discrete graphics and you

In 2010 Apple introduced a feature in MacBooks with the aim of extending battery life “Automatic graphics switching” that switches between using either the integrated Intel GPU  inside the CPU or the standalone discrete AMD/Nvidia GPU.

The exact conditions however that make it switch one or the other were never clearly stated by Apple, and there has been much debate confusion and speculation on the subject.

Upon testing i found the answer to be pretty straight forward in that if a application ever loads the OpenGL.framework the machine switches to the standalone GPU (easiest way to determine this is inspect the files area of the program with Activity Monitor and look for OpenGL.framework) ,i have so far unable to find any other framework besides it to trigger the switch.

Determining what can make it load that framework is not that straight forward however, and remember it does not have to be linked for it to be loaded, any API that relies on it can trigger it’s loading, and the likely culprit in most cases will be Core Animation which uses OpenGL backing.

So to make sure you do not trigger the standalone GPU you need to make sure your code does not rely on any Core Animation API’s or any that otherwise uses OpenGL, also remember that all the “Effects” in Interface Builder require a Core Animation layer that will trigger the loading of the OpenGL.framework

EDIT: As of lion there is a property you can control this behavior with, the NSSupportsAutomaticGraphicsSwitching key as detailed in the Allowing OpenGL applications to utilize the integrated GPU QA

 

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s