Thunderbolt, Apple Monitor & MBA, and excess kworker load

[Dominik Brodowski]

Hi,

At work, I wish to attach a 27" Apple Display using thunderbolt to my Mac
Book Air 4,2 13". Using OS X, it works fine, but as I prefer using Linux, I
tested out Ubuntu's stock kernel and (among other) 3.5.0-rc3+ as of f40759e.
Hotplug doesn't work (known issue), but also with coldplug the display
reacts _very_ slow, way too slow for real use: The screen updates only every
half second or so. Is this a known bug? Might something go afoul with
kworker -- they need about 75% of the CPU with the large display attached,
and less than 1% _without_ the large display.

Any hints are most welcome, also on where I may dig further to determine the
root causes...

Thanks & best,

	Dominik