Show the processor and memory and storage use by percent, in a compact 1x1 widget. No drain on battery, no spooky permissions, no ads.
When a resource get close to 100%%%% (full), color changes to red. Low pct mean light use, shown in green. Sampling is done once per minute (by clock ticks, not adjustable). Tap on widget to update immediately.
To install, long-press an empty spot on your home screen, select "Widget", then pick our "Usage Widget".
Notes:
CPU measures processor use, ranging from near 0%%%% when sleeping to near 100%%%% when inefficient or runaway processes drain battery and result in sluggish response.
RAM is free memory available to the CPU to run apps and services. When full, Android OS kills idle or "unimportant" ones, such as widgets or backgound services.
INT is internal storage storage is disk space to store apps and their unexported data and cache (temporary files). When that fills, you can't install any more apps. (We don't distinguish /system from /data. Should we?)
EXT is external (removable) storage on the SD card. That's where you save pictures and music etc. EXT is accessible from a PC via the USB charge cord.