On Sun, Aug 15, 2010 at 07:32:15PM -0700, Linus Torvalds wrote:
I started wondering why 'top' was showing an otherwise idle system as having a load average of 0.5+, and worker threads constantly using the CPU.
So I did a system-wide profile, and got the attached output (look at it in a really wide terminal).
There seems to be something _seriously_ wrong with i915 SDVO detect. This is on an Apple Mac Mini (hey, your favorite problem child!), and apparently it spends 20% of its non-idle CPU time just doing udelay's for the i2c SDVO connection detection.
That sounds a bit wrong, doesn't it?
I don't know how recent this is - it might have been going on for some time without me noticing. It's the wife's computer, and the same thing doesn't seem to happen on my Core i5 desktop
Any ideas? Any information I can give about the machine?
You're not alone. I'm seeing similar things on my machine (AMD,Radeon). The monitor outputs are polled every 10 sec in drivers/gpu/drm/drm_crtc_helper.c.
There is a patch attached to the following bug report that disables polling and solves the problem for me: http://bugs.freedesktop.org/show_bug.cgi?id=29536