Monitoring Processors and Processes

Processors: Introduction

System Monitor can monitor the current load running programs put on the central processing units, the processors of your computer. If the load per processor is at 100%, this processor will be fully utilized, so it will be running all the time, without any interruptions. If the load is at 50%, this will mean there was not enough to do for this processor: After half the time available, it was “finished”, having completed all tasks, or it had to wait for data from other, slower devices, e.g. the hard drive, so it was idle for the remaining 50% of the time interval measured. Modern processors are actually shut down during these idle times which saves energy and significantly reduces operating temperature.

If you like to monitor the load of the system, perform the following steps:

1. Ensure the control window of System Monitor is open.
2. Select the item Information Sources > Processors in the sidebar.
3. Make sure the check mark Monitor this item is set at the right side of the window.

When this option is enabled, the total load of the system will be shown in the menu bar. This is equivalent to the average value of the load of all available processors. In case all available processors are fully utilized, the total load will be 100%. If you had 4 processors, for example, one is fully utilized, and the other three are idle, total load would be 25%. Alternatively, you can configure the display to show the individual loads for each single processor (see below).

The data shown is calculated live and updated about once per second.

Processors: Menu Bar

The box Menu Bar controls in which form total load should be displayed. System Monitor offers a variety of icons and functions that you can combine in any order. The following elements can be used:

• The label CPU (Central Processing Unit) in small, vertical print to designate processor load and to separate it from other icons in the menu bar.
• The label CPU in large, horizontal print.
• The display of processor load as a text in percent.
• The display of processor load as bar chart.
• The display of processor load as pie chart.
• The display of load history for the last 30 seconds.
• A spacer to put more room between items.

Within the box, the upper bar simulates as a sample how this monitor section should be presented in the menu bar. You can grab the individual items by mouse and move them into a different order. You can remove an element by pulling it out of the bar. The lower bar contains the stock of items available. If you like to add a certain item to the menu bar, use the mouse to drag it from the lower to the upper bar. Pressing the button Default causes your current settings to be deleted, replacing it by a default suggestion for the menu bar.

Spacers are shown with dotted rectangles to make it easier for you to recognize and to move them. In the actual display, the rectangle will become invisible, so the spacer does its job providing a blank area within the menu bar.

If you mistakenly have removed all items of this monitoring section from the menu bar, a three-star-icon (⁂, asterism) will appear as a placeholder. This ensures that you still can open the associated menu.

You cannot drag items directly into the real menu bar.

In standard configuration, the menu bar shows the total load for all processors of the computer. You can replace this display by individual displays for each processing unit if you like. All display elements will be reduplicated for each processor in this mode which can consume much more space in the menu bar. The text CPU is hereby replaced by Pxx where xx is the number of the respective processing unit. To enable this feature, switch the pop-up menu below the box Menu Bar to the item Display loads for each single processing unit.

If you use this alternative display mode, the option Mark secondary CPUs will be shown additionally. If you enable this option and your computer is working with different types of processors, these types will be visualized by using distinct shades of gray in the menu bar. Primary processors are shown in normal display mode, while secondary processors appear with a slightly gray marking. What is considered primary and secondary depends on the manufacturer of the respective CPU hardware:

• With Intel chips, physical processor cores are regarded as primary, logical processor cores as secondary. A logical processor core is present if the Intel processor supports the feature Simultaneous Multithreading (Intel Hyper-Threading Technology) and this processor is simulated by executing commands as a second thread on a real processor core.

• With Apple Silicon, performance cores are considered primary, efficiency cores as secondary. The performance cores execute commands with maximum power, while efficiency cores only consume a tenth of the energy.

Another option is related to the automatic zooming of all history graphs. This also applies to any graphs that may be activated within the menu items (see next section). Normally, System Monitor magnifies the display of the curves so that the scale corresponds to the range of values that has been observed so far. That way, even small peaks become visible. However, when a history graph is placed next to a bar graph, this technique can result in visual differences that can be misleading: 100% load in the bar graph does not necessarily correspond to 100% in the history graph if this maximum load has not occurred yet. If this behavior is not desired, you can switch it off by unchecking Magnify all history graphs to actually observed value ranges.

Processors: Menu Items

At least the following items will be shown as part of the menu associated with this monitor section:

• User: the total load on all processors which is caused by processing within user applications.
• System: the total load on all processors which is caused by processing within operating system functions.
• Reduced: the total load on all processors which is caused by processes running with reduced priority.
• Idle: the total percentage where the processors have been idle.
• Processes: the number of processes currently running in the system. This includes your own applications, the applications of other users, and the services of the operating system.
• Active since: the uptime passed since the operating system had been started.

The reading Reduced is also known by the term nice in computer jargon. A process that runs with reduced priority behaves “nicely” and modest in respect to the remainder of the system. It will only occupy the processors when nothing else has to be done.

You can also include the following items in addition:

Show GPU loads for supported graphics chips: This option allows you to also include the current load of supported Graphics Processing Units (GPUs) in the menu. In everyday language, GPUs are called “graphics chips” or “graphics cards”. They mainly compute the current images and 3D sceneries shown by your computer on screen, but can also be used to help the main processor cores, in particular by offloading jobs with vector and matrix operations, machine learning, or Neural Engine processing. Setting a check mark causes a GPU section to be added to the menu that lists all supported graphics processors by name. It is not possible to influence the sort order in which multiple GPUs are shown.

The values for GPU utilization are provided by the drivers of the respective chips, and there is no standardized way to do that. For this reason, this feature may not work correctly or not at all for specific graphics chips. System Monitor cannot influence this.

Show top 5 processor consuming processes: When setting a check mark here, System Monitor additionally collects information which currently running processes are responsible for the major part of the load. The process names will be listed in one section of the menu, sorted by their contributions to the total load. The corresponding percentages will be listed as well.

Apple does not permit that this feature is distributed via the App Store. The function will become selectable when you activate our free add-on application System Monitor Plus which can be downloaded outside the App Store.

Retrieving the process list is a costly operation for technical reasons. The load caused by System Monitor itself will slightly increase when you enable this feature. If System Monitor detects that system load is excessively high, it will automatically pause the top 5 feature for at least one minute. In that case, a notice will appear instead of the top 5 processes in the list and the respective setting will be disabled temporarily.

To show the full list of processes, you can open Apple’s Activity Monitor application. Select the item Launch Activity Monitor in the menu.

Additional load graphs: In addition to the total load value in the menu bar, you can also insert further history graphs into the menu, showing the detail load on each processor for the last 30 seconds graphically. You only need to check the respective processors in the table. By pressing the buttons All or None, you can automatically add all processors, or remove them, respectively.

System Monitor sees the processors from the same standpoint as the operating system; it does not use the point of view of the hardware. A processor is a processing unit administered by macOS, no matter if it is located on an individual chip, or only as a processor core within a chip. Some processors use special technology to emulate more processing units than actually available.