU_RELAX
	183	+#define CPUIDLE_DRIVER_STATE_START 1
	184	+#else
	185	+#define CPUIDLE_DRIVER_STATE_START 0
179	186	#endif
180	187
181	188	#endif /* _LINUX_CPUIDLE_H */