rt_mutex的trylock,lock,以及unlock都有fastpath,只用原子变量操作保护并发,并且保证状态转换的前后依赖。 当WAITERS标记位为1时,trylock,lock以及unlock的fastpath都会失效,强迫进入slowpath采用临界区同步。 还有owner已经写上其它task的指针,trylock,lock的fastpath都会失效,强迫进入slowpath采用临界区同步,但不会在fastpat...
int pthread_mutex_trylock(pthread_mutex_t *mutex); 此函数是 pthread_mutex_lock() 函数的非阻塞版本。区别在于如果互斥锁 mutex 已经被上锁,线程不会被阻塞,而是马上返回错误码。 3.6 解锁互斥锁 int pthread_mutex_unlock(pthread_mutex_t *mutex); 调用此函数给 mutex 互斥锁解锁,是对 rt_mutex_re...
futex_lock_pi只有在对rt_mutex进行委托调用(rt_mutex_timed_futex_lock或rt_mutex_trylock)时才会离开临界区,之后又重新回到临界区。虽然pi-futex排队在rt_mutex锁上,但是它的lock和unlock临界区却使用futex模块的共享等待队列的保护锁同步,也就是说,它与跟它共享相同的共享等待队列的futex,都同步地进行futex系统调...
pthread_mutex_init //按指定的属性初始化mutex; pthread_mutex_destroy //删除给定的mutex; pthread_mutex_lock //锁定mutex,如果mutex已被锁定,阻塞当前线程直到解锁; pthread_mutex_trylock //锁定mutex,如果mutex已被锁定,函数立即返回; pthread_mutex_unlock //解锁mutex; 互斥信号类型有PTHREAD_MUTEX_NORMAL (...
快速学习pthread_mutex_init()、pthread_mutex_lock()、pthread_mutex_trylock()、pthread_mutex_unlock()和pthread_mutex_destroy()等同步功能的最好方法是查看。/examples/mutex/mutex.c。特别要提醒的是。/examples/mutex/sema_test.c文件是学习旗语的很好起点。 实时Linux发展方向 实时Linux与Linux一样仍然处于不...
pthread_mutex_init //按指定的属性初始化mutex; pthread_mutex_destroy //删除给定的mutex; pthread_mutex_lock //锁定mutex,如果mutex已被锁定,阻塞当前线程直到解锁; pthread_mutex_trylock //锁定mutex,如果mutex已被锁定,函数立即返回; pthread_mutex_unlock //解锁mutex; ...
pthread_mutex_init //按指定的属性初始化mutex; pthread_mutex_destroy //删除给定的mutex; pthread_mutex_lock //锁定mutex,如果mutex已被锁定,阻塞当前线程直到解锁; pthread_mutex_trylock //锁定mutex,如果mutex已被锁定,函数立即返回; pthread_mutex_unlock //解锁mutex; ...
rt_mutex在PREEMPT_RT用来实现spinlock_t(包括rwlock_t, struct semaphore和struct rw_semaphore) raw_spinlock_t提供spinlock_t原有功能的的特定变种,所以临界区是非抢占的,_irq真的禁用了硬件中断。需要注意的是在raw_spinlock_t上应该使用正常原语(比如spin_lock())。也就是,除了特定架构或者底层调度与同步原语...
rt_mutex_owner() will not return pending owner, it will return NULL when the top waiter is going to take the lock. rt_mutex_next_owner() always return the top waiter. will not return NULL if we have waiters because the top waiter is not dequeued. I have fixed the code that use ...
快速学习pthread_mutex_init()、pthread_mutex_lock()、pthread_mutex_trylock()、pthread_mutex_unlock()和pthread_mutex_destroy()等同步功能的最好方法是查看./examples/mutex/mutex.c。特别要提醒的是./examples/mutex/sema_test.c文件是学习旗语的很好起点。