How much memory does PCLOS need

[keith.78201]

I'm having a similar problem using PCLinuxOS 2011.  I'm using a notebook with 1GB RAM and when I use Solaris Studio 12 with Okular running to read a software documentation pdf the machine always goes into swap thrash within a half hour of starting work.  User interaction DIES and I wait five minutes for it to recover. I'm able to get System Monitor working and the graph of RAM and Swap use shows about 25% RAM use with an equal amount of Swap use in MB. 
Question:  Is there a configuration option which fixes this absurd use of swap at only 25% RAM use.  Swap should not even become active until at least 75% (at the low end) of RAM is used, 90% is more reasonable.  The original poster on this thread asked if they needed to buy a NEW MACHINE, for god's sake.  Do these Kernal implementers know this?  Are they selling hardware?
P.S. I don't now and have never worked for MicroSoft.

[djohnston]

 
Question:  Is there a configuration option which fixes this absurd use of swap at only 25% RAM use.  Swap should not even become active until at least 75% (at the low end) of RAM is used, 90% is more reasonable.

There is an article with an index of the Linux kernel mailing list on setting swappiness values here. I realize it's from 2004, but the subject matter covers the basics of setting swappiness and what the values should be. In a nutshell:

To tune, simply echo a value from 0 to 100 onto /proc/sys/vm/swappiness. The higher a number set here, the more the system will swap.

If you look at the default settings for PCLinuxOS, the value is already set to 0, which is the lowest amount of swapping activity.

cat /proc/sys/vm/swappiness
0


To change the system swappiness value permanently, open /etc/sysctl.conf as root. Then, change or add this line to the file, (where xx is a value from 0 to 100):

vm.swappiness = xx

Reboot for the change to take effect.

You can also change the value while your system is still running, by running as root (where xx is a value from 0 to 100):

sysctl vm.swappiness=xx

And you can clear your swap by running swapoff -a and then swapon -a as root instead of rebooting.

[kjpetrie]

How big is your swap partition? If it's 4GB, 25% swap represents your whole RAM, for instance. What matters is not how much RAM is in use after swapping, but how much was in use before swapping. If a temporary surge in demand needed a large swap, and then that RAM was released, what was swapped will stay swapped until it's needed, as swapping it back would just tie up resources.

Solaris Studio 12? Is that in the repo? I can't find it if it is. Using outside applications is not recommended as it will break your system and cause unpredictable behaviour which can't be supported here.

Also, it wasn't clear whether your system is fully upgraded. Partial or selective upgrading will also cause unpredictable behaviour and ultimately render the system unusable.

None of these things are faults in pclos.

[gseaman]

I've experienced this occasionally when several tabs of flash content are open in firefox, or when moving several gigabytes of data in konqueror. I only have 1gb, so I accept that this is the result of my overuse of the hardware. I can open dozens of programs without any system delays, it only occurs when memory is overtaxed. I'd say get 4gb and the problem will be mostly solved. Only when flash is dead will the problem be completely solved.

Galen

[T6]

this post is being oriented away from the original question or maybe it wasn't the original meaning of the question

how much ram do you need to run pclinux 2012 with kde4?  i could boot my pc after the os was installed with just 256 mbs of ram

i have run livecd with 512 mbs of ram, 32 of those mbs were used for the onboard video card

ideally 1 gb should be enough for most uses with very little to no swap usage

if your web browser usage makes you use lots of pages simultaneously this will make you use lots of ram, no matter the os or the desktop environment in use, this also happen on windows

eventually all the ram is used and swap is used later

to avoid this situation, 2 gbs of ram should help alot, 4 sounds like perfect, 8 like a dream to me

personally i don't have use for 2 gbs yet so anything over that seems like a distant future to me

at the moment my netbook with 1 gb shared with the intel onboard video card does all what i ask and it seems that swap has not been really used in the whole morning it has been on, just verified and system used 18mbs of swap(of 3000 i gave when i installed the os, what a waste    )

opera atm uses 140 mbs of ram and i have opened countless pages that remains cached to be reopened as fast as possible

free command reports that i'm using 840 mbs of the 1 gb i have but my desktop widget says that i'm using 500 mbs only, we talked about memory usage in another post with excellent explanations on how ram is used and reported by different apps

[gilado]

I have tried to turn off swap altogether. It just moves the problem as ff and tb start fighting over memory and eat the file chache file buffers.

I also setup a simple test: disable all plugins and extensions in both Firefox and Thunderbird. Disable auto get mail in Thunderbird. Start Firefox with a blank page (initial memory usage ~100MB.) Start Thunderbird (initial memory usage ~90MB.) Let them sit idle; in fact, let the entire machine sit idle.  Watch how every few minutes each of them gobble another 2~2MB. After a few hours of idle time they double their memory consumption and triple their virtual address use.  Tested with ff 11 and tb 10

Opera is much more well behaved. I use it whenever I can. But I don't a have a good replacement for tb.

PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
 8915 user       1   0  573m 193m  18m S  0.3 19.3   2:16.49 thunderbird-bin
23978 user       4   0  509m 126m  27m S 22.9 12.7   4:00.79 firefox

[keith.78201]

Thank you for the help.  My swappiness configuration parameter is set to 0, the default, which means that there is no way to fix this problem. 
To the person who suggested that upgrading particular components could cause the system to fritz:  Have you heard of modular design?  You seem to be of the school of thought that made Microsoft rich for adopting open systems architecture as their standard.
If swap comes on at only 35% of RAM use on the lowest "swappiness" setting, there is a problem.  I think I'll write a memory allocation and paging system which solves this problem and submit it for review (as soon as I'm done with my current C++ project, implementing the SHA-1 hashing algorithm) .
Thanks again,
Keith

[kjpetrie]

I was talking about software, not hardware. pclos is modular in the sense you can install or remove components, but you must upgrade it as a whole. As components are upgraded their dependencies change, and these must also be modified to suit. Otherwise incompatibilities will arise which will prevent proper operation. It's nothing to do with attitude and everything to do with practical necessity. It's what keeps a dynamic distribution reliable and stable.

Please read http://www.pclinuxos.com/forum/index.php/topic,42874.0.html.

[keith.78201]

Thanks, I thought perhaps we were back in the tech-lock economic protection age before modular design was adopted as a desirable goal in software development.  I haven't actually read any of the linux source code, so I'm completely unfamiliar with how it is architected, except perhaps in so far as it is similar to Unix, which I studied in college.
I've changed my mind about the implementation language of the memory allocation system I'm going to work on and submit: Objective C is a far better choice, and I'm studying GNUstep as a possible development platform.  My reasons are that I can produce code which is more secure than that possible with C or C++.