Indicator – Fix System Load Indicator Only Shows as a Line Unless Hovered

Yes. They are a complete different thing, even the opposite in a lot of ways. I will try to explain both simply and short. Note that this answer are just a simplification and the real thing is quite more complex. Click on the wikipedia links for a better explanation.

• Disk Cache memory: This are chunks of the physical memory, the RAM, used to store files. That way when a program needs to read the file, it's fetched from memory instead of the hard disk. This is done because memory is way faster.
• Swap: This is a place on the hard disk (usually a dedicated partition) that is used to store programs or data that can't fit in memory, like when a program grows more than the available memory. SWAP is way slower than RAM, so when you hit swap the computer gets slower, but at least the program can work. In linux swap is also used to hibernate, or to move low used program out of memory to allow more space to the disk cache.

This is for Ubuntu 14.04 and later.

1. Install indicator-sysmonitor

   sudo add-apt-repository ppa:fossfreedom/indicator-sysmonitor
   sudo apt-get update
   sudo apt-get install indicator-sysmonitor
   

2. Run it

3. Click on its indicator → Preferences → Advanced tab
4. Change label from cpu: {cpu} mem: {mem} to cpu: {cpu0}{cpu1} mem: {mem}. Add whatever as CPU cores you have.

5. Save

   

References:

• Ubuntu AppIndicator That Displays Bash Scripts Output On The Panel: Sysmonitor Indicator