how much memory does linux use by itself?

[Stuh505]

im wondering how I can get the most juice out of my computer

I've got 512 MB of ram and just having a couple iexplorer windows open I've only got 78 MB of that free...so all that ram is just being used by XP and the few programs which run automatically when I boot up (limewire, kodak digital camera detection, realplayer, norton)

Im trying to analyze other systems and see if they are more efficient. How much memory could I expect the linux OS to use by itself just after booting up, practically?

I am not very familiar with linux but I did work on some redhat machines in the computer lab and was surprised that they seemed to have extremely slow response times just navigating through the task bar, so that kind of disssuaded me to the idea that linux would be this wonderfully clean and efficient system...but tell me the reality of it

 

[piller1999]

I'm using 103 megs of my 1 gig of ram as I respond to this post.

IMHO, Linux is wonderfully efficient with memory.

 

[Stuh505]

Do you mean that you have 921 MB of ram free, or that you have only attribted 103 MB of the ram that is being used to your OS?

 

[piller1999]

I meant that I had 103 megs of ram in use by Linux at the time . The other 921 megs were free.

Applications I was using:
Firefox
Gkrellm ( kind of like a system monitor)

I would also imagine that the GUI has a role to play in the use of ram. I'm using XFCE4, which is a 'light' (as in not as resource hungry) window manager in comparison to KDE or Gnome.

 

[pr0zac]

Linux is much much less resource hungry than Windows. How much it will take up is really variable on what you run though. Like what said above, if you use light GUIs like XFCE or Fluxbox, as opposed to things like GNOME or KDE, you get a really nice cut in resource usage.

-zac

 

[nonsequitur]

while a non-specific answer, 512 mb won't be a problem.

 

[Mandane]

I've used Linux with Gnome... at 128 Megs....

Even though it wasn't ultra fast, it was not that bad. I've tried that with WinXP... and it doesn't do so well.

 

[PadanFain]

Uh

I find KDE and XP to be about the same on default (no secondary apps)

 

[HHunt]

Just booted, with only kdm (the graphical login manager), it looks like this:

last pid:   660;  load averages:  0.00,  0.01,  0.02    up 0+00:11:50  16:40:01
28 processes:  2 running, 26 sleeping
CPU states:  0.0% user,  0.0% nice,  0.0% system,  0.1% interrupt, 99.8% idle
Mem: 33M Active, 27M Inact, 35M Wired, 168K Cache, 27M Buf, 901M Free
Swap: 554M Total, 554M Free

After starting KDE, xmms and konqueror (equal to winamp and IE), it jumps to this:

last pid:   785;  load averages:  0.00,  0.00,  0.00    up 0+00:28:10  16:56:21
53 processes:  1 running, 52 sleeping
CPU states:  8.9% user,  0.0% nice,  2.4% system,  0.0% interrupt, 88.7% idle
Mem: 73M Active, 46M Inact, 61M Wired, 796K Cache, 54M Buf, 816M Free
Swap: 554M Total, 554M Free

As for what the numbers mean:
Active is memory actively used by programs.
Wired is memory currently locked form use by kernel systems (drivers and the like)
Inact, Cache and Buf can be grouped together as "assorted buffering".[1]
Free is, well, free.
Make from the numbers what you will. ("Memory use" is a vague thing. )

According to my dmesg:
real memory = 1073479680 (1023 MB)
avail memory = 1040932864 (992 MB)
(The rest, 31M, is reserved for internal use by the kernel, in addition to holding the kernel itself. I imagine this scales down with less RAM.)

[1] More in use here is a good thing, even if it's not technically "free".

 

[j-rock]

Linux will always use 100% of the ram available. It does this because it caches hard disk reads to memory for faster access. Remember, unused memory is wasted memory. You paid for it, use it for something damn it.

 

[Whatsisname]

My SuSE system with gnome, firefox (which eats up a ton of cpu and memory), gaim and xmms uses only about 1/4 of 512 actively, with the rest of it in cache.

 

[unhappy_mage]

Linux will always use 100% of the ram available. It does this because it caches hard disk reads to memory for faster access. Remember, unused memory is wasted memory. You paid for it, use it for something damn it.

A good point - linux will automatically cache disk reads with memory until it gets something better to do with it. My secondary linux box has 100MB of memory used (of 512) and around 400MB of cache which would instantly evaporate if something tried to use it, so it responds to disk reads faster. Good stuff.

I have a linux distro which boots in 16 MB of ram, but it has no graphical interface, so you're probably not interested. damnsmalllinux runs off a CD and can load itself entirely into RAM - it's blazing fast at that point, give it a whirl.

 

[AdamW]

A typical Linux desktop is no less resource hungry than a _well set up_ XP one, these days. With KDE or GNOME an idle desktop will use somewhere around 100-130MB of RAM; an idle XP desktop uses about the same. However, Linux has the advantage of having lighter desktops like Xfce that can reduce this figure. For the original poster, you would probably see an advantage with Linux because it wouldn't run the resource hogs you currently have (the atrocity that is Real for Windows, Limewire and Norton). Limewire you can actually get for Linux and it would eat as much RAM if you ran it, but you wouldn't need anything like Norton on Linux, and Linux's Realplayer is much slimmer (and doesn't run on startup).

However, this seems like a silly reason to go to Linux. I'm not saying you shouldn't, but if all you're concerned about is resources, why not just fix XP? First, ditch Norton, and get AVG ( http://www.grisoft.com/ ) instead. Second, find the option that tells RealPlayer not to run at boot (yes, there really is one, it's well-hidden though) and turn it on. Third, ditch Limewire unless you really need it, or think about disabling its start on boot and running it only when you actually want to download something. That'll do a heck of a lot to cure your resource situation right off the bat. If you really want to go to Linux, pick a better reason.

 

[Fint]

One of my servers is using eight megs of RAM, for the entire OS, SSH service, and a FTP server.

bwindle@campusftp:~$ free -m
             total       used       free     shared    buffers     cached
Mem:           124         78         46          0         42         27
-/+ buffers/cache:          [B]8[/B]        115
Swap:            0          0          0