What is the difference between critical section and mutex?

What is the difference between critical section and mutex?

From a theoretical perspective, a critical section is a piece of code that must not be run by multiple threads at once because the code accesses shared resources. A mutex is an algorithm (and sometimes the name of a data structure) that is used to protect critical sections.

What is boost mutex?

A mutex object facilitates protection against data races and allows thread-safe synchronization of data between threads. A thread obtains ownership of a mutex object by calling one of the lock functions and relinquishes ownership by calling the corresponding unlock function.

Why mutex is faster than semaphore?

The thread which has acquired mutex can only release Mutex when it exits from critical section. Semaphore value is changed according to wait () and signal () operations. Mutex values can be modified just as locked or unlocked. They are faster than mutex because any other thread/process can unlock binary semaphore.

Can we use semaphore in ISR?

Importantly, semaphores can also be used to signal from an interrupt service routine (ISR) to a task. Signaling a semaphore is a non-blocking RTOS behavior and thus ISR safe.

How do I lock my mutex?

Use pthread_mutex_lock(3THR) to lock the mutex pointed to by mutex . When pthread_mutex_lock() returns, the mutex is locked and the calling thread is the owner. If the mutex is already locked and owned by another thread, the calling thread blocks until the mutex becomes available.

Which is faster semaphore or mutex?

Binary semaphore have no ownership. There is ownership associated with mutex because only owner can release the lock. They are faster than mutex because any other thread/process can unlock binary semaphore.

Can mutex be interrupted?

Mutexes are a perfectly reasonable synchronization primitive to use in interrupts. Of course, you do need to ensure that a thread that holds the mutex can’t be interrupted and run a handler that tries to acquire that same mutex!

How can I tell if boost thread is running?

7 Answers. Since you can join a thread even after it has terminated, joinable() will still return true until you call join() or detach(). If you want to know if a thread is still running, you should be able to call timed_join with a wait time of 0.

What is the difference between mutex and critical_section?

The original answer is below. I made a very simple test and according to my measurements the std::mutexis around 50-70x slower than CRITICAL_SECTION. std::mutex: 18140574us CRITICAL_SECTION: 296874us Edit: After some more tests it turned out it depends on number of threads (congestion) and number of CPU cores.

Is the overhead of mutex negligible for 99% of applications?

That’s true, this test tries to measure the overheadof the std::mutex, it’s not trying to prove that the difference is negligible for 99% of applications. Update 10/27/2017 (2): Seems like the situation has changed in favor for std::mutexsince Visual Studio 2015 (VC140).

Is mutexis an STL class?

Pedantry: std::mutexis not an STLclass. Neither is any other synchronization object. – Robᵩ Apr 3 ’12 at 16:29 2 @uray: no, it is a part of the C++11 standard library. STL is a sort of ambiguous term, but it is usually taken to refer to the collections, algorithms , functors and iteratorsin the standard library.

Is mutexis slower on a MacBook Pro?

Edit: After some more tests it turned out it depends on number of threads (congestion) and number of CPU cores. Generally, the std::mutexis slower, but how much, it depends on use. Following are updated test results (tested on MacBook Pro with Core i5-4258U, Windows 10, Bootcamp):