On Sun, Aug 15, 2010 at 9:06 PM, Andy Lutomirski luto@myrealbox.com wrote:
You might be hitting the infamous hotplug storm [1]. The symptoms vary by kernel version.
Hmm. I don't think it's a storm. The drm.debug=4 thing shows things just every 10 seconds. That seems pretty controlled.
Of course, it seems to be several milliseconds worth of work then, so it's not _too_ controlled. I must be missing some detail.
If I'm right, the outputs of intel_bios_dumper and intel_bios_reader could be instructive (both are in intel-gpu-tools).
My version of intel-gpu-tools must be old (fedora 12). It has intel_gpu_dump and intel_reg_write and some other apps, but not the bios-dumper/reader.
Not that I could read the output of them anyway, I bet ;)
You could also try intel_reg_write 0x61110 0x0 and see if the problem stops (at least until a suspend/resume cycle). That command turns off output hotplug on the card, which has the side effect that the kernel will stop acting on bogus interrupts.
# intel_reg_write 0x61110 0x0 Value before: 0x4000220 Value after: 0x0
but it doesn't seem to change any behavior. Still that sdvo probe every 10 s, and still 1% of CPU for kworker in top. But that kworker thing definitely has to be separate from the 10-second sdvo probe, because it shows up all the time (ie top updates every second).
But right now the wife is using that machine, so I can't check the "it should be totally idle, what the heck is going on" behavior at the moment.
Linus
Linus