Watch System Activity and CPU Usage from the Mac OS X Dock

Activity Monitor can be used for more than just managing tasks and killing processes, it can also turn the Mac OS X Dock into a live system monitor where you can keep an eye on processor usage, CPU history, network activity, disk activity, or RAM use.
- Launch Activity Monitor, found in /Applications/Utilities/
- Right-click on the Dock icon and scroll up to the “Dock Icon” submenu and select one of five available options:
- Show CPU Usage – this is a live gauge of processor activity on the Mac, each CPU core is shown as a separate bar, this is probably the most useful of the five choices (shown up top)
- Show CPU History – this shows processor load and use graphed over time, each CPU core is shown separately
- Show Network Usage – displays a graph of incoming (green) and outgoing (red) network traffic, this can be helpful if you’re on a sketchy internet connection or are carefully conserving bandwidth
- Show Disk Activity – shows a live graph of disk reads (green) and writes (red) in the same format as Network Usage
- Show Memory Usage – displays a pie chart of current RAM usage and allocation on the Mac, green is free memory, red is wired, yellow is active, and blue is inactive memory

If you find yourself using this often, you may want to pin Activity Monitor to the Dock by right-clicking and choosing “Keep in Dock” from the Options submenu.
Here is what the memory usage pie chart looks like:

And here is what Disk Activity and Network Activity look like:

If the Dock isn’t your thing, the iStat Menu bar item offers similar features in the menu bar.
Thanks to Roman for the tip idea

Hi
Neat tip and it suits the blog.
However I find using Geektool (free) and a few scripts (found online) better – I currently have CPU usage monitored, memory usage (& found through this that something I use or OSX itself has a memory leak, and hard disk usage
Strange, I have a quad core i7 Macbook Pro and I can only see 1 core displayed and not 4 cores as in your article.
On top of that there is no activity whatsoever in the graphical representation in the dock.
Are there any other parameters to look for?
Mac OS X 10.7.3 Lion
Macbook Pro 15″ 2.3 GHz Intel Core i7
It shows up on my Core i5 MacBook Air as 4 cores despite being a dual core machine, I think in your case it might be interpreting your quad core as 8 cores due to hyperthreading (4 core + 2x hyperthreading) and there’s not enough room in the Dock icon to display 8 bars so it only displays 1. Activity is visible if you pegged the CPU hard enough, but consider that it’s reading 8 as 1 the overall load is dispersed widely across the 8 threads and therefore shows virtually no activity. Do something CPU intensive to verify this of course, but you can also select the Monitors > CPU Usage to display a floating window which will display each CPU core use.
If you have Lion, then that is normal. Using the kernel’s multithreading technology it displays all cores as one (windows 8 does this as well).
One way to prove it is download something like handbrake and have it encode a movie, and you will notice it will surpass over 100 percent on the CPU cycles (for my 2011 macbook pro it went over 600, meaning it have approx 6-7 cores in use)
THX!!!!
I use MenuMeters by Raging Menace. Very customisable. Displays in the menu bar rather than the dock, but provides details on pretty much anything you’d want to know.
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