On Sunday 05 November 2000 19:23, Guillaume Cottenceau wrote:
| Vadim Plessky <[EMAIL PROTECTED]> writes:
| >
| > Do you mean gcc doesn't use 3DNow! instruction set?
|
| It does -- but do you really know the purpose of these instructions? (and
| the fact that the penalty is high while using the coprocessor at the same
| moment).
Yes, I know what they are for.
But I want to add that they are classical example of SIMD architecture (by
von Neiman computer architecture classification)
So, they can have much wider use then just "Multimedia"
As many people, even developers, don't know what is SIMD, Intel created
marketing flavour called MMX around these instructions. Same blah-blah-blah
like MS did around many Windows functions.
| It's highly unprobable that any app could be "vastly" optimized using
| 3dnow. Same story with MMX!
Depends on compiler. Despite the fact that utlra-modern CPUs now on a market,
compilers do not develop so fast. The best is to have MMX(or 3Dnow) optimized
library, and link against it when compiling. Of course, it can be shared
library. GCC site is so limited that I don't know what to think about Athlon
support in gcc. No info on it...
| It only works noticeably for very specific things, and the only one I am
| aware of is MPEG uncompression. Fortunately kde supports MMX for its mpeg
| routines for example.
|
It should work also for image manipulations and audio
compression/decompression/mixing/editing.
In PC/Windows world, Adobe Photoshop uses MMX heavily.
Also, DirectX supports MMX (and 3DNow!)
| So, you can recompile the app you'll like to see quicker for your specific
| arch, but we'll not do that.
|
As there is no something like DirectX and Direct3D on Linux, it's rather
difficult to separate these layers.
May be, some parts of X-Windows still can be classified as something similar
to DirectX. I this case, they should use MMX.
By the way, Sun also has set of similar instructions in UltraSPARC.
| >
| > Finally Mesa3D will benefit, for sure. I have seen mail from somebody on
| > one of the lists claiming he got +5FPS for software-only Mesa after
| > recompiling.
|
| Mesa, if used in software, will never be quick enough to be useable, due
| to its general-purpose design. At least things like "gears" will have
| framerate, but chromium or quake3, never.
I have ATI Mach 64 (Rage Mobility in notebook)
For some reason, 3D acceleration in it is not supported by XFree.
I really wonder how Linux can achieve significant market share if such
standard hardware/feature is not supported. (ATI is the leader in 3D chips
sales)
Anyway, I agree with you that Hardware is Better then Software...
| Used with hardware acceleration, 3dnow/mmx is nearly nothing because it
| competes with the hw accel which is ofcourse much quicker.
What about triangle processing in rendering pipeline? (first stage of
rendering process)?
I know, for example, NVidia uses 3DNow instruction set in its reference
driver (of course, for AMD processors). Asus driver for NVidia has
optimizations for 3DNow.
So, do not underestimate 3DNow, please...
--
Vadim Plessky
http://kde2.newmail.ru (English)
http://kde2.newmail.ru/index_rus.html (Russian)
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