The driver is very slow with Kicad

[Alex Deucher]

On Mon, Nov 28, 2011 at 3:33 PM, Element Green
<element at elementsofsound.org> wrote:
> Hello,
> I happened upon this thread when searching for information on slow
> performance with Kicad and the open source radeon driver.
> http://lists.x.org/archives/xorg-driver-ati/2011-August/021077.html
> I have a ATI/AMD HD 5800 series video card in my laptop.  I've also been
> rather impressed with the open source driver, even compared to Catalyst
> (which seems to suffer from many problems, especially with gnome 3).  So I'm
> very keen on getting Kicad to be usable with it.
> After doing a lot of profiling with sysprof, oprofile and gprof, I
> discovered that the open source radeon driver works acceptably when the
> radeon Kernel module is not loaded.  I discovered this when I was trying to
> switch back to the open source driver from Catalyst and there was an issue
> with the Kernel module loading.
> From what I can tell from /var/log/Xorg.0.log there is some rather
> significant initialization differences when the radeon Kernel module has not
> been loaded.  I tried disabling dri and dri2 to see if they were the
> culprit, but that makes Xorg non functional (weird square block for a mouse
> cursor over a black or corrupted display).  I also tried disabling many
> other extensions and modules (Render, glx, Composite), but none of them
> seemed to be causing the issue.
> Does this lend any information in regards to what could be causing the poor
> performance with Kicad?  Any ideas what different code paths could be

When you don't load KMS, you disable acceleration so you are getting
software rendering.  Adding:
Option "NoAccel" "True"
to the device section of your xorg.conf should produce the same
effect.  IIRC, Kicad uses certain operations that are not accelerated
which causes a fallback to software rendering.  This ends up being
slower than pure sw rendering due to ping-ponging between GPU and CPU
memory and waiting for the gfx pipe to drain.

Alex

> responsible?  From a rough view from "top" I can see that the CPU usage is
> about 80% and 20% for Pcbnew and Xorg in the Catalyst and non Radeon kernel
> module load cases (good performance cases) and 20% and 80% for Pcbnew and
> Xorg in the normal radeon driver case (the poor performance case).  So it
> would seem that Xorg and friends are taking up more CPU (about 3 times as
> much) in the poor performance case.
> Best regards,
> Element Green
>
>
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