Linux memory usage

• Do a free command, see the used, free memory, as well buffers and cached memory

        

• Do a total of all running procecss memory usage, including init, the kernel is not reported in "ps"

$ ps -eo pid,ppid,rss,vsize,pcpu,pmem,cmd -ww --sort=pid|grep -v RSS|awk '{total=total+$3}END{print total}'

2194756

• How much used for kernel

Total physical RAM - buffers - cached - total running process RAM usage - free:
8175520 - 535184 - 3158588 - 2194756 - 2105836 = 92236KB

Notes:

• Reference: http://mail.nl.linux.org/linux-mm/2003-03/msg00077.html
•  Memory Buffers - A page cache for the virtual memory system. The kernel keeps track of frequently accessed memory and stores the pages here.
• Memory Cached - Any modern operating system will cache files frequently accessed.
• VSIZE (Virtual memory SIZE) - The amount of memory the process is currently using. This includes the amount in RAM (including buffers/cached) and the amount in swap.
• RSS (Resident Set Size) - The portion of a process that exists in physical memory (RAM).
• The kernel - The kernel will consume a couple of MB of memory. The memory that the kernel consumes can not be swapped out to disk. This memory is not reported by commands such as "free" or "ps".