The Power Overview Window

To open the Power Overview window, select the menu item Window > Show Power Overview or press the key combination ⌘ + 1. The window will also open automatically at startup if you have closed all other result windows.

This window has a different structure, depending on whether you are using a Mac with Intel processor or with Apple processor. The two variants will be described below.

Power overview (for Intel-based Macs)

The window is divided into three parts:

• Power data for the processor chip
• Main memory usage and input/output bandwidths
• Power history of the processor chip with indication of the temperature level

The heading of the top box is the exact designation of the Intel processor. The nominal clock frequency is also listed, as well as the number of threads (logical processors), the number of built-in processor cores and the distribution of cores onto chip packages. The box contains the following values:

• Processor average frequency: the effective clock frequency that can be attributed to the processor, both as a percentage and as an absolute value in relation to the nominal clock speed. The effective frequency takes into account a possible change of processor clock speed during measurement, as well as entering sleep mode during the measurement second, which is to be regarded as a zero value.
• CPU cores active: The proportion of time in which at least one CPU core was active and switched on during measurement.
• Integrated GPU active: The proportion of time in which at least one core of the integrated GPU was active and switched on during measurement.
• CPU/GPU overlap: The proportion of time in which CPU and GPU were active at the same time.
• Average number of active cores: The average number of CPU cores that were active during measurement.

The second box indicates the use of main memory (RAM) for currently running processes and provides an overview of the input/output areas of a computer in classic data processing, namely the read/write operations across all disk-like storage devices (hard drives, SSDs, memory cards, etc.), as well as all network connections (Ethernet, WiFi, etc.) Indicated are:

• RAM Usage: the main memory used for processes and operating system kernel in relation to the installed amount of RAM. This omits the part of memory used for disk and network cache.
• Swap: the amount of memory currently swapped to disk. If the computer has enough RAM so that no swapping occurred since the last start of the operating system, “no swap” will be shown.
• App: a value defined by Apple that indicates how much RAM is currently being used by running applications. This is memory allowed to fully participate in swapping operations.
• Rsv: reserved memory, which means that swap operations are not permitted. This applies, for example, to the innermost parts of the operating system kernel, in particular to the components that must control swapping.
• Cmpr: additional memory, which would actually have to be swapped out, but whose contents have been compressed instead and are still hold in RAM.
• Cache: memory in use as disk and network cache.
• CPU not in “Last Level Cache flushed” idle state: The amount of time during measurement in which the CPU cores could not enter an energy saving sleep mode on such a low level that all CPU internal caches would have to be transferred to RAM.
• Disk R: Data transfer rate of read operations for all disk-like storage devices, in megabytes per second
• Disk W: Data transfer rate of write operations for all disk-like storage devices, in megabytes per second
• Network R: Data transfer rate of read operations (reception) from all network ports, in megabytes per second
• Network W: Data transfer rate of write operations (send) to all network ports, in megabytes per second

The bottom box shows the power consumption of the Intel processor as well as the temperature condition during the measurement:

• Package power: Power consumption of the entire chip in watts.
• avg: Average value for power consumption during the runtime of the program.
• peak: Peak value for power consumption during the runtime of the program.
• Thermal status: Classification of the temperature of the Intel chip by macOS in relation to specified operating temperature. The possible conditions are listed at the end of this chapter.
• a graph presenting the history of package power within the last 30 seconds. The latest values are on the right.

Power overview (for Macs with Apple Silicon)

The window is divided into three parts:

• Power data for the system-on-a-chip
• Main memory usage and bandwidths for different hardware sections
• Power history of CPU and GPU with indication of the temperature level

The heading of the top box is the exact designation of the Apple processor. This is followed by the distribution of the different types of cores:

• E: Number of efficiency cores with less computing power and low energy consumption
• P: Number of performance cores with normal computing power and higher energy consumption
• GPU: Number of cores of the graphics processor
• Clusters: Number of assemblies into which Apple logically divided the chip. For example, E and P cores are located in different sections of the chip.

The box contains an overview of the power distribution among the individual cores of the processor:

• Efficiency CPU cores: the amount of time in which the E-cores were employed during the measurement and the resulting effective clock frequency. The effective frequency takes into account a possible change of processor clock speed during measurement, as well as entering sleep mode during the measurement second, which is to be regarded as a zero value.
• Performance CPU cores: as before, but for the P cores of the processor
• GPU cores: as before, but for the graphics cores of the processor
• Apple Neural Engine: the power consumption of special processor units that are used for Machine Learning. A utilization or effective frequency cannot be specified here, as macOS does not collect such data.

The second box indicates the use of main memory (RAM) by currently running processes and provides an overview of the bandwidths that the Apple Silicon used during measurement for certain subtasks. Indicated are:

• RAM Usage: the main memory used for processes and operating system kernel in relation to the installed amount of RAM. This omits the part of memory used for disk and network cache.
• Swap: the amount of memory currently swapped to disk. If the computer has enough RAM so that no swapping occurred since the last start of the operating system, “no swap” will be shown.
• App: a value defined by Apple that indicates how much RAM is currently being used by running applications. This is memory allowed to fully participate in swapping operations.
• Rsv: reserved memory, which means that swap operations are not permitted. This applies, for example, to the innermost parts of the operating system kernel, in particular to the components that must control swapping.
• Cmpr: additional memory, which would actually have to be swapped out, but whose contents have been compressed instead and are still hold in RAM.
• Cache: memory in use as disk and network cache

The bottom box shows the power consumption of the Apple chip as well as the temperature condition during the measurement:

• Thermal status: Classification of the temperature of the Apple chip by macOS in relation to specified operating temperature. The possible conditions are listed in the next section.
• the corresponding power values, divided into CPU and GPU, as well as their history within the last 30 seconds. The latest values are on the right.

Temperature conditions defined by macOS

The operating system internally defines different temperature levels that indicate whether the current operating temperature of the processor is critical in relation to the maximum permissible temperature. The information does not correspond to a specific absolute temperature value, but indicates whether macOS must take countermeasures to keep the processor within the specified thermal range. Countermeasures include temporarily switching off certain processes (software) or processor cores (hardware) at very short time intervals, which leads to a reduction in power consumption by throttling. The following terms are used, which should be self-explanatory:

• nominal
• slightly elevated
• moderately elevated
• heavily elevated
• sleeping
• trapping

Trapping means that the hardware is triggering internal temperature alarms.

Resetting history data of the currently running session

The Power Overview window indicates several readings which depend on the history of the running application session. This includes, for example, the power graphs and their average and peak values.

If you test different applications or different power profile settings on your Mac, it can be helpful to reset these statistics to get “fresh” values for a new test run. You can do this without restarting the program by choosing the menu item Commands > Clear History of Power Overview.