Detailed explanation of the file containing the Linux kernel source code

Explore the detailed explanation of the file where the Linux kernel source code is located

Linux is an open source operating system, and its kernel source code is a core part of its design and functionality and has been widely studied. and use. The Linux kernel source code contains many files, each file is responsible for different functional modules. In this article, we will delve into the role of several key files and specific code examples in the Linux kernel source code to help readers better understand the design and operation of the Linux kernel.

1. kernel/sched/core.c - This file implements the scheduler in the Linux kernel. The scheduler is responsible for deciding which process to execute when to implement functions such as time slice rotation and priority scheduling. Here is a simple code example:

#include <linux/sched.h>
#include <linux/sched/signal.h>

void schedule(void)
{
    struct task_struct *prev, *next;

    prev = current;
    
    next = pick_next_task(); // 选择下一个要运行的进程

    switch_to(next); // 切换到下一个进程执行
}

2. kernel/slab.c - This file implements the Slab allocator in the Linux kernel. The slab allocator is used to efficiently allocate and reclaim memory to improve system performance. Here is a simple code example:

#include <linux/slab.h>

void *kmalloc(size_t size, gfp_t flags)
{
    struct kmem_cache *cache;
    void *ptr;

    cache = get_cache_for_size(size); // 根据分配大小获取合适的缓存
    ptr = alloc_slab(cache); // 从缓存中分配内存

    return ptr;
}

3. kernel/fs/namei.c - This file implements path parsing and file system operations in the Linux kernel. Path parsing is used to convert the file path passed in the user mode into an inode in the kernel for file operations. The following is a simple code example:

#include <linux/fs.h>
#include <linux/path.h>

int vfs_open(const char *pathname, int flags, int mode)
{
    struct path path;
    struct file *file;
    
    int err = kern_path(pathname, LOOKUP_FOLLOW, &path);

    if (!err)
    {
        file = filp_open(&path, flags, mode);
        if (IS_ERR(file))
        {
            err = PTR_ERR(file);
        }
    }
    
    return err;
}

By analyzing the code examples of the above key files, readers can have a deeper understanding of the structure and function of the Linux kernel source code. In addition to these files, the Linux kernel also contains many other important files, covering the implementation of process management, memory management, file systems, etc. Further research and exploration of the Linux kernel source code will help understand the design principles and internal working mechanisms of the operating system, and improve the ability and level of system programming.

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