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Mutex comes into the picture when two threads work on the same data at the same time. It acts as a lock and is the most basic synchronization tool. When a thread tries to acquire a mutex, it gains the mutex if it is available, otherwise the thread is set to sleep condition. Mutual exclusion reduces latency and busy-waits using queuing and context switches. Mutex can be enforced at both the hardware and software levels.
Disabling interrupts for the smallest number of instructions is the best way to enforce mutex at the kernel level and prevent the corruption of shared data structures. If multiple processors share the same memory, a flag is set to enable and disable the resource acquisition based on availability. The busy-wait mechanism enforces mutex in the software areas. This is furnished with algorithms such as Dekker's algorithm, the black-white bakery algorithm, Szymanski's algorithm, Peterson's algorithm and Lamport's bakery algorithm.
Mutually exclusive readers and read/write mutex class codes can be defined for an efficient implementation of mutex.