linux

    User Space        
┌─────────────────┐   
│ Applications    │ User-level programs run here, user apps & tools	 
│ (User Programs) │ like web browsers, text editors, & media players.
├─────────────────┤ 
│ Libraries       │ Precompiled functions & code that apps use.
├─────────────────┤ 
│ Utilities       │ Command-line user utilities like ls & cat. These
│ (Commands)      │ tools are used for scripting and automation.	      
└─────────────────┘

    Kernel Space     
┌─────────────────┐
│                 │ The heart of the OS. It manages hardware & offers 
│ Kernel          │ services to apps, like time-sharing CPU bandwidth,
│                 │ managing memory, and talking to devices.	  
├─────────────────┤
│ File System     │ This module manages files & directories, reading
│ Management      │ and writing data, and managing metadata (inodes).
├─────────────────┤
│ Process Control │ This module manages processes (running programs).
│ and Scheduling  │ It ensures fair CPU sharing, based on nice-ing.  
├─────────────────┤
│ Memory Mgmt     │ This module keeps process data isolated & current.
├─────────────────┤
│ Device Drivers  │ Drivers operate devices, usually in standard ways.
├─────────────────┤
│ Networking      │ Manages network communication. Includes protocols 
│ Stack           │ for data transmission, handling sockets, managing 
│                 │ connections, and routing data.		      
├─────────────────┤ 						      
│                 │ The interface between user space and kernel space.
│ System Calls    │ Allows user programs to access kernel services,   
│                 │ like file operations or memory allocation.	      
├─────────────────┤ 						      
│ Security        │ Security mechanisms include access control,       
│ Mechanisms      │ authentication, and authorization features that   
│                 │ protect the system's resources and data.          
├─────────────────┤ 						      
│ Interrupt       │ The interrupt handler catches hardware interrupts 
│ Handling        │ generated by devices. It manages their arrival    
│                 │ prioritization, & handling.			      
├─────────────────┤ 						      
│                 │ Handles strategies to optimize power usage,       
│ Power Mgmt      │ including sleep states, CPU frequency scaling,    
│                 │ and device power management.		      
└─────────────────┘ 						      

     File System Management
┌──────────────────────────────┐
│ File System                  │ Organizes and manages files and directories
│                              │ on storage devices, providing a structured
│                              │ way to store, retrieve, and organize data.
├──────────────────────────────┤
│ Directory Structure          │ Represents the hierarchy of directories and
│                              │ subdirectories, enabling efficient navigation
│                              │ and organization of files.
├──────────────────────────────┤
│ File Operations              │ Encompasses operations such as opening,
│                              │ reading, writing, closing, & deleting files,
│                              │ ensuring data integrity.
├──────────────────────────────┤
│ Metadata Management          │ Manages metadata associated with files,
│ (Inodes, Permissions, etc.)  │ including information like ownership,
│                              │ permissions, timestamps, and file size.
├──────────────────────────────┤
│ File System Journaling and   │ Maintains a journal or log of changes to the
│ Transactional Support        │ file system to ensure consistency and
│                              │ recoverability in case of failures.
├──────────────────────────────┤
│ Disk Space Allocation        │ Handles the allocation and management of
│                              │ physical storage space on storage devices,
│                              │ preventing fragmentation and optimizing use.
├──────────────────────────────┤
│ Caching and Buffers          │ Implements caching mechanisms to improve
│                              │ file read and write performance, using
│                              │ buffers to temporarily store data.
└──────────────────────────────┘

       Inode Structure
┌───────────────────────────────┐
│          Inode                │ Inodes are essential data structures in
│                               │ Unix-like file systems (such as ext4).
│                               │ They store metadata about files and
│                               │ directories, as well as pointers to the
│                               │ actual data blocks that contain the
│                               │ file's content.
│ ┌───────────────────────────┐ │
│ │      File Metadata        │ │ Inodes store information like file
│ ├───────────────────────────┤ │ permissions, ownership (user and group),
│ │ File Permissions: Owner,  │ │ creation/modification/access timestamps, 
│ │ Group, Timestamps, Size   │ │ and the size of the file.
│ ├───────────────────────────┤ │
│ │ Block Pointers            │ │ Inodes have pointers to data blocks where
│ │ (Direct, Indirect,        │ │ the actual content of the file is stored. 
│ │ Double Indirect, etc.)    │ │ These pointers can be direct (pointing to
│ │                           │ │ data blocks directly), indirect (pointing
│ │                           │ │ to blocks that contain more pointers), 
│ │                           │ │ double indirect (pointing to blocks that
│ │                           │ │ contain indirect pointers), and so on,
│ │                           │ │ enabling efficient storage of large files.
│ ├───────────────────────────┤ │
│ │ Other Metadata            │ │ Inodes can also store extended attributes
│ │ (Extended Attributes,     │ │ (extra metadata not covered by the
│ │ ACLs, etc.)               │ │ traditional attributes) and Access Control
│ │                           │ │ Lists (ACLs) for advanced perms management.
│ └───────────────────────────┘ │
└───────────────────────────────┘
               │
               │
               │
               ▼
     ┌────────────────────┐
     │    Data Blocks     │ The actual content of a file is stored in data
     │   (File Content)   │ blocks. These blocks are pointed to by the block
     │                    │ pointers in the inode. Data blocks can be of
     │                    │ varying sizes and are organized in a way that
     │                    │ optimizes storage efficiency.
     └────────────────────┘

    Process Control
    and Scheduling
┌───────────────────┐
│ Process Control   │
│ and Management    │ Manages processes' creation, termination,
│                   │ synchronization, and communication.
├───────────────────┤
│ Process States    │ Tracks the various states a process can be in,
│                   │ including Running, Ready, Blocked, etc.
├───────────────────┤
│ CPU Scheduling    │ Selects processes for execution, optimizing
│                   │ CPU utilization, response time, and fairness.
├───────────────────┤
│ Context Switching │ Involves saving and restoring the state of
│                   │ processes when switching between them.
├───────────────────┤
│ Inter-Process     │ Facilitates data sharing and communication
│ Communication     │ between processes, using mechanisms like
│                   │ message passing and shared memory.
├───────────────────┤
│ Process Creation  │ Handles the creation of new processes,
│ and Termination   │ including resource allocation and cleanup.
└───────────────────┘

      Process Management
          in Linux
┌───────────────────────────┐
│        User Space         │
│ ┌───────────────────────┐ │
│ │ User Programs         │ │
│ │ (Applications,        │ │
│ │ Utilities, etc.)      │ │
│ └───────────────────────┘ │
│             │             │
│             ▼             │
│ ┌───────────────────────┐ │
│ │ System Calls,         │ │
│ │ Libraries, etc.       │ │
│ └───────────────────────┘ │
│              │            │
│              ▼            │
│ ┌───────────────────────┐ │
│ │     Kernel Space      │ │
│ │ ┌───────────────────┐ │ │
│ │ │ Process Scheduler │ │ │ Manages task exec, optimizes CPU utilization.
│ │ ├───────────────────┤ │ │
│ │ │ Scheduler Queue   │ │ │ Holds tasks awaiting CPU allocation.
│ │ ├───────────────────┤ │ │
│ │ │ Time Management   │ │ │ Ensures fair and efficient task scheduling.
│ │ ├───────────────────┤ │ │
│ │ │ CPU Affinity      │ │ │ Binds process to specific CPUs.
│ │ ├───────────────────┤ │ │
│ │ │ Preemption &      │ │ │ Pauses executing process, switches to another,
│ │ │ Context Switching │ │ │ resumes when needed.
│ │ ├───────────────────┤ │ │
│ │ │ Priority Inversion│ │ │ Prevents low-priority task blocking
│ │ │ Avoidance         │ │ │ high-priority task.
│ │ ├───────────────────┤ │ │
│ │ │ Load Balancing    │ │ │ Distributes tasks for resource optimization.
│ │ ├───────────────────┤ │ │
│ │ │ Real-time Sched   │ │ │ Enforces timing constraints, ensures critical
│ │ │ and Policies      │ │ │ task completion.
│ │ └───────────────────┘ │ │
│ └───────────────────────┘ │
└───────────────────────────┘