Data Storage - Page (memory page|virtual page|chunk)
1 - About
This means that memory address 123 might be directed to physical address 82043 at one time, and physical address 20468 another time. As it turns out, the overhead of individually tracking the virtual to physical translations for billions of bytes of memory would be too great.
Each pages (chunk) can have different states such as:
- “in memory”,
- or “on disk”.
In Linux, those chunks are typically 4Kb.
2 - Articles Related
3 - Shared
Shared page are shared between process. How many processes share is not known.
4 - How to
4.1 - sum it up ?
A memory page can be both in memory and on disk, and if you sum up everything in memory and everything on disk you will count the page twice. Shared pages are even more complicated, as only the fact that they are shared is known. How many processes share is not known. If you sum up all the processes memory that is “in RAM” you will count the shared pages multiple times.