Kubuntu 6.06 doesn't use my swap space.

[Alienkind]

I've recently installed Kubuntu 6.06 alongside WinXP on my Dell Inspiron 9300 laptop. So far, I have made only marginal changes to the default Dapper install. I upgraded all the 'upgradeable' packages yesterday on Adept as well as installing qtparted and Gaim (along with whatever dependencies that those 2 apps needed). Everything works really well except for a few wireless networking issues and this other problem I am about to describe.

My laptop has 512 MB of RAM. I allocated 2 GB of swap space during installation of Kubuntu Dapper. However, when I run KSysGuard, it shows my system not using any of the allocated swap space. It reads: Swap space used: 0, Swap space free: ~512 MB. Also, KDE running one instance of Konqueror uses all but about 10-12 MB of my physical memory. Even after I close Konqueror, very little RAM is freed.

[caserio]

Re: Kubuntu 6.06 doesn't use my swap space.

Hi,

It's OK. Swap space is used when the amount of physical memory is full. 512 MB of RAM is largely sufficient for most daily needs.

However, 2 GB of swap space is a good choice when using the suspend-to-ram function.

[Alienkind]

Re: Kubuntu 6.06 doesn't use my swap space.

A correction to my original post: KSysGuard says that I have ~1.5GB of swap space free.

Actually, no. This is not OK. I know this because when I installed Ubuntu 5.10 and when I upgraded Ubuntu to 6.06 before. A cetain amount (nonzero) of swap space was always being used. Now that I reformatted my hard drive and installed Kubuntu, I get this swap space problem. Kubuntu detects that I have allocated 2 GB of my hard drive to use as swap space, but isn't using it at all. Instead, My previous setup with Ubuntu 5.10 and then 6.06 needed to use swap space.

I even tested out the caserio's hypothesis (that 512 MB is enough) by opening some pdf files simultaneously in different tabs in Konqueror. Each of these pdf files is about 900 MB in size (!) and opening one of them alone uses about 60 MB of RAM. I opened enough of these files to easily surpass my 512 MB of RAM. To my surprise, KSysGuard started showing varying amounts while I opened up the files, sometimes even increasing the free swap space. I think Kubuntu just ditches some memory info here and there without interfacing with my swap.

Do not tell me that Kubuntu with KDE uses less memory than Ubuntu with Gnome. Even as a Linux newbie, I at least know that. Something is wrong with memory management for sure here.

[Alienkind]

Re: Kubuntu 6.06 doesn't use my swap space.

I played around a little more with my system. KSysGuard shows me that after I have about only 3 MB of physical memory free, older data is cleared from memory. Never is there a change in "Swap: 0 KB used, 1,574,360 KB free" .

[Alienkind]

Re: Kubuntu 6.06 doesn't use my swap space.

I was trying to say that I know that Gnome has a smaller footprint than KDE in my second post. I just realized that that statement could easily be misinterpreted.

[kubicle]

Re: Kubuntu 6.06 doesn't use my swap space.

Do not tell me that Kubuntu with KDE uses less memory than Ubuntu with Gnome. Even as a Linux newbie, I at least know that. Something is wrong with memory management for sure here.

That's relative, on my system gnome leaves a bigger memory imprint (It mostly depends on the services/programs you're running...the memory needed by gnome and kde are roughly the same)

Actually, no. This is not OK. I know this because when I installed Ubuntu 5.10 and when I upgraded Ubuntu to 6.06 before. A cetain amount (nonzero) of swap space was always being used.

After a fresh reboot to kubuntu swap space is not necessarily used, here's the output of free from my machine (after a fresh boot to kde):
             total       used       free     shared    buffers     cached
Mem:       1034648     269360     765288          0      11824     146956
-/+ buffers/cache:     110580     924068
Swap:       979956          0     979956

I even tested out the caserio's hypothesis (that 512 MB is enough) by opening some pdf files simultaneously in different tabs in Konqueror. Each of these pdf files is about 900 MB in size (!) and opening one of them alone uses about 60 MB of RAM. I opened enough of these files to easily surpass my 512 MB of RAM. To my surprise, KSysGuard started showing varying amounts while I opened up the files, sometimes even increasing the free swap space. I think Kubuntu just ditches some memory info here and there without interfacing with my swap.

It's possible kubuntu is just freeing the memory used by cache/buffers to accommodate the need for more ram for apps...if the swap isn't working and you use up all your available ram you will run out of memory...has this happened?

[caserio]

Re: Kubuntu 6.06 doesn't use my swap space.

What is the output of this command ? --> cat /proc/swaps

Tip: use qps for monitoring your system. It's more reliable, complete and faster than ksystemguard.

[Alienkind]

Re: Kubuntu 6.06 doesn't use my swap space.

Okay. Now I think I understand. I guess Linux does not need to constantly use swap space as I expected to. (WinXP is always using pagefiles even if I have more than enough physical memory). Also, I found that my Kubuntu started to use up about 18 MB of swap when I was running a few large files last night in addition to installing ubuntu-desktop in Adept. So I guess I was terribly mistaken.

BTW, is there a difference between swap space and page files? Also, what technically is virtual ram? Is it one of the aforementioned? Any site on the web good for learning how computers use memory?

Thank you.

[binary2k2]

Re: Kubuntu 6.06 doesn't use my swap space.

BTW, is there a difference between swap space and page files? Also, what technically is virtual ram? Is it one of the aforementioned?

not much difference between swap and a pagefile, just a pagefile is a file (duh) on the filesystem that is used as virtual ram (virtual ram is the pagefile) and Linux uses a seperate partition for it. Although Linux can use a swap-file which is the same as a pagefile.