Which graphics driver do you use? It is probable that the driver in use is leaking memory.

Yep, it probably related to nvidia driver, but not to a driver version in particular, but nvidia drivers in general.

I said in the second line of my post

"My system is kde 4.4.5 , 2.6.32.26-175.fc12.x86_64 with nvidia driver 195.36.31 (9300GS)"

matrs - it is an older Nvidia driver, current stable is the 260 series consider up'ing

same for Kde - current is 4.6.1

things get fixed, leaks get patched - stability is good but after awhile your running with issues that have been resolved and without functionality that has been added

Yep, i know is an older system, i'm in fedora 12 because i'm producing some important stuff, after that i'll upgrade. But,as mentioned by ChoK in the first page, with my same video card and upgraded nvidia drivers and kde , still there are memory problems. That's no strange, because with every kde and nvidia drivers version since two years ago i've had the same problem, and probably other nvidia users too. I can afford it 'cause i have a 4gb ram notebook.

But yes, it's true, better I wait get an upgraded software and then í'll post results.

matrs - if stability is what's critical why would you use something as bleeding edge as Fedora, what about Red Hat or it's offspring like CentOS or Scientific ?

The truth is that is my first time using the same fedora system so long, usually I use it for maximum 10-12 months, and in that period of time fedora keeps upgraded version for almost every important software that I use (like kde and nvidia drivers). In general, it works very good for me. I tested scientific linux two years ago but, i really used to new software and many times, i use that new software. For example, the last scientific comes with kde 4.3 .

But, by the way, I think this problem is not a particular distro related problem as other user right here have stated. it seems to me combination of kde and nvidia drivers, or nvidia driver alone. I think in one month i will upgrade and with more time and i'll test it. Would be great try to catch the problem if it's still there and i will try , for sure.

The memory leak is fixed when I use kde 4.6 + nvidia 260.19.36

It use to leak to more than 20% of the my RAM (400MB) in few hours (especially when playing videos and suspending) now it never goes beyond 7,5% in more than a week. I run this combination for a month and I'm pleased not to have to restart X every day.

I didn't mention that, i keep my system on many hours and used to suspend to ram many times and clearly just returning from suspended state increases X memory usage. Usually i don't watch videos, my problem isn't related to that.

So, I updated my system yesterday, right now i'm with 2.6.35.11-83.fc14.x86_64, kde 4.6.1 and nvidia driver 260.19.36.

After one day of full and typical usage,i can say that X server memory usage is better than before, without doubts, it keeps lower, around 50-100 mb with normal use and it increments by workload after many hours, but much less than before and it keeps around 200-400mb with intensive use (firefox-chromium with dozens of open tabs and many okular plus lyx-libreoffice).

But,but, unfortunately, there still is a quite clear problem returning from suspended state. X server memory usage before suspending, 50MB, after that it returns with 200MB. Other time, before 70, after 130MB. I understand there could be a difference, but it's not normal an increment of at least 100% just by waking up from sleep. Something is wrong with that. Clearly it's not so serious as used to be but nevertheless it seems to be there.

Maybe during this week can do more detailed test and give a more precise opinion after few days of use. Perhaps i can use the new(for me) feature from ksysguard "detailed memory information" and xrestop. Some help to give a more precise memory usage information?

fyi - I don't suspend but I do hibernate and my X server memory is about 196mb

ksysguard "detailed memory information" :

The memory usage of a process is found by adding up the memory usage of each of its libraries, plus the process's own heap, stack and any other mappings.
Private
196296 KB [heap]
1188 KB /usr/lib64/xorg/modules/updates/drivers/nvidia_drv.so
1184 KB /usr/bin/Xorg
212 KB /dev/nvidia0
140 KB [stack]

This is what i find before suspend and after return:

Before
private
73812 KB [heap]
3596 KB /dev/nvidia0
884 KB /usr/bin/Xorg
576 KB /usr/lib64/xorg/modules/drivers/nvidia_drv.so
408 KB /dev/zero
276 KB /usr/lib64/nvidia/libnvidia-glcore.so.260.19.36
200 KB /usr/lib64/xorg/modules/extensions/nvidia/libglx.so.260.19.36

After
Private
135540 KB [heap]
3596 KB /dev/nvidia0
1392 KB /usr/lib64/nvidia/libnvidia-glcore.so.260.19.36
1164 KB /usr/lib64/xorg/modules/drivers/nvidia_drv.so
1088 KB /usr/bin/Xorg
224 KB /usr/lib64/xorg/modules/extensions/nvidia/libglx.so.260.19.36
136 KB /dev/zero

The change in memory usage is obvious, but still it's very low, long away from my previous scenario . During these days I've kept my system around 1GB, since kde 3.5 that i didn't see this.

During those 6 months I tried successfully various nvidia (260.x to 270.x) and KDE SC (4.6.x to 4.7.0) combination. It doesn't leak as before, still X memory usage hovered around 100-120 MB just after displaying videos are many images or flash. This doesn't happen with an integrated HD3000 Sandy bridge GPU.

And today, I tried the Raster QT graphics engine. And X has now a normal memory usage of 40-60MB . (same as gnome2 + compiz on the same computer, and same as a HD3000 GPU).

So probably switching to the raster graphics engine will help your memory leak.