Why is Ubuntu 14.04 using too much RAM..? [closed]

I believe I just had the same problem and have now resolved it for myself. I believe that this issue is swap related.

I have also recently reinstalled 14.04 on whole disk and was previously using 13.10 successfully and well. I too noticed my that my ram was mostly staying around 1.2GB of use, just as stated in the person's question. I strongly suspect that the person probably used whole disk encryption which is a part of the Ubuntu install which likely caused this issue.

My symptoms were that occasionally Ubuntu would become almost complete unresponsive even with a typical light amount of open programs and activity, which had been performing acceptably on my old Ubuntu install. At first I thought it was Firefox or Software Center related.

Dell Optiplex 780 (small form factor/sff)

Pentium(R) Dual-Core CPU E5300 @ 2.60GHz × 2

Memory 2GB (plan on upgrading to 8 or more very soon)

Video Intel® Q45/Q43

I noticed in the System Monitor program, that in the resources tab it showed swap as "not available" (or something along those lines). This was a fresh install of 14.04. I used whole disk encryption, and decided it was probably related to that. I checked for the existence of my swap partition in the Disks program, and saw that the swap partition did exist at least and seemed appropriate. It was called: /dev/mapper/ubuntu--vg-swap_1 which is correct.

I also confirmed it's existence in terminal with:

sudo fdisk -a

I did some googling and decided it may not have been activated as swap, even though the space was created, so I deactivated swap:

sudo swapoff -a

Then I told it to recognize that space as swap:

sudo mkswap /dev/mapper/ubuntu--vg-swap_1

Then I turned swap on:

sudo swapon -a

I then received a message about cryptsetup swap blah blah blah, which is appropriate, but I did NOT receive a message regarding /dev/mapper/ubuntu--vg-swap_1, despite having received one before I did these steps.

I reopened System Monitor and saw that it does indeed now recognize and use my swap space. Just for good measure, I restarted my computer, and it has been running quickly and normally again, just like before installing 14.04.

I think I may not have even noticed many problems had I not had such low RAM, which makes having swap space activated quite important.