[extropy-chat] SECOND LIFE not working
robert.bradbury at gmail.com
Mon Dec 11 13:36:45 UTC 2006
On 12/11/06, Eugen Leitl <eugen at leitl.org> wrote:
> This hardware should run great. Which graphics accelerator card do
> you have?
A better question might be whether you have glxgears and can run it? Its a
very useful benchmarking tool to get a feel for what the hardware + software
can do. And it isn't as simple as "what the hardware can do" as its a
combination of the hardware and software combined. There are at least four
levels of this:
a) What will the hardware do?
b) What will the operating system drivers do?
c) What will the user mode graphics drivers do? (esp. do they support
"Direct Rendering" (DRI))
d) What does the application program (e.g. Second Life) do?
Glxgears tests a+b+c. If it isn't on your naive O.S. you can test it by
booting up one of the Linux LiveCDs which is supposed to support Xorg
7.0and the latest release of OpenGL (and the fancy rotating cube
Xgl or Aiglx).  If you can get glxgears to run at 800 FPS or above you
probably have "direct rendering" which lets the user mode graphics drivers
get relatively direct control over the hardware and push on it.
Alternatively if the fancy cube rotates fast, the fancy window effects are
slick, etc. then you probably have a VR capable system. If not, then as
Eugen points out you need a graphics card upgrade. If you know what to buy
you can probably get a gamers 2nd hand discard on eBay relatively cheap.
The hardware I've got (a) is fairly decent. Once one gets (b+c) right you
can get 800-850 FPS in glxgears. I've seen it as high as 1200 using some
older drivers that don't support the latest variants of (c). I would
suspect that Eugen and some others are probably in the 1500 to 2500 range
(I'd be curious to know).
You should be getting 25 fps with that hardware without breaking a sweat.
> seems to indicate there are some light performance problems, but nowhere
> as bad as the 3 fps you've cited.
It is worth noting that the machines I've seen SL run on are mid -range
2.3-2.8 GHz Pentium 4s. And that the FPS numbers I cite above are for the
"standard" glxgears window size (which is perhaps 1/8 of a 15" screen
size). If resized to almost a full 15" screen it slows down to ~180 FPS.
If one doesn't have (b+c) using DRI as outlined above then the standard
glxgears slows down to ~400-500 FPS *and* drives the main CPU to 100%
utilization. If you do anything else on the machine that uses the main CPU
(as would be the case in SL) the FPS numbers go through the floor.
The question for Randall really is *what* is the graphics hardware in the
machine? The G5 isn't what talks to the display. On Eugen's machine its
and add-in graphics card. On the machines I was discussing it is the Intel
"Northbridge" chip on the motherboard that has the integrated graphics
controller than handles the display. I suspect the same is true for
Randall's machine. Most of the more recent systems (< 3 y.o.) can handle it
*if* the software can.
1. It is important to run "glxinfo" before running "glxgears" to see if you
have "direct rendering" vs. "indirect rendering" (hardware vs. software).
Your hardware might support direct rendering but if the software isn't setup
to take advantage of it you are screwed.
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