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List:       kde-devel
Subject:    Re: KDE4 is a memory hog
From:       Thiago Macieira <thiago () kde ! org>
Date:       2009-07-13 21:27:13
Message-ID: 200907132327.30258.thiago () kde ! org
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Andreas Pakulat wrote:
>On 13.07.09 10:26:34, 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.
>
>Sorry to say that but those numbers don't help at all. All you're seeing
>there is that $someapp uses a certain amount of memory. Where that
>memory is used and wether it could possibly be reduced needs a bit more
>work, in particular profiling the app(s) in question. So run the worst
>memory hogs with valgrind --tool=massif and post the results on the
>relevant developer lists.

I think the numbers do help. They do prove that we need to profile our apps 
and fix them.

Our stacks are far too large. That's easily visible in many applications. 
Here's an excerpt from /proc/`pidof plasma-desktop`/smaps:

096d8000-168ad000 rw-p 096d8000 00:00 0          [heap]
Size:             214868 kB
Rss:              214576 kB
Pss:              214576 kB

Can anyone tell me why Plasma needed to allocate 209.8 MB of RAM? (binary 
1024 units)

The use of MySQL in Amarok and Akonadi increases the memory usage by 
another 30 MB (just by starting MySQL). The use of the NVidia driver 
consumes another 10 MB *per* *process*: amarok, plasma, ksmserver, kwin 
(unless you're using KDE 4.3).

There are definitely memory leaks in some places. In other places, we need 
profiling to find out why we're wasting so much memory.

However, I also know that we are using more memory for caching things, 
pre-rendered pixmaps for example. We use more memory to make the system 
faster. So I don't expect KDE 4 to reach KDE 3 levels again.

No. I expect KDE 4 to excel in other areas, like battery time. For 
example, right now, Plasma wakes up between 20 and 60 times per second due 
to timers. Killing Plasma makes my laptop's power consumption drop by 1 W 
(extending the battery time from 6 to 7 hours). Keeping desktop effects 
enabled consumes another 1.6 W and this time I have no explanation (no 
application wakes up more often). Konqueror also keeps waking up the disk 
every 2 seconds to save its crash recovery, even when there's no change in 
state.

So I expect KDE 4 to be larger, use more memory, to be faster and consume 
less (or the same) power than KDE 3. And, to boot, be more functional and 
more pleasing to the eye.

-- 
  Thiago Macieira  -  thiago (AT) macieira.info - thiago (AT) kde.org
    PGP/GPG: 0x6EF45358; fingerprint:
    E067 918B B660 DBD1 105C  966C 33F5 F005 6EF4 5358

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