磁盘数据的内存缓存

Question

I've always known that main memory caches data read from files on disk, but I have trouble reconciling this with the typical memory usage of a program, as shown in this diagram:

If I use fread or fgetl on a very large file 2010Stats.txt , on which segment of the above diagram does memory cache data from disk?

Answer 1

That's the address-space of your process. Each process has its own virtual memory address-space. Unless you mmap a file, its data only appears in your process's memory when copied there by a read system call or equivalent. (C stdio / iostream functions will be implemented on top of system calls like that.)

The disk-cache is managed by the OS kernel, which has to keep track of how the physical pages of memory are used, as well the virtual address mappings of every process.