the bad performance of kde i wrote about in the previous thread seems to be related to ram use

kde is freezing and often takes 100 cpu on 256 M box
kde starts ok on 512 M box but slows down when i open applications (allthough it does not touch swap !)
kde is ok all the time on 1024 M box

on the 1024 M box cpu speed does not matter much
switching composite effects on / off dont matter much

most of the memory use seen in sysguard is cache

in kde 3 the size of both application memory and cache is less than kde 4

what does kde 4 take more memory for ? (in apps / cache)

can the contents of the cache be measured for each application alone ? (to find the bad app)

are there systm wide settings that can lower memory use in kde / qt widgets / plasma etc ?

The cache is managed by the Kernel. It is likely that KDE 4 simply accesses many more files, probably icons or the Plasma theme.

changing the plasma theme from oxygen to naked and logging in out does not make much difference

icons wont take more cache than they did in kde 3 right ?

what else to try ?

edit
does cache contain only stuf from the hd ?

if yes then what are the references to 'gradients cache' in the source code of polyester qt theme ? where it appears in sysguard ?

The gradients cache would either be normal memory usage by Qt applications, or in X. KDE 4 ships with higher resolution images for icons, which will take more disk space.

For all intents and purposes, cache is free memory the kernel is using to speed up disk IO. A correctly configured system will have less than 10mb of RAM free and huge amounts used in disk caches and buffers.

Sysguard is only aware of the kernel level disk cache, and buffers. It is common for applications to allocate memory to store pre-sorted / parsed / processed data for later use.

how cn i see the filenames in the cache ? (i'd like access times too)

While there is probably utilities to do that, they will likely require being run as root, and I do not know what they would be called.

what are other ways to see

whats in the cache (ie what files does kde access - maybe without justification)

what do apps use more memory for (than their kde 3 versions)

the problems are with strigi and akonadi being disabled

is Akondi safe to install? Or is it still in beta? (I'm not even entirely sure what it does, the only things I can find about it is that KDE 4 includes it)

Akonadi is a Personal Information Management (PIM) storage system. Currently it handles only addressbooks and calendars (including Google Calendar with an optional add-on), but for KDE 4.4 there will be a full switch of the whole KDEPIM infrastcuture. Also Akgregator is being ported to Akonadi.

i remove it after kde install (with the option to ignore package dependencies) cause it makes the desktop open slower

it did not crash on me and kde did not have issues running without it

Note that removing Akonadi may cause some PIM applications to become unusable, with this effect increasing soon since Akregator and KMail are being ported.

i find that when i run akonadi server, ~40% of available CPU cycles are being used by the DBus daemon, and ~ 20% by a process called akonadi_nepomuk--constantly. having only one slow CPU, that isn't something i can afford, so i keep akonadi server stopped, which solves the problem. this way i am not able to use akonadi resources, of course.

is this common behavior for akonadi, or did i mess up things in my configuration somewhere? (akonadi starts without errors.)

thanks for letting me know,
phani.

Having not played with Akondi yet, is this slowdown confirmed? I'd rather my machine went as fast as it is...

I have Nepomuk disabled.... however Akonadi likes memory far too much for my liking.

i now compare 3 boxes running kde 4

my mulimedia box (sinnoh)
pentium 4 3.0 GHZ HT
onboard SIS 661fx graphics 16 M
256 M ram KDE 4.0 - 4.2 - freezing slow
1024 M KDE 4.2 - 4.2.85 - fast
standard memory use - 200 M application memory + 500 M cache + the rest unused
direct rendering is not working on this card
looks like this box only needed more ram

on of my desktops (viridian)
celeron 4 2.6 GHZ with dual channel ram
onboard intel 865G graphics 32 M
256 M ram KDE 4.1 - freezing slow
512 M ram KDE 4.1 - 4.2.85 - slow but near usable
1024 M ram KDE 4.2 - 4.2.85 - usable but with display lags no matter what is open and whether desktop efects are enabled
1536 M ram - no difference from 1024 M
direct rendering is working and desktop effects are functional (similar performance with opengl and xrender). disabling effects does not make box faster
desktop effects sometimes kick off with 512 M. does not happen with 1024

my notebook (kite)
celeron M 1.4 GHZ
onboard intel 915 graphics 32 M
256 M ram KDE 4.2 - quite fast if no apps are open otherwise near unusable slow
desktop effects work amazingly fast and well
disabling effects / switching to vesa driver does not improve performance
(i am going to upgrade memory here soon)

all the computers run faster with kde 3.5 (except sinnoh after i installed 1024 M in it)

i can measure exact memory use (with kde 3.5 too) and upload ksysgard snapshots