Top view memory is the memory occupied by the current process, excluding the memory occupied by the file system cache
The process in the running queue occupies memory.
Free memory is the remaining physical memory
Who is using the remaining memory? It is occupied by the file system's high-speed cache.
By default, the buffer cache is dynamic because it can be expanded or reduced as needed. To adjust the dynamic buffer cache, you can set the kernel's adjustable parameters nbuf and bufpages to zero, and set dbc_min_pct and dbc_max_pct to the minimum and maximum memory usage ratios respectively. Default Value:
Dbc_max_pct 50
Dbc_min_pct 5
Note: dbc_min_pct cannot be less than 2, and dbc_max_pct cannot be higher than 90.
By setting nbuf or bufpages, you can set the static buffer cache size to a fixed value.
The remaining physical memory viewed by vmstat is the remaining memory page, which must be 4 kb to be equal to the free memory in the top