Nasty memory usage

Martin · Posted: Sat Jul 06, 2002 8:28 am Post subject: Nasty memory usage

This has been bugging me for a while - I'm getting some nasty memory usage and can't figure out where it's being eaten up. top reports:

512 av, 453 used, 60 free. 0 swap

Some quick addition of proceses adds up to only 170 used. What gives? Is this normal? Does linux just allocate all the memory like that?

(Please explain to this ex MS whore)

Thanks. :wink:

ElCondor · Posted: Sat Jul 06, 2002 8:41 am Post subject:

linux uses all the memory available, if there are no programs loaded ("used memory") it will be filled up with "buffers" and "cache" where "buffers" is like the usual disk cache and "cache" is keeping program code in the memory of programs you have run before.

depending on the kernel, it may also start to swap while there is still free memory! this has been changed by linus at about 2.4.10 and was heavily discussed (and flamed

). the idea is, that a programm starts to swap out it's code when cpu/disk are idle, and when it comes to the point that another program really needs more memory than currently available, the first loaded program just frees the ram and uses it's already swaped data, which can speed things up quite a lot .. but it's terrible on notebooks with enough memory.

PS: does anyone know whether the gentoo-kernels are using the -ac patches to refrain from swapping?

* ElCondor pasa *
_________________
Here I am the victim of my own choices and I'm just starting!

trythil · Posted: Sat Jul 06, 2002 9:23 am Post subject:

You may want to try using free instead of top...top does a notoriously bad job at reporting memory quantities, mostly because it's too stupid to accurately represent things. In particular, multithreaded programs will make top go nuts (and you as well, if you don't know how to read the output).

Here's an example: