The Linux kernel's process scheduling is a key part of the operating system, which determines which process runs when. The Linux kernel uses a multi-level feedback queue scheduling algorithm, which includes the following main components and principles:
Process queue : The Linux kernel maintains multiple process queues, each queue corresponding to a different process priority. Queues usually include real-time queues, time slice queues and I/O waiting queues.
Time Slice : Each process is assigned a time slice, which represents the time it executes on the CPU. When a process has used up its time slice, it is moved to a lower priority queue so that other processes have a chance to execute.
Process status : A process can be in different states, such as running, ready, waiting, etc. The kernel uses state to determine which processes can run.
Preemption : The Linux kernel supports process preemption, which means that high-priority processes can preempt the CPU during the execution of low-priority processes.
Process scheduling strategy : The Linux kernel supports different process scheduling strategies, including completely fair scheduling (CFS), real-time scheduling (RT), and other variants. CFS is Linux's default scheduling policy, which attempts to fairly allocate CPU time to each process.
Load balancing : In a multi-processor system, the Linux kernel will try to keep the load balance of each processor to make full use of system resources.
The basic principles of process scheduling are fairness and efficiency. The goal of the Linux kernel is to allocate CPU time slices as fairly as possible to ensure that each process has a chance to run while using system resources as efficiently as possible. It uses time slices and queues to achieve these goals.
For real-time processes, the Linux kernel provides precise scheduling to ensure that they run as scheduled. This is a critical performance requirement, especially for embedded systems and multimedia applications.