#HARDWARE MONITOR OS X MANUALS#
#HARDWARE MONITOR OS X SOFTWARE#
#HARDWARE MONITOR OS X CODE#

Since top is open-source, we can investigate an actual formula/code for how this number is calculated, and the blog post summarizes this as: |elapsed_us| is the length of the sample period Every indication is that the two are computed identically on this machine. In every case, Activity Monitor’s “Energy Impact” was the same as top's POWER measure. I found the following blog post which investigates this calculation in much more detail: The number appears to be coming from the program top.

#HARDWARE MONITOR OS X SOFTWARE#

There are many aspects of power management, and they are a combination of very accurate measurement and software designs to reduce the power consumption. Since the CPU control's activity including RAM management and disk read/writes,Network Card and others for example improving RAM management also reduces power consumption that occurs by to frequent disk R/W activity. To see more information on above charts visit this article. Using the above information on per Application and the resulting cumulative Power usage Apple has implemented the Timer Coalescing and the App Nap features to manage Power consumption resulting in the Chart below. In summary, using the ms power measurement one is able to better control the overall power consumption. Here is a article from Apple about power management/consumption that goes in to bit more details how is power managed. The sampling rate is Milliseconds and the power is in Watts, and it measures the Total Power for the CPU while the Activity monitor breaks it down by Application/Process. The Power usage and the Temperature are products of the Frequency (the speed), or the amount of data processed. It displays the Power the Frequency and the Temp. It all starts with precision monitoring and measurements down to Milliseconds.Īs example Intel has made a tool to monitor the Intel CPU parameters.

A likely accounting method would assign to your application all of the energy use needed by the resources your application uses exclusively (say a custom USB device, access to an otherwise powered-down audio syste), and do some sort of pro-rating for shared hardware. Use of other resources, such as the audio system, doing disk I/O or using USB devices may be also factored in. A badly behaving app can have a much bigger impact on Haswell than on an 'old' Core 2 machine. This will highly vary between architectures.

#HARDWARE MONITOR OS X MANUALS#

You'd probably gain most insight by following Intel manuals first to understand the power states and energy management.

#HARDWARE MONITOR OS X CODE#

The latter can have much bigger effect.Īn application that needs to wake up exactly every 10ms to execute just a few lines of simple Obj-C code can have an order of magnitude larger energy impact than the same application executing thousands of lines of code but just once a second and not being very particular about exactly when within that second will the calculation happen.Īpple probably uses Intel's performance counters and accounts them to your application. It's not merely how much CPU does an application consume, but also how often and how flexible it is about it. There are many aspects of CPU utilization that affect energy consumption.

Hardware monitor os x