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Why Linux has 4 layers of “page tables” and how it works exactly
- Linux uses virtual memory to provide each process with its own private address space larger than the physical RAM available.
- Memory is divided into different segments like text, data, stack, and heap, each with its own characteristics in terms of access permissions and memory management strategies employed by the kernel.
- Linux's memory management involves paging and swapping where paging divides the virtual address space into fixed-size pages, and swapping moves memory chunks between RAM and the disk.
- The page table maps virtual addresses to physical addresses, and each level of the page table provides a further level of indirection to manage virtual address space efficiently and scaleable.
- The Linux kernel plays a central role in managing the system's memory, including memory allocation, page table management, and swapping.
- Proper code design, including careful memory allocation and deallocation, is essential in preventing memory leaks that gradually consume available memory and eventually lead to performance issues or system crashes.
- Several tools are available for analyzing memory usage, such as top, htop, free, and valgrind, to help identify and resolve memory-related problems proactively.
- Buddy allocation, slab allocation, and zone-based allocation are sophisticated algorithms used by the kernel to optimize memory usage, ensuring efficient memory allocation and fragmentation minimization.
- Effective memory management is paramount for the stability and performance of any Linux system, and understanding the interactions between processes, virtual memory, and the kernel is crucial for optimizing resource utilization and troubleshooting memory-related problems.
- Regularly reviewing memory usage and proactively addressing potential issues is key to maintaining a healthy and responsive system.
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