Linux process management
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The document discusses Linux process management and the life cycle of a process. It explains that a process is an instance of execution that uses system resources to complete its task. The life cycle includes process creation through a fork system call, copying of the program code through exec, termination with exit, and removal after the parent process is notified via wait. It also defines a thread as a parallel execution unit within a single process that can share resources.
Linux process management
- 1. Understanding the Linux operating system
- 2. PERFORMANCE TUNING Performance tuning is a challenging task that requires in-depth understanding of the hardware, operating system, and application.
- 3. LINUX PROCESS MANAGEMENT Process management is one of the most important roles of any operating system. Linux process management implementation is similar to UNIX® implementation. It includes process scheduling, interrupt handling, signaling, process prioritization, process switching, process state, process memory, and so on.
- 4. WHAT IS A PROCESS A process is an instance of execution that runs on a processor. The process uses any resources that the Linux kernel can handle to complete its task.
- 5. LIFE CYCLE OF A PROCESS Every process has its own life cycle such as creation, execution, termination, and removal. These phases will be repeated literally millions of times as long as the system is up and running. Therefore, the process life cycle is very important from the performance perspective.
- 6. LIFE CYCLE OF A PROCESS When a process creates a new process, the creating process (parent process) issues a fork() system call. When a fork() system call is issued, it gets a process descriptor for the newly created process (child process) and sets a new process id. It copies the values of the parent process’ process descriptor to the child’s. At this time the entire address space of the parent process is not copied; both processes share the same address space.
- 7. LIFE CYCLE OF A PROCESS The exec() system call copies the new program to the address space of the child process. Because both processes share the same address space, writing new program data causes a page fault exception. At this point, the kernel assigns the new physical page to the child process.
- 8. LIFE CYCLE OF A PROCESS When program execution has completed, the child process terminates with an exit() system call. The exit() system call releases most of the data structure of the process and notifies the parent process of the termination sending a signal
- 9. LIFE CYCLE OF A PROCESS The child process will not be completely removed until the parent process knows of the termination of its child process by the wait() system call. As soon as the parent process is notified of the child process termination, it removes all the data structure of the child process and release the process descriptor.
- 10. THREAD A thread is an execution unit generated in a single process. It runs parallel with other threads in the same process. They can share the same resources such as memory, address space, open files, and so on. They can access the same set of application data. A thread is also called Light Weight Process (LWP). Because they share resources, each thread should not change their shared resources at the same time. The implementation of mutual exclusion, locking, serialization, and so on, are the user application’s responsibility