Like any curious computer user, I wondered one day as to just how my system reacts to my daily usage over a long period time. I figured it would be neat to make a nice, simple plot of my system's long-term memory usage and CPU usage. So, I found the IRIX system tool "pmkstat", which stands for Performance Metrics Kernel Statistics, and piped its output to a text file, on a 5-second interval, from January 20th to March 4th. After some minor parsing of the text file, I was able to grab the pertinent information related to RAM and CPU usage, then using C++ and OpenGL, I plot it to a window (Figure 1).

Figure 1, Click to Enlarge

There are definitely some interesting periodic features in the graph. You can see a long period in the CPU usage graph where it is mostly idle, as I was on vacation for that period of time! I'm mostly curious as to what caused the three 'chunks' in the CPU usage graph directly to the right of the idle period. It appears the cpu idled at around 30-40% usage for long periods of time (nearly a day?). Perhaps this is from IRIX's fsr_xfs utility (kind of like defrag) running periodically, or maybe some other maintenance.