Linux内核态抢占机制分析

# define sub_preempt_count(val) do { preempt_count() -= (val); } while (0)

#endif

#define inc_preempt_count() add_preempt_count(1)

#define dec_preempt_count() sub_preempt_count(1)

/**

* 在thread_info描述符中选择preempt_count字段

#define preempt_count() (current_thread_info()->preempt_count)

#ifdef CONFIG_PREEMPT

asmlinkage void preempt_schedule(void);

/**

* 使抢占计数加1

#define preempt_disable() \

do { \

inc_preempt_count(); \

barrier(); \

} while (0)

/**

* 使抢占计数减1

#define preempt_enable_no_resched() \

do { \

barrier(); \

dec_preempt_count(); \

} while (0)

#define preempt_check_resched() \

do { \

if (unlikely(test_thread_flag(TIF_NEED_RESCHED))) \

preempt_schedule(); \

} while (0)

/**

* 使抢占计数减1，并在thread_info描述符的TIF_NEED_RESCHED标记被置为1的情况下，调用preempt_schedule()

#define preempt_enable() \

do { \

preempt_enable_no_resched(); \

preempt_check_resched(); \

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