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Subject[PATCH 11/18] cpuidle: stop using pm_idle
Date
From: Len Brown <len.brown@intel.com>

pm_idle does not scale as an idle handler registration mechanism.
Don't use it for cpuidle. Instead, call cpuidle directly, and
allow architectures to use pm_idle as an arch-specific default
if they need it. ie.

cpu_idle()
...
if(cpuidle_call_idle())
pm_idle();

cc: x86@kernel.org
cc: Kevin Hilman <khilman@deeprootsystems.com>
cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Len Brown <len.brown@intel.com>
---
arch/arm/kernel/process.c | 4 +++-
arch/sh/kernel/idle.c | 6 ++++--
arch/x86/kernel/process_32.c | 4 +++-
arch/x86/kernel/process_64.c | 4 +++-
drivers/cpuidle/cpuidle.c | 38 ++++++++++++++++++--------------------
include/linux/cpuidle.h | 2 ++
6 files changed, 33 insertions(+), 25 deletions(-)

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 94bbedb..dc9d685 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -30,6 +30,7 @@
#include <linux/uaccess.h>
#include <linux/random.h>
#include <linux/hw_breakpoint.h>
+#include <linux/cpuidle.h>

#include <asm/cacheflush.h>
#include <asm/leds.h>
@@ -196,7 +197,8 @@ void cpu_idle(void)
cpu_relax();
} else {
stop_critical_timings();
- pm_idle();
+ if (cpuidle_call_idle())
+ pm_idle();
start_critical_timings();
/*
* This will eventually be removed - pm_idle
diff --git a/arch/sh/kernel/idle.c b/arch/sh/kernel/idle.c
index 425d604..9c7099e 100644
--- a/arch/sh/kernel/idle.c
+++ b/arch/sh/kernel/idle.c
@@ -16,12 +16,13 @@
#include <linux/thread_info.h>
#include <linux/irqflags.h>
#include <linux/smp.h>
+#include <linux/cpuidle.h>
#include <asm/pgalloc.h>
#include <asm/system.h>
#include <asm/atomic.h>
#include <asm/smp.h>

-void (*pm_idle)(void) = NULL;
+static void (*pm_idle)(void);

static int hlt_counter;

@@ -100,7 +101,8 @@ void cpu_idle(void)
local_irq_disable();
/* Don't trace irqs off for idle */
stop_critical_timings();
- pm_idle();
+ if (cpuidle_call_idle())
+ pm_idle();
/*
* Sanity check to ensure that pm_idle() returns
* with IRQs enabled
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 8d12878..61fadbe 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -38,6 +38,7 @@
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/kdebug.h>
+#include <linux/cpuidle.h>

#include <asm/pgtable.h>
#include <asm/system.h>
@@ -109,7 +110,8 @@ void cpu_idle(void)
local_irq_disable();
/* Don't trace irqs off for idle */
stop_critical_timings();
- pm_idle();
+ if (cpuidle_idle_call())
+ pm_idle();
start_critical_timings();
}
tick_nohz_restart_sched_tick();
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index bd387e8..210641a 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -37,6 +37,7 @@
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/ftrace.h>
+#include <linux/cpuidle.h>

#include <asm/pgtable.h>
#include <asm/system.h>
@@ -136,7 +137,8 @@ void cpu_idle(void)
enter_idle();
/* Don't trace irqs off for idle */
stop_critical_timings();
- pm_idle();
+ if (cpuidle_idle_call())
+ pm_idle();
start_critical_timings();

/* In many cases the interrupt that ended idle
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 041df0b..d4c5423 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -25,10 +25,10 @@ DEFINE_PER_CPU(struct cpuidle_device *, cpuidle_devices);

DEFINE_MUTEX(cpuidle_lock);
LIST_HEAD(cpuidle_detected_devices);
-static void (*pm_idle_old)(void);

static int enabled_devices;
static int off __read_mostly;
+static int initialized __read_mostly;

int cpuidle_disabled(void)
{
@@ -56,25 +56,23 @@ static int __cpuidle_register_device(struct cpuidle_device *dev);
* cpuidle_idle_call - the main idle loop
*
* NOTE: no locks or semaphores should be used here
+ * return non-zero on failure
*/
-static void cpuidle_idle_call(void)
+int cpuidle_idle_call(void)
{
struct cpuidle_device *dev = __this_cpu_read(cpuidle_devices);
struct cpuidle_state *target_state;
int next_state;

+ if (off)
+ return -ENODEV;
+
+ if (!initialized)
+ return -ENODEV;
+
/* check if the device is ready */
- if (!dev || !dev->enabled) {
- if (pm_idle_old)
- pm_idle_old();
- else
-#if defined(CONFIG_ARCH_HAS_DEFAULT_IDLE)
- default_idle();
-#else
- local_irq_enable();
-#endif
- return;
- }
+ if (!dev || !dev->enabled)
+ return -EBUSY;

#if 0
/* shows regressions, re-enable for 2.6.29 */
@@ -99,7 +97,7 @@ static void cpuidle_idle_call(void)
next_state = cpuidle_curr_governor->select(dev);
if (need_resched()) {
local_irq_enable();
- return;
+ return 0;
}

target_state = &dev->states[next_state];
@@ -124,6 +122,8 @@ static void cpuidle_idle_call(void)
/* give the governor an opportunity to reflect on the outcome */
if (cpuidle_curr_governor->reflect)
cpuidle_curr_governor->reflect(dev);
+
+ return 0;
}

/**
@@ -131,10 +131,10 @@ static void cpuidle_idle_call(void)
*/
void cpuidle_install_idle_handler(void)
{
- if (enabled_devices && (pm_idle != cpuidle_idle_call)) {
+ if (enabled_devices) {
/* Make sure all changes finished before we switch to new idle */
smp_wmb();
- pm_idle = cpuidle_idle_call;
+ initialized = 1;
}
}

@@ -143,8 +143,8 @@ void cpuidle_install_idle_handler(void)
*/
void cpuidle_uninstall_idle_handler(void)
{
- if (enabled_devices && pm_idle_old && (pm_idle != pm_idle_old)) {
- pm_idle = pm_idle_old;
+ if (enabled_devices) {
+ initialized = 0;
cpuidle_kick_cpus();
}
}
@@ -440,8 +440,6 @@ static int __init cpuidle_init(void)
if (cpuidle_disabled())
return -ENODEV;

- pm_idle_old = pm_idle;
-
ret = cpuidle_add_class_sysfs(&cpu_sysdev_class);
if (ret)
return ret;
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index b89f67d..b51629e 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -123,6 +123,7 @@ struct cpuidle_driver {

#ifdef CONFIG_CPU_IDLE
extern void disable_cpuidle(void);
+extern int cpuidle_idle_call(void);

extern int cpuidle_register_driver(struct cpuidle_driver *drv);
struct cpuidle_driver *cpuidle_get_driver(void);
@@ -137,6 +138,7 @@ extern void cpuidle_disable_device(struct cpuidle_device *dev);

#else
static inline void disable_cpuidle(void) { }
+static inline int cpuidle_idle_call(void) { return -ENODEV; }

static inline int cpuidle_register_driver(struct cpuidle_driver *drv)
{return -ENODEV; }
--
1.7.5.rc0


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