DisplayLink Software - High CPU on MBA

rich2019 · 07-30-2019, 11:15 AM

This is repeatable on my MacBook Pro 2012 using Mac Screen Sharing to VNC to another machine. If the other machine is doing frequent updates (eg like some redrawing of part of a webpage, a very common occurence), then the CPU will go insane on my Mac.

I have looked at Activity Monitor to see that, in this order, the following are consuming CPU:
a. WindowServer (insanely active)
b. DisplayLinkManager (insanely active)
c. Screen Sharing (insanely active)
d. kernel_task
e. DisplayLinkUserAgent (not very busy)

DisplayLinkManager and Screen Sharing are hogging about the same amount of CPU.

I tried running Quartz Debug to see when screen updates were occurring but this irritatingly doesn't work over DisplayLink, so I have no idea whether the Screen Sharing is refreshing its view far too often (I am using adaptive quality, not full), causing DisplayLinkManager to try and push these updates through to the WindowServer, causing a global system slow down.

I also tried running Instruments and looking at DisplayLinkManager. Nothing of note comes up in that other than some secondary thread is very very busy, but as it is not a debug build I cannot see what it is actually doing.

Your developers will be able to repeat this very easily by doing the above!!! It seems that the entire screen is being polled to be pushed out to the external DisplayLink hardware, without any form of acceleration.

Is there any fix for this? I have recently bought this DisplayLink device and am quite disappointed by the CPU hogging that is occurring.

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07-30-2019, 11:15 AM	#11
rich2019 Junior Member Join Date: Jul 2019 Posts: 1	This is repeatable on my MacBook Pro 2012 using Mac Screen Sharing to VNC to another machine. If the other machine is doing frequent updates (eg like some redrawing of part of a webpage, a very common occurence), then the CPU will go insane on my Mac. I have looked at Activity Monitor to see that, in this order, the following are consuming CPU: a. WindowServer (insanely active) b. DisplayLinkManager (insanely active) c. Screen Sharing (insanely active) d. kernel_task e. DisplayLinkUserAgent (not very busy) DisplayLinkManager and Screen Sharing are hogging about the same amount of CPU. I tried running Quartz Debug to see when screen updates were occurring but this irritatingly doesn't work over DisplayLink, so I have no idea whether the Screen Sharing is refreshing its view far too often (I am using adaptive quality, not full), causing DisplayLinkManager to try and push these updates through to the WindowServer, causing a global system slow down. I also tried running Instruments and looking at DisplayLinkManager. Nothing of note comes up in that other than some secondary thread is very very busy, but as it is not a debug build I cannot see what it is actually doing. Your developers will be able to repeat this very easily by doing the above!!! It seems that the entire screen is being polled to be pushed out to the external DisplayLink hardware, without any form of acceleration. Is there any fix for this? I have recently bought this DisplayLink device and am quite disappointed by the CPU hogging that is occurring.