Memory goes crazy (in KDE?)

[Gerenuk]

My problem is that some applications seem to overconsume memory and not release it after closing down. I'd like to detect what's going on.

I do use too many tabs in firefox, but still somehow it's exceedingly greedy. Also not all space gets freed if I close firefox down!

Moreover, I found a curious behaviour. I tried composing large images (10x A4 300dpi) into a 15MB PDF file with imagemagick and the process went crazy and consumed *all* memory until it got killed. That happened repeatedly. Whereas logging in on a normal console without X was absolutely fine.

I have ArchLinux, KDE 4.3.4, 1GB RAM, 300MB Swap.
I checked the RAM with memtest.

So basically I first would like to know which processes consume how much of the memory?
Then I'd like to know why the memory is still occupied (as shown by "free") after I close down the program? And who keeps that memory (for example the firefox process is really dead, but memory still scarce)?
Could there be some funny error or leak that makes processes endlessly allocate memory - more than they need?

Can anyone suggest a method to examine my problem?

[elija]

Linux will do that. Some of your memory will be taken up for caches and buffers and some will be used to keep recently run applications handy for a quicker start the nect time you use them. It will be released when needed.

It makes sense if you think about it. There's no point having memory in your computer that isn't being used.

[Gerenuk]

That memory isn't easily released. The memory seems to be full with memory not get released and the system is slow, before I don't get a major crash somewhere.
So I wish to find a way to release that memory. Especially if it's firefox using all of the 1GB RAM and I plan to do some image editing after closing down firefox.

Also my actual question is how to spot who owns which memory.
It's not good if a program allocates far more memory than it can possibly need.

[elija]

I would expect to see very little memory free on a Linux box especially if it has been used for a while. On my 4gb box, I can get upto 80% used over a weekend depending on what I do. It's currently at ~75% so it has been a varied and pretty heavy weekend of use

FF used to have a memory leak but I think it was plugged in 3.5.

Troubleshooting Memory Usage - RimuHosting may help with your troubleshooting

[bigtomrodney]

Memory management is different in Unix-like systems such as Linux. You do not need to be concerned about memory as you may have been in Windows. The memory management is much more advanced and will cache applications as needed, freeing it again when it's required. There are a lot of articles online about how it works, all in all though you can trust your system to look after itself.

[coopstah13]

I don't know how you are checking memory, but you should use free -m command and pay attention to second line

Mem:          2026       1114        912          0        264        422
-/+ buffers/cache:        426       1599
Swap:          478          0        478

this is my laptop currently, only 426mb is actually used, but it seems like i'm using 1gb

[elija]

I would expect to see very little memory free on a Linux box especially if it has been used for a while. On my 4gb box, I can get upto 80% used over a weekend depending on what I do. It's currently at ~75% so it has been a varied and pretty heavy weekend of use

FF used to have a memory leak but I think it was plugged in 3.5.

Troubleshooting Memory Usage - RimuHosting may help with your troubleshooting

Should have added that most of my memory use is buffers and cache

[Gerenuk]

Hmm, I've just had his problem again

The memory is really *not* released after I close down firefox (as shown by gkrellm). Also the systems really slows down and crashes when the memory fills up even more.

Any ideas how I can detect what's going on?
Or the the disproportion between memory and swap size an issue?

PS: I do not wish to fix firefox and also the problem is real.

[coopstah13]

post output of free -m command

[Gerenuk]

I need to wait until I get the no release problem, but first I just had another very annoying problem (maybe that's actually the origin of all that).

With firefox I had

             total       used       free     shared    buffers     cached
Mem:          1009        966         43          0          0         20
-/+ buffers/cache:        946         63
Swap:          235        235          0

After closing firefox down I had

             total       used       free     shared    buffers     cached
Mem:          1009        729        280          0          2        116
-/+ buffers/cache:        609        399
Swap:          235        232          3

Btw, apart from KDE I have nothing else running now.

Anyway, I just restarted firefox. Now the big problem was: When I had firefox running and the swap down to 0MB, the system started accessing the harddrive endlessly. The free RAM *fluctuated* around 80M for a very long time even though I didn't do anything new on the computer. As if the swapping algorithm was broken.

Now with 1MB free swap the harddrive occationally rattles for no reason and everything I start makes it go crazy again for a moment. All in all every operation now is slow since the harddrive gets busy

Any ideas why having zero swap is so bad and an irreversible issue?