Memory Management

Linux Tutorials - Herong's Tutorial Examples

∟Memory Management

This chapter provides introductions and tutorial notes on memory management. Topics include memory layers and access speed; cache memory levels; virtual memory and physical memory mapping; page table; buffers, caches and swap spaces; memory usage reporting tools: free, ps, smem, pmap, /proc/meminfo, /proc/{id}/maps, and /proc/{id}/smaps.

Layers of Memory and Access Speed

List CPU Caches and Their Sizes

Virtual Memory vs. Physical Memory

Buffer Memory and Cache Memory

Verify Cache Memory with "cp" Command

What Is Swap Space

Virtual Memory Mapping and Page Table

"ps -o rss,drs,trs,vsz,sz" - Process Status Options

smem - Process Memory Usage Report

pmap - Process Memory Map

/proc/{id}/maps - Process Memory Map

/proc/{id}/smaps - Process Memory Map Details

Takeaways:

Virtual memory is a logical structure mapped to physical memory dynamically.
Swap space is a reserved area on hard disk to extend RAM to form a larger physical memory.
"free" command prints a summary of physical memory usage.
"/proc/meminfo" pseudo file contains detailed information on physical memory usage.
Virtual memory is divided into pages and mapped to the physical memory through a page table.
"ps -o rss,drs,trs,vsz,sz" command lists all process with their memory usages.
"smem" tool lists all process with their memory usages.
"pmap {pid}" command prints memory map for a given process.
"/proc/{pid}/maps" pseudo file contains memory map for each process.
"/proc/{pid}/smaps" pseudo file contains memory map for each process with details.