how to check semaphores in linux

Differences between semaphores and spin locks The spin lock does not cause the caller to sleep.If the spin lock has been maintained by another execution unit, the caller will keep repeating to check whether the lock holder has released the lock.

Source:Inter-process communication for Linux-semaphoresInter-process communication for Linux-semaphores版权声明：本文章内容在非商业使用前提下可无需授权任意转载、发布。转载、发布请务必注明作者和其微博、公众号地址，以便读者询问问题和甄误反馈，共同进步。微博ID：orroz公众号：Linux系统技术ObjectiveSemaphores are also called semaphores,

In the driver, when multiple threads access the same resource at the same time (the global variable in the driver is a typical shared resource), it may lead to a "race State ", therefore, we must control the concurrency of shared resources. The most

Reproduced http://blog.csdn.net/yusiguyuan/article/details/14161225   The synchronization technology between threads mainly focuses on mutex locks and condition variables. The combination of condition variables and mutex can well handle the

From: http://charette.no-ip.com: 81/programming/2010-01-13_posixsemaphores/# Problem The problem with POSIX semaphores Summary It has been a number of years since I 've used named semaphores. it cocould be that the last time I used a named

In multi-threaded or multi-process programming, there is a very important thing to focus on, that is, synchronization and mutual exclusion problems.Synchronization refers to the collaboration between multiple processes, whereas mutual exclusion

Linux inter-process communication (IPC) programming practices (10) System V semaphores --- typical PV operations// P primitive // P (semaphore * S)Wait (semaphore * S ){-- S-> value; if (S-> value {// Set the current process to blocking// Insert the

Processes are mutually exclusive with P and V Operations. I. Critical resources What is a critical resource:At any time, only the resources used by one process are allowed as critical resources. What is a critical section:Access critical

One problem that must be solved in the Linux device driver is the concurrent access by multiple processes to shared resources. concurrent access leads to competing states. Linux provides a variety of solutions to competing states, these methods are

1. Definition: Header file: Data Type: struct semaphore Directly create: Void sema_init (struct semaphore * SEM, int Val);/* where Val is the initial value of the semaphore */ Secondary macro:Declare_mutex (name);/* initialize a semaphore variable