XO-1.75 relative performance

[Peter Robinson]

On Sun, Nov 6, 2011 at 4:51 PM, Jon Nettleton <jon.nettleton at gmail.com> wrote:
>> Hi Jon,
>>
>> We are doing some forwards-planing with regards to the XO-1.75. Would
>> you be able to tell us what kind of performance we can expect from the
>> graphics driver that you are working on? Would it support 3D hardware
>> acceleration?
>
> Well yes and no.  The graphics hardware does support 3d acceleration,
> however currently that is only supported via a binary driver.  We also
> don't have all the documentation nor man power to write a 3d driver.
> The nouveau team has had 3 to 4 people working full time on a driver
> for almost 4 years and their driver is just getting to a stable usage
> point for desktop compositing.

nouveau has been very usable for quite some time. I was using it
without issues back in F-12/13 timeframe without too many issues.

> For a general idea of performance our 3d graphics hardware will run
> Quake3 at native 1200x900 resolution with medium quality graphics at
> about 30fps on average.
>
>>
>> We are considering working to get GNOME 3 running, but for that to
>> work well we'll need some good graphics capabilities.
>
> There should be a distinction between GNOME 3 and gnome-shell.
> Gnome-shell is the only part of GNOME 3 that requires 3D acceleration.
>  Could our hardware run gnome-shell?  Well that would take a bit of
> time to figure out.  To my knowledge nobody has shown gnome-shell
> running with clutter utilizing the OpenGLES backend.  Last I remember
> clutter didn't support texture from pixmap capabilities with their EGL
> backend, so that may still have to be implemented.  This may have
> changed in the last couple of months by I have definitely not seen it
> demonstrated or talked about anywhere.

That's not exactly entirely true. There's a number of other apps that
are making using of clutter through clutter-gtk, clutter-gst or MX.
totem is one of these for example. Also before long gnome is planning
on deprecating non gnome-shell based UXs and concentrating on getting
sofware rendering up to a reasonable speed. We can start testing this
in F-17 as it'll be a feature [1]. Phoronix has more details on
llvmpipe [2] and the gallium3D bits [3]

> The bigger concern I have with targeting a compositing window manager
> is the amount of RAM that it needs.  Every window also has a
> duplicated texture in memory that is used to create the composited
> display.  Generally gnome-shell will use 100+MB's of RAM just to
> display the desktop, and there is no way to tweak around this by using
> 16-bit colors as everything is an ARGB texture.  On a machine with 1GB
> of RAM this isn't so bad, but that is a hefty chunk of memory for a
> machine with 512MB's of memory.  Oh and that is just system RAM it
> doesn't take into account the memory that is needed for the actual
> graphics engine.

Aren't the production 1.75s moving to 1Gb of RAM due to pricing of the
different units?

> To sum things up.  Yes the hardware should have the capabilities to
> run gnome-shell, again I say should as it is very untested.  I would
> not recommend targetting it's use in any future plans unless you have
> GNOME and Xorg hackers lined up to spend a good chunk of time working
> on it.

Peter

[1] https://fedoraproject.org/wiki/Features/Gnome_shell_software_rendering
[2] http://www.phoronix.com/scan.php?page=news_item&px=MTAxMTI
[3] http://www.phoronix.com/scan.php?page=news_item&px=MTAwNTg