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