Kernel Memory Management: Introduction

Kernel Memory Management is a fundamental aspect of operating system design and plays a crucial role in the functioning of the kernel. In general, memory management is responsible for managing the physical memory of a computer system, allocating memory resources to different applications, and freeing up memory resources when they are no longer needed. In the case of the kernel, memory management becomes more complex due to the fact that the kernel itself requires memory resources to function, and must manage memory resources on behalf of other applications. As such, kernel memory management is an important area of study for operating system developers and programmers. 

There are two main aspects to kernel memory management: virtual memory management and physical memory management. Virtual memory management is concerned with the allocation and mapping of virtual memory addresses to physical memory addresses. This allows multiple applications to use the same physical memory resources without interfering with each other. Physical memory management, on the other hand, is concerned with the allocation and deallocation of physical memory pages to the kernel and applications. To better understand kernel memory management, it is important to understand the different types of memory used by the kernel. 

These include:

• Kernel code and data - this is the memory used by the kernel itself to store its own code and data structures.
• User process memory - this is the memory used by applications running in user mode. This includes the stack and heap used by the application.
• Kernel stack - each thread in the kernel has its own stack, used to store temporary data.
• Kernel heap - this is a general-purpose memory allocator used by the kernel to dynamically allocate memory.
• Device memory - this is memory used by devices and peripherals connected to the system.
• Direct Memory Access (DMA) memory - this is memory used by devices to directly access memory without going through the CPU.

Effective kernel memory management involves balancing the needs of the kernel and applications for memory resources, while also ensuring that memory is used efficiently and effectively. This often involves techniques such as memory pooling, garbage collection, and memory mapping.

In subsequent posts, I will be dwelling deeper into each of these subtopics with snippets from kernel code for illustrator purpose. the idea is to simplify memory understanding when it comes to Linux as it can be bit hairy at times.