intel videocard performance degraded severely after 9.4 update

[Riccardo Mottola <riccardo.mottola%libero.it@localhost>]

Hi,

I updated my trusty R52 ThinkPad to 9.4 - i915.
All went quite well.

wifi is unreliable - but that is most probably the same isue I have on
the T30 and I am already investigating that with Martin.

X11 performance however is close to unusable, even a simple xterm has
issues scrolling and there are artifacts in redrawing, sometimes
garbage, something wrong colors in the title bar!
With 9.3 it wasn't a a gaming platform, but quite usable for terminal
and programming.
I think that console switch sometimes had it loose acceleration, but it
was never so bad and never had artifacts.

wscons look and perform fine, the issue is X11.

[     5.106546] kern.module.path=/stand/i386/9.4/modules
[     5.106546] kern info: [drm] Memory usable by graphics device = 128M
[     5.106546] kern info: [drm] Supports vblank timestamp caching Rev 2
(21.10.2013).
[     5.106546] kern info: [drm] Driver supports precise vblank
timestamp query.
[     5.106546] i915drmkms0: interrupting at irq 11 (i915drmkms0)
[     5.106546] WARNING: clock gained 4 days
[     5.126546] kern error:
[drm:(/usr/src/sys/external/bsd/drm2/dist/drm/i915/intel_fifo_underrun.c:363)intel_cpu_fifo_underrun_irq_handler]
*ERROR* CPU pipe A FIFO underrun
[     5.126546] kern error:
[drm:(/usr/src/sys/external/bsd/drm2/dist/drm/i915/intel_fifo_underrun.c:363)intel_cpu_fifo_underrun_irq_handler]
*ERROR* CPU pipe B FIFO underrun
[     5.136547] kern error:
[drm:(/usr/src/sys/external/bsd/drm2/dist/drm/i915/i915_gem_stolen.c:555)i915_pages_create_for_stolen]
*ERROR* failed to load DMA map for stolen object: -22
[     5.136547] kern info: [drm] initialized overlay support
[     5.176547] kern error:
[drm:(/usr/src/sys/external/bsd/drm2/dist/drm/i915/i915_gem_stolen.c:555)i915_pages_create_for_stolen]
*ERROR* failed to load DMA map for stolen object: -22
[     5.186566] intelfb0 at i915drmkms0
[     5.186566] intelfb0: framebuffer at 0xdc295000, size 1024x768,
depth 32, stride 4096
[     5.816557] wsdisplay0 at intelfb0 kbdmux 1: console (default, vt100
emulation), using wskbd0

these errors look a bit scary, but I am pretty sure  the fifo underrun
was there before.
However *ERROR* failed to load DMA map for stolen object: -22 is new.


In Xorg.0.log I see:
[  1561.785] (EE) intel(0): Failed to submit rendering commands (Invalid
argument), disabling acceleration.

that doesn't look promising!

Riccardo