Activity Monitor itself also consumes a lot of CPU. And you tend to only use it when you've already suspected a problem, like when your fans start running.
What's nice about having a global CPU graph is that you get used to normal idling levels and will start to notice anomalies.
You're also just closer to the pulse of your computer. What exactly are normal bandwidth consumption levels over the course of a day? What speeds are you normally getting? Which apps and which actions seem to be the hardest on your resources? I think these are just nice things to know about the device you use every day like how you might get used to the sounds and feel of the car you drive every day.
For example, I often see HNers suggest that a good computer confers no benefits for web browsing. Meanwhile, I can say that web browsing is the most resource intensive thing going on in my computer. What your CPU graph as you click around the internet. Or when decoding a high res Youtube video or a muted autoplaying video on some news article. Or scrolling Facebook/Instagram.
I have an older machine that stutters while playing 720p+ Youtube videos unless the CPU is idle, and busier webpages take much longer to render and lock up the UI before I can click around. A better computer can save an impressive amount of time in the long run. It's not for nothing!
> Activity Monitor itself also consumes a lot of CPU. And you tend to only use it when you've already suspected a problem, like when your fans start running.
MacOS always tracks the energy usage stats so you don't have to keep activity monitor open, just look at the 'Average Energy Impact' column. iStats menu also uses a fair bit of CPU, similar to Activity Monitor, it's just split into a couple processes so it doesn't show as much, not that this is a reason not to use it, I love it and use it daily, it's not a good contrast point with the activity monitor.
My main point is that a global CPU graph helps you identify acute CPU consumption as it happens which is the main mechanism that helps me identify things like Spotify getting stuck in a spinlock or a browser tab devouring my battery. Seeing "Google Chrome" show up in Activity Monitor's energy chart when you check it periodically isn't as helpful.
Good point about iStat Menus consuming its own resources. It has two processes afaict with its main process staying below 1% CPU. I bet that number sees an increase once you start turning on more HUDs like the temp/fan sensors and jacking up the update frequency though.
> My main point is that a global CPU graph helps you identify acute CPU consumption as it happens which is the main mechanism that helps me identify things like Spotify getting stuck in a spinlock or a browser tab devouring my battery. Seeing "Google Chrome" show up in Activity Monitor's energy chart when you check it periodically isn't as helpful.
If you want to know 'what is using all by battery' after a couple hours using it, you want to know the average power usage by app, which activity monitor gives you. Battery life is the point of this thread, not random lock ups.
> Good point about iStat Menus consuming its own resources. It has two processes afaict with its main process staying below 1% CPU.
I wish we could just get rid of 'cpu %' as a metric on modern machines, or at least scale it based on P-state. Saying process X is taking Y% of the CPU is pointless if you don't also communicate the P-state, and chances are you don't even know which core the process is running. Point is, I'm sitting here almost completely idle and there are plenty of tasks 'using 3-5% of my CPU', of course the CPU is running at 800MHz no where near it's all core peak of 2.7Ghz, much less it's single core peak of 4.5Ghz. What does 1% CPU even mean in this world?