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List:       kde-devel
Subject:    Re: KDE4 is a memory hog
From:       Lubos Lunak <l.lunak () suse ! cz>
Date:       2009-07-23 15:20:27
Message-ID: 200907231720.27872.l.lunak () suse ! cz
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On Monday 13 of July 2009, Christian Weilbach wrote:
> Hi,
>
> As I have blogged before here: http://whilos.blogsite.org/?p=102 I have
> certain problems about KDE4's increased memory requirements and I am not
> alone.
> Forgive me the length of the mail, but I have already tried to convince
> people that this is a serious issue and have failed in the past, so I have
> really tried to get proving information together and am looking forward to
> your help.

 Serious issue ... the rule of the big three will always make performance be 
the last one after correctness and availability, unless the performance is so 
bad that it can count as conflicting with correctness. Good performance is a 
bonus *shrug*. And we haven't really had time for that after KDE4.0.

> Still I have tested with exmap as advised by Lubos. See below. The problem
> is that exmap has not really friendly output options, only a GTK interface.

 Exmap includes also a CLI tool that should give text output.

> The benchmarking:
> You find the screenshots of exmap attached. I have always rebooted between
> tests and new users accounts have been freshly created + initialized by a
> KDE4 session and tested after a reboot. I have tested both with GDM and
> KDM, which gave the funny result that KDE4+GDM on OpenSUSE is less memory
> hungry than with KDM?!!
> I have loaded 2xweb browser processes (konqueror for kde/firefox for gnome
> [which is already a kde friendly choice]) + a terminal window as this
> reflects a minimum actually "usable" session for me.
> You can clearly see that Gnome is much better and KDE4 takes ~310-360 mb
> minimum where Gnome with the hungry Firefox (55mb) takes only 210 mb. Gnome
> runs without compositing though (this is an i945 chip btw).

 Yeah, well, that only adds to the unfairness of the comparison then. 
Compositing can take up quite some memory.

> Compared to Lubos' benchmark from 2006
> (http://ktown.kde.org/~seli/memory/desktop_benchmark.html) this is
> generally a lot worse, but most likely also a bit more realistic for an
> average session. But back then KDE3 has been claimed to be more efficient
> and 128mb were enough for a small session. You cannot talk of that anymore,
> really not.
>
> I can do any further testing as you wish and post the results here.

 The pictures show that KDE4 takes more memory, but that's about it. It shows 
there is (most probably) a problem, but it doesn't show anything more. If you 
want to increase the chance something gets done about it, you can continue 
benchmarking and find out what the problems are. It's certainly better to 
say "there is problem X" than just "there is a problem".

 So, I suggest you continue based on 
http://ktown.kde.org/~seli/memory/analysis.html and find the biggest 
problems. X takes quite some memory, so check xrestop. KNotify seems to take 
way too much for what it does, so maybe there's something relatively easy to 
fix. You very likely don't want KOrgac to run, for how much memory it uses, 
and you might want to disable Nepomuk too. And most people can do without 
KXKB, and possibly PulseAudio too. And maybe there's something noticeable 
where all applications waste memory that could be fixed. Or maybe not, but 
hard to say without checking first.

 I suggest you collect all your findings somewhere at techbase.kde.org, for 
possible later usage, it's a better place than dumping it to a mailing list. 
Also, the old wiki.kde.org had a page with all kinds of performance tips, I 
have a snapshot of it at http://ktown.kde.org/~seli/memory/analysis.html 
taken somewhen before it disappeared, so maybe you can start a new one with 
similar user hints at userbase.kde.org . Heck, start a KDE performance 
project if you want, with so many whiners about KDE's performance one could 
be even so naive to think there would be more people interested in helping. 
Improving performance needs to find problems that can be fixed at a decent 
cost and developers to do that, but first analysing the problems is a lot of 
work too, and it needs to be done first.

-- 
Lubos Lunak
KDE developer
--------------------------------------------------------------
SUSE LINUX, s.r.o.   e-mail: l.lunak@suse.cz , l.lunak@kde.org
Lihovarska 1060/12   tel: +420 284 084 672
190 00 Prague 9      fax: +420 284 028 951
Czech Republic       http://www.suse.cz
 
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