Concurrency in the Linux kernel is achieved by allowing multiple processes to run simultaneously. In order to do this, the kernel must provide a mechanism for synchronizing access to shared data structures.
There are two main ways that the kernel can achieve concurrency:
The Linux kernel uses a mix of both preemptive and cooperative multitasking.
Preemptive multitasking is used for critical tasks that cannot afford to be interrupted, such as handling hardware interrupts. Cooperative multitasking is used for tasks that can afford to be interrupted, such as user-space processes.
The Linux kernel uses a number of different synchronization mechanisms to achieve concurrency, including:
The Linux kernel also provides a number of mechanisms for managing process scheduling, memory management, and other aspects of concurrency.
The Linux kernel provides a number of mechanisms for managing process scheduling.
The kernel scheduler is responsible for scheduling processes to run on the CPU. It uses a number of scheduling algorithms to decide which process should run next.
The most common scheduling algorithm is the round-robin scheduler. This scheduler schedules processes in a First In First Out (FIFO) order.
Other scheduling algorithms include the priority scheduler, which schedules processes based on their priority, and the deadline scheduler, which schedules processes based on their deadline.
The kernel also provides a mechanism for real-time processes. Real-time processes have a higher priority than other processes and are guaranteed to be scheduled in a timely manner.
The Linux kernel provides a number of mechanisms for managing memory.
The kernel uses a number of memory management strategies, including paging and swapping.
Paging is a technique that allows the kernel to map process memory into physical memory. This allows the kernel to use physical memory more efficiently.
Swapping is a technique that allows the kernel to write process memory to disk. This allows the kernel to free up physical memory for other processes.
The kernel also provides a mechanism for shared memory. Shared memory allows processes to share memory between themselves.
The Linux kernel provides a number of mechanisms for inter-process communication (IPC).
IPC allows processes to communicate with each other. The most common form of IPC is message passing.
Message passing allows processes to send messages to each other. The kernel provides a number of message passing mechanisms, including pipes, FIFOs, and sockets.
Pipes and FIFOs allow processes to communicate with each other using a unidirectional data stream. Sockets allow processes to communicate with each other using a bidirectional data stream.
The kernel also provides a mechanism for shared memory. Shared memory allows processes to share memory between themselves.
The Linux kernel provides a number of mechanisms for achieving concurrency. These mechanisms include preemptive multitasking, cooperative multitasking, spinlocks, mutexes, semaphores, and a variety of otherprocess scheduling and memory management strategies.