Re: Linux memory management

[Steven Pritchard <steve@silug.org>]

On Wed, Oct 16, 2002 at 01:58:05PM -0500, Charlie Brune wrote:
> What's up with that?  Does Linux grab memory

Yes.

> and just never give it back. 

No.

> I've got the "free" command logging to a file and the "Mem:" usage NEVER
> goes down.  Is this O/S greedy, or what?!

When possible, yes.  You want the kernel to use all available memory
for caching data to and from disk and such.  As memory pressure
increases, either the caches shrink, or stuff gets swapped.  In many
cases, you want long-running idle processes to get swapped out to free
up memory for caching, so that's why you'll often see a box with a ton
of RAM swapping, even though the RAM used by programs is a very small
percentage.

What's really fun is unpacking a kernel tree and seeing no disk
activity, then doing a kernel build and *still* seeing no disk
activity.  That used to be possible (back in the early 2.2.x days) on
a nice dual Xeon or PIII with a half gig of RAM or so.  I don't know
what it would take now.  (I certainly don't have anything that nice.)

Steve
-- 
steve@silug.org           | Southern Illinois Linux Users Group
(618)398-7360             | See web site for meeting details.
Steven Pritchard          | http://www.silug.org/

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