Re: Question about free/used memory on Linux

["Pádraig Brady" <P@draigBrady.com>]

Ravinandan Arakali (rarakali) wrote:
> Hi kernel gurus,
> I am trying to find out the memory that's used on my linux box.
> I find that there are quite a few confusing metrics. How do
> I find out the "true" used memory ?
> 
> 1. For eg. "free -m" shows free memory (excluding buffers/caches) 
> as 308 MB while I can see(from "df" output) that the the tmpfs 
> partitions take up about 400 MB. So, does "free -m" not consider 
> the tmpfs partitions ?
> 
> 2. I try to add up RSS field of all processes reported by
> "ps aux" command. But is it true that this would be misleading
> in that, shared memory used by, say 2 processes would show
> up twice here although there's only one copy in memory. Also
> does this consider the fact that there's only one copy
> of shared libraries ?

Have a look at this script so show RAM used by programs:
http://www.pixelbeat.org/scripts/ps_mem.py

Note to display totals you will need this patch applied:
http://lkml.org/lkml/2007/8/13/1224

Pádraig.