Gkrellm reports memory and ramdisk as disk writing

Hi,

This tool is great.

I've noticed disk activity when I watch live stream or youtube
video. It's very obvious on Gkrellm.

When I stop live stream disk activity stops.

However I though I can make my browser use memory only for cache
storage to save the disks some unnecessary writes.

In Firefox I set

browser.cache.disk.enable;false

But GKrellM was still reporting a disk activity even though I set it
to monitor sda only

Then I tried chromium browser with a ram disk with the following
commands:

sudo mount -t tmpfs -o size=1024M tmpfs /media/ramdisk/

chromium-browser --user-data-dir=/media/ramdisk/

But I still see reported disk activity. So I wonder why this is
happening and if I can limit the activity to only what makes the
disk spin.

Thank you,

Usama