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Posts Tagged ‘xfce’

KDE vs XFCE in terms of memory usage

For the moment I have to cope with a low-memory machine at home, so I decided to switch it from KDE to XFCE. But is it really worth it, in terms of memory savings? I decided to measure…

First of all, I’m not trying to do rigorous analysis here but just do some estimates to make a decision for personal use. Still, if you find something in my method which invalidates the results I obtained, I’d be glad to know about it.

To know the memory consumption of each desktop system, I simply started a fresh session in that desktop, opened a terminal and obtained a process listing with ps -e. No other program was opened at the time. Because I did this using a new user account, the test was made with the default configuration and default loaded programs of each desktop system.

Since the important figure in the ps output is the RSS (resident set size) column, I also turned off the swap partition in my computer. The ps manpage says that the RSS field doesn’t count swapped memory from the process. Good thing I noticed this before it was too late!

Here is the result for KDE:

program vsz rss
Xorg 23,936 18,304
kded 35,608 16,136
kdesktop 33,452 15,200
konsole 33,512 14,540
kicker 34,888 14,388
korgac 33,520 12,788
kwin 30,520 11,628
kpowersave 30,792 11,024
knotify 36,400 10,688
klipper 28,456 9,652
ksmserver 27,124 8,368
artsd 22,452 8,168
kaccess 27,212 8,028
seahorse-agent 20,828 6,608
klauncher 27,476 6,324
kio_file 26,048 5,376
gconfd-2 6,692 3,736
bash 6,368 3,728
kdeinit 25,764 3,516
dcopserver 25,616 2,916
startkde 4,300 1,492
gam_server 3,108 1,408
ssh-agent 4,508 724
dbus-daemon 2,760 532
kwrapper ksmserver 1,692 364
dbus-launch 2,916 340
total 555,948 195,976

And here is the result for XFCE:

program vsz rss
Xorg 27,776 20,788
gnome-terminal 43,652 16,860
xfdesktop 57,172 14,848
update-notifier 24,996 14,480
xfce4-panel 20,580 12,340
notification-daemon 19,156 10,224
xfce4-session 18,016 10,092
xfwm4 16,216 8,344
xfce4-menu-plugin 15,780 7,856
seahorse-agent 20,864 6,772
xfce-mcs-manage 18,812 6,148
gnome-volume-manager 18,108 4,744
Thunar 13,880 4,472
gconfd-2 6,692 3,776
bash 6,412 3,740
bonobo-activation-server 15,264 2,892
xscreensaver 4,240 1,936
/bin/sh /etc/xdg/xfce4/xinitrc — /etc/X11/xinit/xserverrc 4,292 1,444
gam_server 3,108 1,408
dbus-daemon 2,760 892
gnome-pty-helper 2,720 756
ssh-agent 4,508 728
dbus-launch 2,916 440
total 367,920 155,980

So, XFCE uses 152MB of RAM, versus the 191MB KDE uses. Not bad, almost 40MB (20%) less!

That’s not the whole story, though. I also wrote down the output of the free command as a sanity check.

Using KDE:

  total used free shared buffers cached
Mem: 256112 245040 11072 0 20832 138236
-/+ buffers/cache: 85972 170140      
Swap: 0 0 0      

Using XFCE:

  total used free shared buffers cached
Mem: 256112 251340 4772 0 20332 127156
-/+ buffers/cache: 103852 152260      
Swap: 0 0 0      

Look at the “used” column, in the “-/+ buffers/cache” line. That is the actual memory amount being used by the running programs in the computer.

This is a very interesting and surprising result: at the end of the day, XFCE actually uses more memory than KDE! Why, if adding up the resident sizes of the processes from each desktop system you get a different conclusion?

One explanation would be that KDE actually shares more memory between processes than XFCE. Its programs most probably have a greater number of shared libraries in common, which enables the kernel to use the same memory pages for the text section of those libraries accross process images. Unfortunately I didn’t collect data to test that possibility, and it’s late at night now. But it makes sense.

The bottom line, surprisingly enough, is that you should stick with KDE to preserve memory. Or switch to a bare-bones window manager instead of a complete desktop system, like IceWM, Window Maker, Blackbox or something else. But I’m too spoiled by the amenities of a good desktop to do that. 🙂

By the way, the tests were made with KDE 3.5.8 and XFCE 4.4.2 under Debian GNU/Linux unstable (updated on 2008/01/06) on a 32-bit x86 machine.

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