Very Computer

Quote:> While running only linux and a single bash shell it looks like this:

> Mem:  31224K av, 23656K used, 7568K free, 3748K shrd, 6200K buff

> What does the 'used' mean?  Why would such a large % of available
> memory be used with little to nothing running?

File caching and the like.  I have 128M RAM, and at present I have
only 3156K free, allegedly, even though I'm really only running
XEmacs, X and Netscape (each under 15M), a bunch of <1M processes and
a few a little bigger (GNOME processes ~3M, with 2.5M shared).

If you're interested in specific programs, then look at their usage,
not usage over the whole system.  A properly written OS will use as
much memory as you've got, if only to cache files and things.
(Obviously, the OS ought to gracefully release such cached memory on
request, too.)

CMC> While running only linux and a single bash shell it looks like this:
CMC>
CMC> Mem:  31224K av, 23656K used, 7568K free, 3748K shrd, 6200K buff
CMC>
CMC> What does the 'used' mean?

'used' = 'av' - 'free'

It's the sum of memory used by running programs, shared libraries,
kernel buffers, and cache, less the amount of data in swap.

CMC> Why would such a large % of available memory be used with little
CMC> to nothing running?

Of the 23656K used, 9948K is used for things that aren't just program
data.  There's also the "cached" number on the next line which should
be subtracted out.

CMC> What other techniques are there to monitor memory, and how to
CMC> make memory use most efficient?

The 'free' command will give you an instant snapshot of memory use.

In general, the kernel aims to minimize the amount of "free" memory.
In particular, it can allocate "free" memory as cache, which helps
speed up disk accesses and can be thrown away almost without cost if
more physical memory is needed.  So you shouldn't be worried that you
have no "free" memory.

--

"Hey, Doug, do you mind if I push the Emergency Booth Self-Destruct Button?"
"Oh, sure, Dave, whatever...you _do_ know what that does, right?"