Date: Fri, 23 Jun 2006 10:28:39 -0700 From: Eric Anholt <eric@anholt.net> To: Mikhail Teterin <mi+kde@aldan.algebra.com> Cc: x11@freebsd.org Subject: Re: gears vs. glxgears; i915 for Linux binaries? Message-ID: <1151083719.18920.5.camel@leguin> In-Reply-To: <200606231317.21964@aldan> References: <200606231317.21964@aldan>
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On Fri, 2006-06-23 at 13:17 -0400, Mikhail Teterin wrote:
> First of all, allow me to thank you for the working DRI on my laptop with=
i915=20
> chipset. Although none of my Radeon desktops work yet, this is very welco=
me=20
> progress.
>=20
> After installing the linux_dri port, I wanted to compare the simple (glx)=
gears=20
> results between the Linux and the native binaries.
>=20
> The /compat/linux/usr/X11R6/bin/gears appears to be the same beast, as th=
e=20
> ${X11BASE]/bin/glxgears installed by the native Xorg port.
>=20
> Running the Linux gears seemed VERY fast -- they were spinning like crazy=
but=20
> the program reports just 1800 frames per 5 seconds -- around 380 FPS (all=
for=20
> the default small window).
>=20
> Running the native glxgears appeared much slower, but the reported stats =
were=20
> ~2.5 times higher -- around 950 FPS.
>=20
> Now, the reported speed difference is, likely, due to the fact, that the=20
> linux_dri does not (yet?) install the i915_dri.so, so no DRI is (yet?)=20
> possible for Linux programs on my laptop. But why does it *appear* to be=20
> faster?
The gears move at a constant rate of change per frame. You're blitting
frames to the screen faster than the screen outputs them. So, you get
some subset of the frames gears drew, which don't necessarily give you
the animation you expect. Sometimes the gears will even appear to go
backwards (just like hubcaps on a car in movies will sometimes).
I think glxgears is dumb for not syncing to vblank, and I run most of my
apps with syncing to vblank on. You can use driconf to set this.
You're getting software rendering with linux_dri. LIBGL_DEBUG=3Dverbose
is the way to debug DRI issues, but I can shortcut here and yes, the
absence of i915_dri.so is the problem. We need to get linux_dri updated
to a set of recent Mesa binaries. I wonder what our current
linux_base's package of dri modules looks like?
--=20
Eric Anholt anholt@FreeBSD.org
eric@anholt.net eric.anholt@intel.com
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