BUG: kworker hangs the GPU on drm and i915 since 3.8.x under X11

[Daniel Vetter]

On Sat, Apr 6, 2013 at 6:24 PM, George Amanakis <g_amanakis at yahoo.com> wrote:
> Indeed, I set explicitly drm_kms_helper.poll=0 since 2.35.x. See here:
> http://souriguha.wordpress.com/2011/03/08/how-to-solve-problem-with-thinkpadkslowd-kworker-on-linux-kernel-2-35-2-36/
>
> Mouse and keyboard freezes intermittently some time after boot up. Actually
> the problem has to do with the GPU lagging and displaying the changes later.
> This results in an almost unusable desktop environment. Top will report the
> high CPU usage by 3-4 processes named kworker. With the
> drm_kms_helper.poll=0 it was until the 3.8.x kernel resolved.
>
> Since the 3.8.x kernels the exact same problem appeared again. The problem
> persists with the latest 3.9-rc5 too.

Ah, so it seems to be a plain hpd irq storm (since you have massive
cpu loads), not edid readings taking forever (which would still cause
the mouse to lag horribly on 3.8 and earlier, but without cpu load).
The edid reading issues should be fixed in 3.9. For hpd irq storms
Egbert Eich from Suse is working on some patches to mitigate this.
Infrastructure prep work is already merged for 3.10, hopefully we can
merge the actual mitigation logic, too.

I'll try no to forget to ping you once it's merged, so that you can
test it a bit.

Cheers, Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch