On 2017-03-18 09:28, Otto Moerbeek wrote:
On Fri, Mar 17, 2017 at 01:04:29PM +0200, Mihai Popescu wrote:
Hello,
I am using top to show running programs activity on an OpenBSD system.
Is there another better command to show in detail the memory used by
programs?
My system has 8GB physical RAM. Looking at this, can someone tell me
if OpenBSD uses the "swap memory" model used by other OSes, basically
moving chunks from physical memory to the swap partition when they are
not used?
Pages in physical memory are paged out to swap space, if thery are not
actively used *and* there is general shortage of physical memory. If
physical memory is not tight, no swapping will occur.
If a program ask for a memory allocation, is this request satisfied
imediately if there is enough physical RAM available or is it done at
the moment the program needs to do read/write on that memory?
Virtual memory is allocated subject to per process ulimits and general
platform limitation but not touched on allocation. Only when the
virtual pages are referred to they will become backed by physical
pages. These pages might be paged out to swap if need be.
Expanding the first question, is there a command to show all these
details, like total memory used, static and dynamic, how much is
physical or swap, etc?
top shows two columns: SIZE and RES. SIZE is the total virtual memory
used by a process (executable, stack and data). RES are the total
physical pages in use by a process. Both columns can be deceptive
since e.g. memory can be shared by multiple processes. There are also
things like dynamically loaded libraries that complicate matters.
procmap can show a lot of details about a process, but that's maybe
too much for your purpose. It also is disabled in a default setup.
but:
$ ps -axO tsiz,dsiz,ssiz,vsz,rss,maxrss,%mem,lim
Will show you most of the details you're after. See the man page for
some explanation.
Note: the SIZE and RES columns from top are called vsz and rss in ps,
text is the name fthe executable program code.
Thanks for the explanation!
May I ask why I am getting RES > SIZE sometimes?
Here is one line as example:
5411 d.lowe 2 0 12M 16M sleep/2 kqread 5:32 0.00% tmux
-Otto
