notification chain and timer interrupt

notification chain


Class:
notifier_block


member:
notifier_call: callback function
 
next: 
single list
notifier_block --> notifier_block --> ... --> notifier_block --> notifier_block 


four flavors


atomic_notifier_head
blocking_notifier_head
raw_notifier_head
srcu_notifier_head


method:
notifier_chain_register
notifier_chain_unregister


run:
notifier_call_chain


instance:
clockevents_chain
type
raw_notifier_head


method
clockevents_register_notifier 
    -- raw_notifier_chain_register 
        -- notifier_chain_register


clockevents_unregister_notifier        (x)
    raw_notifier_chain_unregister
        -- notifier_chain_unregister


run:
clockevents_do_notify
    -- raw_notifier_call_chain
        -- __raw_notifier_call_chain
            -- notifier_call_chain
            


element:
static struct notifier_block tick_notifier = {
.notifier_call = tick_notify,
};


clockevents_chain
tick_notify <--> watch_notify <--> horologe_notify  <--> sun_notify <--> ...


implement:
clockevents_register_device
    <-- setup_APIC_timer
    <-- setup_pit_timer
    <-- hpet_legacy_clockevent_register


instance
cpu_chain
type
raw_notifier_head
method
register_cpu_notifier
unregister_cpu_notifier


cpu_chain
timers_nb <--> amd_cpu_notifier <--> hrtimers_nb <--> 
perf_cpu_notify <--> migration_notifier <--> cpucache_notifier <--> 
slab_notifier <--> hotplug_cfd_notifier <--> cpu_nfb <--> vmstat_notifier
    
    
hardware clock


struct clocksource
clocksource_list 
lguest_clock <-->  clocksource_hpet <-->   
<-->  pit_cs <-->  clocksource_jiffies <-->  kvm_clock <-->   xen_clocksource
<--> clocksource_tsc <--> clocksource_uv <--> clocksource_vmi


clocksource_register
clocksource_unregister


struct clock_event_device
clockevent_devices  
struct clock_event_device <--> struct clock_event_device <--> struct clock_event_device
event_handler


clock
{
    struct clocksource: static
    struct clock_event_device: dynamic
}


struct tick_device {
struct clock_event_device *evtdev;
enum tick_device_mode mode;
};


对于tick设备，event_handler 总是被设置为同一个
void tick_set_periodic_handler(struct clock_event_device *dev, int broadcast)
{
if (!broadcast)
        /* global_clock_event->event_handler = tick_handle_periodic  */
dev->event_handler = tick_handle_periodic;
else
dev->event_handler = tick_handle_periodic_broadcast;
}




time_init
    x86_late_time_init
        hpet_time_init
            hpet_enable
                hpet_clocksource_register
                    clocksource_register(&clocksource_hpet);
                hpet_legacy_clockevent_register
                    clockevents_register_device -- hpet_clockevent
                    global_clock_event = &hpet_clockevent;
            setup_pit_timer    


setup_boot_APIC_clock
    setup_APIC_timer
        clockevents_register_device
        
        
x86 arch initialization 
x86_init




irq0->handler 
= timer_event_interrupt 
= global_clock_event->event_handler(global_clock_event);
= tick_handle_periodic 




add_timer
    mod_timer
        internal_add_timer
        
run_timer_softirq
    __run_timers