Windows does it right. On the task manager graph, disk cache is not counted as used memory. And for experts, there's a separate "memory composition" diagram, with the following parts: in use, modified, standby, and free.
Linux folks say that unused memory is not good, of course it is. Windows folks say that free memory is a good thing, and of course it is.
See? It actually is the same thing that being seen from different perspective.
30 or so years ago, while watching over a friend of mine's shoulder who was sitting at the gorgeous 3278-2 system console with the legendary beam-spring keyboard, looking into usage stats on an IBM 4381 mainframe, I noticed the CPU (I think it was only one on that machine, that occupied most of a floor) was pegged at 100% usage. When I asked if that was bad, he simply responded:
"Of course it's 100% used! We paid for it, we'd better use it!"
Later I understood that he'd probably be more concerned if the IO processors started to get saturated, but, by then, I was no longer using mainframes.
Absolutely, but these perspectives aren’t equally useful, it depends on the user and their use case.
The real low-level thing reported by Linux is a useful perspective for kernel developers, and maybe for students learning about virtual memory management in operating systems.
However, the fake data reported by Windows task manager is the useful perspective for everyone else. I think 99% of people using these tools are in this category.
So a new user clicking System Monitor will get a RAM graph they understand.
Not it's a human bug (not knowing enough about your system).
>disk cache is not counted as used memory.
But it is, and people would be shocked to see that windows uses 17GB of memory after startup ;)
I know enough about my systems, yet I think Windows is doing it right. The numbers reported by Linux, or visible on the “memory composition” diagram in Windows task manager, are borderline useless for everyone except OS kernel developers.
Despite I know these hairy implementation details about the ways OS kernel manages physical memory, I don’t really care. When I check these system tools, in 100% of cases I want answer to the question “how much ram my applications could use without swapping”.
>Despite I know these hairy implementation details about the ways OS kernel manages physical memory, I don’t really care.
I do, and obviously everyone that implements top and htop etc.