Adventures in AIX CPU babysitting
In a recent adventure, I became interested in measuring CPU usage on AIX. I don't have the benefit of professional help or third-party monitoring. I also rarely trust either of these things when they're available, because either one can have trouble describing what's actually being measured. On any system, there are lots of pitfalls to consider when a laymen starts wondering about CPU usage. On AIX, there are some unique pitfalls. What's being measured? To determine the health of a system, you might quickly check the overall CPU usage to make sure it's within some tolerance. But once a system is unhealthy, you'll often quickly need to focus on individual process usage. Sometimes, the process-level statistics are presented in ways very different from the system-wide. Sometimes this is simply because different tools are used -- whether the calculations, meanings of fields, or just the sampling intervals are different. Something as simple as ...