Tweak System Monitor in Ubuntu to Get Accurate CPU Usage Readings of Processes (tip)

The system monitor that comes with Ubuntu shows the CPU load of individual cores (if you have a multi-core processor) when you click on the ‘Resources’ tab. If you want see the actual processes that use your CPU cycles (usages) by clicking on the ‘Processes’ tab, then there too it shows processes and their CPU usage using the same method.

However, if you are not really a geek ;-), then the CPU readings in the ‘Processes’ tab might get you confused, when you compare it with the CPU usage reading on the ‘Resources’ tab. For instance, let’s say that I have a processor with 4 individual cores and one of my programs started to use 100% of the first core (let’s call this process; ‘burnP6’).

The system monitor will still show it quite accurately on the ‘Resources’ tab (as the first core is running at full throttle, 100%), so in truth, in this occasion, that application should be consuming 25% of the ‘whole’ CPU power (because only one of the four cores is running fully loaded).

But, if I clicked on the ‘Processes’ tab to see the actual process that is consuming the CPU, then it will show its CPU usage reading as 100% (as shown below).

This is not a bug or anything nor there’s anything technically wrong with it, plus, advanced users can always guess what is happening too. But again, for a non-technical individual, this can be confusing and less ‘intuitive’.

So instead, wouldn’t had it been better, if the processes shown in the ‘Processes’ tab were listed, after dividing their CPU usage by the total number of available CPU cores ?

And if that was the case, then in this occasion, the process that had been consuming 100% of the first CPU core (‘burnP6’), would had been listed as of using 25% of the total CPU power in the ‘Processes’ tab, instead of the somewhat misleading ‘100%’.

Now I’m more than certain that most users do know this. But if you are someone new to Ubuntu, and looking for a way to make it happen, then luckily, there is an option (disabled by default) that does exactly that. For that, please follow the below steps.

Step 1: First open the system monitor in Ubuntu (search for ‘system monitor’ in Dash).

Step 2: Once opened, from the menu, go to: ‘Edit’ -> ‘Preferences’.

Step 3: This should open another new window. From this window, make sure you’ve selected the ‘Processes’ tab.

And then, as shown below, look for an option called ‘Divide CPU usage by CPU Count’. Once you have found it, enable it by simply putting a check-mark in front of it, and close the window.

As soon as you do that, under the ‘Processes’ tab, again for this process called ‘burnP6’, this time it will be shown as of using 25% of my total CPU power, which feels more ‘accurate’ (same will be applied to all other processes, of course).

Note: Not that it counts for anything, but Windows system monitor also uses this approach …

That’s it!.

2 thoughts on “Tweak System Monitor in Ubuntu to Get Accurate CPU Usage Readings of Processes (tip)

  1. I do that but i still get high inconsistencies between the resources and the process panels. For example my resources may show that both my cores are being used to 100% while my process panel would only show processes than use less than 30% aggregate CPU usage (mainly when firefox and dropbox are running).
    Any clue as to why?

    • Hi Andrea,

      Maybe in the ‘Process’ tab the system monitor is set to display only your processes (‘My Processes’). If that’s so, then change it to show ‘All Processes’. That may help…

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