From 95833c83f3b812c78e48db4eaa19f6c74958470b Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 11 Jan 2006 22:44:36 +0100 Subject: [PATCH] x86_64: Add idle notifiers This adds a new notifier chain that is called with IDLE_START when a CPU goes idle and IDLE_END when it goes out of idle. The context can be idle thread or interrupt context. Since we cannot rely on MONITOR/MWAIT existing the idle end check currently has to be done in all interrupt handlers. They were originally inspired by the similar s390 implementation. They have a variety of applications: - They will be needed for CONFIG_NO_IDLE_HZ - They can be used for oprofile to fix up the missing time in idle when performance counters don't tick. - They can be used for better C state management in ACPI - They could be used for microstate accounting. This is just infrastructure so far, no users. Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds --- arch/x86_64/kernel/process.c | 48 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) (limited to 'arch/x86_64/kernel/process.c') diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c index c9df991..669cf0e 100644 --- a/arch/x86_64/kernel/process.c +++ b/arch/x86_64/kernel/process.c @@ -36,6 +36,7 @@ #include #include #include +#include #include #include @@ -50,6 +51,7 @@ #include #include #include +#include asmlinkage extern void ret_from_fork(void); @@ -64,6 +66,50 @@ EXPORT_SYMBOL(boot_option_idle_override); void (*pm_idle)(void); static DEFINE_PER_CPU(unsigned int, cpu_idle_state); +static struct notifier_block *idle_notifier; +static DEFINE_SPINLOCK(idle_notifier_lock); + +void idle_notifier_register(struct notifier_block *n) +{ + unsigned long flags; + spin_lock_irqsave(&idle_notifier_lock, flags); + notifier_chain_register(&idle_notifier, n); + spin_unlock_irqrestore(&idle_notifier_lock, flags); +} +EXPORT_SYMBOL_GPL(idle_notifier_register); + +void idle_notifier_unregister(struct notifier_block *n) +{ + unsigned long flags; + spin_lock_irqsave(&idle_notifier_lock, flags); + notifier_chain_unregister(&idle_notifier, n); + spin_unlock_irqrestore(&idle_notifier_lock, flags); +} +EXPORT_SYMBOL(idle_notifier_unregister); + +enum idle_state { CPU_IDLE, CPU_NOT_IDLE }; +static DEFINE_PER_CPU(enum idle_state, idle_state) = CPU_NOT_IDLE; + +void enter_idle(void) +{ + __get_cpu_var(idle_state) = CPU_IDLE; + notifier_call_chain(&idle_notifier, IDLE_START, NULL); +} + +static void __exit_idle(void) +{ + __get_cpu_var(idle_state) = CPU_NOT_IDLE; + notifier_call_chain(&idle_notifier, IDLE_END, NULL); +} + +/* Called from interrupts to signify idle end */ +void exit_idle(void) +{ + if (current->pid | read_pda(irqcount)) + return; + __exit_idle(); +} + /* * We use this if we don't have any better * idle routine.. @@ -180,7 +226,9 @@ void cpu_idle (void) idle = default_idle; if (cpu_is_offline(smp_processor_id())) play_dead(); + enter_idle(); idle(); + __exit_idle(); } preempt_enable_no_resched(); -- cgit v1.1