[patch 2/5] cpuidle: add get_poll_time callback

Marcelo Tosatti
2019-06-13T22:55:13Z

Add a "get_poll_time" callback to the cpuidle_governor structure,
and change poll state to poll for that amount of time.

Provide a default method for it, while allowing individual governors
to override it.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

---
drivers/cpuidle/cpuidle.c | 40 ++++++++++++++++++++++++++++++++++++++++
drivers/cpuidle/poll_state.c | 11 ++---------
include/linux/cpuidle.h | 8 ++++++++
3 files changed, 50 insertions(+), 9 deletions(-)

Index: linux-2.6.git/drivers/cpuidle/cpuidle.c
===================================================================
--- linux-2.6.git.orig/drivers/cpuidle/cpuidle.c 2019-06-13 17:57:33.111185824 -0400
+++ linux-2.6.git/drivers/cpuidle/cpuidle.c 2019-06-13 18:09:48.158500660 -0400
@@ -362,6 +362,46 @@
}

/**
+ * cpuidle_default_poll_time - default routine used to return poll time
+ * governors can override it if necessary
+ *
+ * @drv: the cpuidle driver tied with the cpu
+ * @dev: the cpuidle device
+ *
+ */
+static u64 cpuidle_default_poll_time(struct cpuidle_driver *drv,
+ struct cpuidle_device *dev)
+{
+ int i;
+
+ for (i = 1; i < drv->state_count; i++) {
+ if (drv->states[i].disabled || dev->states_usage[i].disable)
+ continue;
+
+ return (u64)drv->states[i].target_residency * NSEC_PER_USEC;
+ }
+
+ return TICK_NSEC;
+}
+
+/**
+ * cpuidle_get_poll_time - tell the polling driver how much time to poll,
+ * in nanoseconds.
+ *
+ * @drv: the cpuidle driver tied with the cpu
+ * @dev: the cpuidle device
+ *
+ */
+u64 cpuidle_get_poll_time(struct cpuidle_driver *drv,
+ struct cpuidle_device *dev)
+{
+ if (cpuidle_curr_governor->get_poll_time)
+ return cpuidle_curr_governor->get_poll_time(drv, dev);
+
+ return cpuidle_default_poll_time(drv, dev);
+}
+
+/**
* cpuidle_install_idle_handler - installs the cpuidle idle loop handler
*/
void cpuidle_install_idle_handler(void)
Index: linux-2.6.git/drivers/cpuidle/poll_state.c
===================================================================
--- linux-2.6.git.orig/drivers/cpuidle/poll_state.c 2019-06-13 17:57:33.111185824 -0400
+++ linux-2.6.git/drivers/cpuidle/poll_state.c 2019-06-13 18:01:19.846944820 -0400
@@ -20,16 +20,9 @@
local_irq_enable();
if (!current_set_polling_and_test()) {
unsigned int loop_count = 0;
- u64 limit = TICK_NSEC;
- int i;
+ u64 limit;

- for (i = 1; i < drv->state_count; i++) {
- if (drv->states[i].disabled || dev->states_usage[i].disable)
- continue;
-
- limit = (u64)drv->states[i].target_residency * NSEC_PER_USEC;
- break;
- }
+ limit = cpuidle_get_poll_time(drv, dev);

while (!need_resched()) {
cpu_relax();
Index: linux-2.6.git/include/linux/cpuidle.h
===================================================================
--- linux-2.6.git.orig/include/linux/cpuidle.h 2019-06-13 17:57:33.111185824 -0400
+++ linux-2.6.git/include/linux/cpuidle.h 2019-06-13 18:01:19.846944820 -0400
@@ -132,6 +132,8 @@
extern int cpuidle_enter(struct cpuidle_driver *drv,
struct cpuidle_device *dev, int index);
extern void cpuidle_reflect(struct cpuidle_device *dev, int index);
+extern u64 cpuidle_get_poll_time(struct cpuidle_driver *drv,
+ struct cpuidle_device *dev);

extern int cpuidle_register_driver(struct cpuidle_driver *drv);
extern struct cpuidle_driver *cpuidle_get_driver(void);
@@ -166,6 +168,9 @@
struct cpuidle_device *dev, int index)
{return -ENODEV; }
static inline void cpuidle_reflect(struct cpuidle_device *dev, int index) { }
+extern u64 cpuidle_get_poll_time(struct cpuidle_driver *drv,
+ struct cpuidle_device *dev)
+{return 0; }
static inline int cpuidle_register_driver(struct cpuidle_driver *drv)
{return -ENODEV; }
static inline struct cpuidle_driver *cpuidle_get_driver(void) {return NULL; }
@@ -246,6 +251,9 @@
struct cpuidle_device *dev,
bool *stop_tick);
void (*reflect) (struct cpuidle_device *dev, int index);
+
+ u64 (*get_poll_time) (struct cpuidle_driver *drv,
+ struct cpuidle_device *dev);
};

#ifdef CONFIG_CPU_IDLE