100% / disk usage ?

I got very freaked out today that my / is 100% used. I did not know why and this was really annoying since my program couldn't load due to not enough temp space.

$ df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda1             19615736  18618140      1168 100% /

I googled a while and noticed many people mention it is because of some stupid backup program. But, I didn't use it.

So I focused on what I have downloaded since yesterday. Oh, I figured out, it must because of the phoronix-test-suite. I checked their doc and deleted its files under my home directory. And things became good again.

So, if you get the same trouble, just think what you have downloaded *unintentionally*.