Re: Minimum system requirements for GNOME Shell

[Emmanuele Bassi <ebassi gmail com>]

On Sat, 2010-12-25 at 10:19 +0100, Tomasz Torcz wrote:
> On Fri, Dec 24, 2010 at 11:30:08PM +0000, Emmanuele Bassi wrote:
> > 60+fps or 30 fps are utterly meaningless numbers.
> > 
> > the only number you really want to use is the vsync of your monitor:
> > anything more and you're just wasting power and resources.
> > 
> > also, you *really* don't want sustained updates: it's a user shell, not
> > quake.
> 
>   A propos, what about impact on other OpenGL application?  Compared
> to metacity compositing, Quake Live under gnome-shell experiences heavy
> performance hit (at lest with g-s version from Fedora 14).

yes, don't use that. you need master from Clutter, Mutter and GNOME
Shell to test performance, since a lot of work has gone into that
particular field in the past three months, and it hasn't yet been
packaged.

>   I will try to benchmark ioquake with metacity, g-s and compiz to provide
> hard numbers.

hard numbers are always good, but benchmarking a compositor is always
going to be tricky.

if the application is chugging frames faster than the compositor can
composite and paint them then you won't see much, and there's actually
the chance that the applications starts DoS-ing the compositor and ruin
the performance. ideally, you want all applications to be locked onto
the compositor framerate, and the compositor vblank-locked. work on how
to achieve that with the help of toolkits and compositors is under
way[1].

don't use metacity as a reference point, because the compositor is
completely different. use mutter with its default compositor plugin
(i.e. run "mutter --replace" instead of "gnome-shell --replace").

as far as our benchmark go, mutter's default plugin yields similar or
better numbers than compiz when using GLXgears - and although GLXgears
is *not* a benchmark, it's basically what everyone uses a reference
point.

ciao,
 Emmanuele.

[1] http://dri.freedesktop.org/wiki/CompositeSwap

-- 
W: http://www.emmanuelebassi.name
B: http://blogs.gnome.org/ebassi