[ltp] glxgears on a T42 (Fedora Core 3) with ATI Mobility Radon 7500

[Noah Dain]

On 5/12/05, Marius Gedminas <mgedmin@b4net.lt> wrote:
> On Thu, May 12, 2005 at 11:50:21AM -0400, David A. Desrosiers wrote:
> > > BTW, on an old Thinkpad 600X running Fedora Core 3, etc., this
> > > phenomena does not occur.  Moreover, the gears visually turn very
> > > fast even though the frame rate is about 100 fps.
> >
> >       What you're seeing visually is the same effect that spinning
> > rims on a car at certain speeds will exhibit.. it will almost look as
> > though the wheels are spinning backwards slowly, or rotating much
> > slower forwards than is actually happening.
> >
> >       The gears are spinning fast, but they appear to be moving
> > slowly on your screen because it executes a full rotation before the
> > screen refreshes to show it.
>=20
> Many full rotations, actually -- laptop LCD screens update at 60 fps,
> while glxgears pumps out hundreds of fps.
>=20
> >       When you cover the glxgears window partially with a terminal
> > window, you're simply "shunting" some of that drawing output, so what
> > remains can rotate faster. Its the same thing if you resize that
> > window to be smaller or larger.
>=20
> Another thing -- if you use some sort of dynamic clock scaling daemon
> (e.g. powernowd), whenever you move a window around, the CPU usage
> momentarily grows, and the daemon bumps up the CPU speed, and that in
> turn causes glxgears to get a higher frame rate.
>=20
> >       Its doing exactly what it should be doing.
> >
> >       One thing you can try is backing the bpp down to 16, and using
> > the proper ATI or X.org 3D/GL drivers for your r300 chipset, instead
> > of the built-in driver that Fedora provides.
>=20
> I believe ATI Mobility Radon 7500 is RV250, which is fully supported by
> the open-source 3D driver that comes with X.org.
>=20
> Marius Gedminas
> --
> MCSE =3D=3D Marginal Computer Software Enthusiast
>=20
>=20
> BodyID:43692448.2.n.logpart (stored separately)
>=20
>=20
ATI's binary drivers do not support the 7500.  It's not actually a
Radeon core, it's the predecessor to it, but little details like this
never seem to bother marketing types.

and yes, xorg 6.8.2 supports it quite well, with agp 4x and dynamic
clock scaling of the 7500 chip (both xorg.conf options).

--=20
Noah Dain
noahdain@gmail.com