Digikam & xorg heavy cpu load

**JoergJaeger** · 26-Oct-2010, 20:49

Well, i did not have really time to do a testing, but i will do it tomorrow with some starting, closing and full load.
I have to get more into the commands and the broader knowledge of how the memory is utilized under linux. Just from seeing the numbers in top you can think of how the memory shrinks, but i think it is not.
What i did is to limit the caching somewhat to increase the swappiness to 100.
In a way, i am amazed what you can do with linux which would be more difficult under windows. Just by the commands you have. Very, very useful. The only thing i really miss, i think i mentioned it once, is a tool that can show what a program is actually doing. I remember i had a tool as i had an Amiga. It was called snoopdog. With that it showed the process of a program and processes overall. So you were able to pinpoint if a program make crab or died. Pretty sure there is something like that in Linux. Just haven't found it yet.

I'll highly appreciate any tips and helps.

**consused** · 27-Oct-2010, 06:14

BTW, you can use the command "free" to display your system's memory, including cached memory and buffers used by kernel. But note the shared memory column is obsolete. For example:

Code:

free -m

displays it in megabytes (easier than "top", to read quickly):

Code:

             total       used       free     shared    buffers     cached
Mem:          2883       1011       1871          0         41        615
-/+ buffers/cache:        354       2528
Swap:         2047          0       2047

See the man page for a few more options. Although not mentioned, "free -g" will display in gigabytes, but you get zeros if less than one GB.

**JoergJaeger** · 27-Oct-2010, 15:06

I checked my memory of a period of time and came to the conclusion that the ram is used the same way, regardless what program i use.
In the end, my cache is always around 2,5 GB and my free Ram about 300K where the total ram used is about 3,7GB. It uses about 300K in Swap.
Do you really need swap anyway?
After start there is of course more ram left, normally about 3GB free.
I assume that this is a normal pattern and if not, why is behaving like this on my computer. I really only have a standard computer (self build). Next year i will build perhaps a newer computer and upgrade the motherboard and ram.

**JoergJaeger** · 27-Oct-2010, 17:01

Just one more question. I usually have the following programs loaded automatically. Akregator, Kopete, Skype. Also i run firefox & thunderbird. Occasionally i use Amarok & Digikam. The reason why i am listing these programs, is that after a long time my system uses swap so i assume i need more ram to run all these programs without using swap.
First, am i right? And secondly is this normal for a system having 4GB of ram.

Thanks

**consused** · 28-Oct-2010, 02:00

I don't have 4GB of ram, only 3GB and I would expect to run all those apps (I don't run all of them now). On an older system (1.8GHz single ccpu) I only have 1.5GB, that runs KDE 4 on 11.2 and 11.3 better, and I use integrated graphics chipsets which take up memory. However when firefox is streaming a larger-sized, windowed Flash video stream, on the older system, most of the cpu resources are used up, full-screen is impossible, and I wouldn't be doing much else.

In your case I think it will depend on what you are running in firefox and digikam concurrently with the other apps, and whether digikam is leaking memory or releasing it. The more concurrent apps you open, the more memory will be taken up, and less will be available for those apps that dynamically require additional memory to complete intensive tasks. If it becomes a problem, you can either control peak usage by observing the memory each task is allocated (using top) and closing those apps temporarily that are not needed, or by adding more ram. It's your choice to make.

IIRC, I read elsewhere that if a swap partition is configured, at some point linux will use it for efficiency, even if it hasn't used up all of the ram. Swapping is only a problem when it produces a significant overhead/bottleneck for the cpu(s) and/or disk. In that case it's easier and probably cheaper to mitigate the disk situation, buying extra disk and moving the swap partition.

On balance, no I don't think you are right with your assumptions in that last question. However, if cost isn't an issue, you must have everything running with high performance with no swapping ever, and you don't mind running inefficient applications, buy more ram.

**consused** · 28-Oct-2010, 02:32

Originally Posted by yester64

I checked my memory of a period of time and came to the conclusion that the ram is used the same way, regardless what program i use.
In the end, my cache is always around 2,5 GB and my free Ram about 300K where the total ram used is about 3,7GB. It uses about 300K in Swap.
Do you really need swap anyway?
After start there is of course more ram left, normally about 3GB free.
I assume that this is a normal pattern and if not, why is behaving like this on my computer. I really only have a standard computer (self build). Next year i will build perhaps a newer computer and upgrade the motherboard and ram.

Sorry, i've answered your last couple of posts in the wrong order. Saying "regardless what program i use", doesn't tell me whether you significantly increased the number of concurrent apps/tasks to stress the system and change the normal patten.

Yes it probably is a normal pattern for your configuration (including disks). My impression with cache (disk) is that once it decides how much of free ram to initially allocate, it never falls below that level unless it's needed by additional tasks.

With small 300K margin remaining, your ram is effectively, and efficiently, fully utilized. Also 300K in Swap is just noise level and not worth worrying about. What do you think will happen to your running system if your real memory runs out without the ability to swap? Think about it.

**JoergJaeger** · 28-Oct-2010, 15:55

At least i know that it is a normal behavior and so i don't need to worry.
No, i am not worried really about swap, just thought that 4GB is a lot of memory. But yes, digikam takes a lot of memory by itself when used.
I was planning to buy or build a new pc (smaller) and get rid of my GT8800. If i do this, i will put more ram in since i do video and more ram can never hurt.

**consused** · 28-Oct-2010, 16:30

4GB seems a lot of swap memory when you are hardly swapping. I decided to only use 2GB for my 3GB of real memory, and that still works for now, even bearing in mind that Hibernate (to disk) uses Swap for persistent storage.

Good luck. I am sure your present system has quite a bit of useful life left in it.

**JoergJaeger** · 28-Oct-2010, 18:19

Since my psu burned up during hibernation under windows vista, i do not use this feature anymore. Bad experience i suppose.

Its not that i think my cpu is to slow, i just want to build a smaller pc for myself and by doing that upgrade everything. This time i probably will use AMD instead of Intel and, like i said, use 8GB. The other cpu will be used by my wife then.

**JoergJaeger** · 31-Oct-2010, 16:51

I found a good read in regards to Linux memory management. If someone mind, i post it. It helped me to understand it a little more.

Low On Memory - linux-mm.org Wiki