[ale] Funny Mem Usage

[Joseph A. Knapka]

Jeff Hubbs wrote:
> 
> I just put RH 7.1 on a machine I'm putting together, more as a test than
> anything else.  It's a K6-2+/500, 512MB RAM.
> 
> Here is what top (M option - sort by memory use) says:
> 
>   1:29am  up  2:33,  5 users,  load average: 1.02, 1.02, 1.00
> 67 processes: 62 sleeping, 4 running, 0 zombie, 1 stopped
> CPU states:  0.3% user,  0.5% system, 99.0% nice,  0.0% idle
> Mem:   504288K av,  211924K used,  292364K free,       0K shrd,   25156K
> buff
> Swap:   56408K av,       0K used,   56408K free                   88904K
> cached
> 
>   PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME COMMAND
> 13219 jeff      20  19 15012  14M   784 R N  99.0  2.9 126:27 setiathome
>   869 root       9  -1 14048  13M  2096 S <   0.1  2.7   0:23 X
>   973 root       9   0 10340  10M  9084 S     0.0  2.0   0:01 kdeinit
>   979 root       9   0  9476 9476  8280 S     0.0  1.8   0:01 kdeinit
> 13165 root       9   0  8340 8340  7448 S     0.0  1.6   0:01 kdeinit
> 13220 root       9   0  8340 8340  7448 S     0.0  1.6   0:00 kdeinit
>   971 root       9   0  7684 7684  6936 S     0.0  1.5   0:00 kdeinit
>   983 root       9   0  7596 7596  6924 S     0.0  1.5   0:00 kdeinit
>   969 root       9   0  6980 6980  5876 S     0.0  1.3   0:00 knotify
>   986 root       9   0  6832 6832  6244 S     0.0  1.3   0:00 kdeinit
>         .
>         .
>         .
> 
> Note that I have KDE and SETI at Home running, and nothing else of note.
> However, look at that "211924K used" business.  Is top misreporting this
> somehow?  Nothing seems to justify nearly half of this RAM being taken
> up, including cache.

OK, you've got 110-odd MB in the cache (buffers and pages), and
another 50 or so in process VM pages, even allowing for the fact
that many of those pages are shared (eg the kdeinit procs are all
sharing the text pages in their working sets). That leaves 60MB or
so unaccounted.

A number of things could be using that memory. Most obviously, if
the rest of the processes on your machine are not sharing much,
they might account for a lot of that in a nickel-and-dime fashion.
If you've got some strange hardware driver that uses a lot of
memory, or some strange hardware driver that leaks memory (:(),
that could be it. Also, if your machine handles a lot of net traffic
(eg is a router/firewall), then the IP stack might be sucking down
a chunk-o-RAM. Pages allocated by the kernel for internal use
(including the kernel text pages themselves) are not accounted
in /proc/meminfo, which (I'm pretty sure) is where top gets
its memory data.

-- Joe
 
-- Joe Knapka
"You know how many remote castles there are along the gorges? You
 can't MOVE for remote castles!" -- Lu Tze re. Uberwald
// Linux MM Documentation in progress:
// http://home.earthlink.net/~jknapka/linux-mm/vmoutline.html
* Evolution is an "unproven theory" in the same sense that gravity is. *
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