A
AirRaid
Larrabee's Rasterisation Focus Confirmed
Wednesday 23rd April 2008, 08:33:00 PM, written by TeamB3D
For many months, researchers and marketing fanatics at Intel have been
heralding the upcoming 'raytracing revolution', claiming rasterisation
has run out of steam. So it is refreshing to hear someone actually
working on Larrabee flatly denying that raytracing will be the chip's
main focus.
Tom Forsyth is currently a software engineer working for Intel on
Larrabee. He previously worked at Rad Game Tools on Pixomatic (a
software rasterizer) and Granny3D, as well as Microprose, 3Dlabs, and
most notably Muckyfoot Productions (RIP). He is well respected
throughout the industry for the high quality insight on graphics
programming techniques he posts on his blog. Last Friday, though, his
post's subject was quite different:
"I've been trying to keep quiet, but I need to get one thing very
clear. Larrabee is going to render DirectX and OpenGL games through
rasterisation, not through raytracing.
I'm not sure how the message got so muddled. I think in our quest to
just keep our heads down and get on with it, we've possibly been a bit
too quiet. So some comments about exciting new rendering tech got
misinterpreted as our one and only plan. [...] That has been the goal
for the Larrabee team from day one, and it continues to be the primary
focus of the hardware and software teams. [...]
There's no doubt Larrabee is going to be the world's most awesome
raytracer. It's going to be the world's most awesome chip at a lot of
heavy computing tasks - that's the joy of total programmability
combined with serious number-crunching power. But that is cool stuff
for those that want to play with wacky tech. We're not assuming
everybody in the world will do this, we're not forcing anyone to do
so, and we certainly can't just do it behind their backs and expect
things to work - that would be absurd."
So, what does this mean actually mean for Larrabee, both technically
and strategically? Look at it this way: Larrabee is a DX11 GPU with a
design team that took both raytracing and GPGPU into consideration
from the very start, while not forgetting performance in DX10+-class
games that assume a rasteriser would be the most important factor
determining the architecture's mainstream success or failure.
There's a reason for our choice of phrasing: the exact same sentence
would be just as accurate for NVIDIA and AMD's architectures. Case in
point: NVIDIA's Analyst Day 2008 had a huge amount of the time
dedicated to GPGPU, and they clearly indicated their dedication to non-
rasterised rendering in the 2009-2010 timeframe. We suspect the same
is true for AMD.
The frequent implicit assumption that DX11 GPUs will basically be DX10
GPUs with a couple of quick changes and exposed tesselation is weak.
Even if the programming model itself wasn't significantly changing (it
is, with the IHVs providing significant input into direction), all
current indications are that the architectures themselves will be
significantly different compared to current offerings regardless, as
the IHVs tackle the problem in front of them in the best way they know
how, as they've always done.
The industry gains new ideas and thinking, and algorithms and
innovation on the software side mean target workloads change; there's
nothing magical about reinventing yourself every couple of years.
That's the way the industry has always worked, and those which have
failed to do so are long gone.
Intel is certainly coming up with an unusual architecture with
Larrabee by exploiting the x86 instruction set for MIMD processing on
the same core as the SIMD vector unit. And trying to achieve leading
performance with barely any fixed-function unit is certainly
ambitious.
But fundamentally, the design principles and goals really aren't that
different from those of the chips it will be competing with. It will
likely be slightly more flexible than the NVIDIA and AMD alternatives,
let alone by making approaches such as logarithmic rasterisation
acceleration possible, but it should be clearly understood that the
differences may in fact not be quite as substantial as many are
currently predicting.
The point is that it's not about rasterisation versus raytracing, or
even x86 versus proprietary ISAs. It never was in the first place.
The raytracing focus of early messaging was merely a distraction for
the curious, so Intel could make some noise. Direct3D is the
juggernaut, not the hardware.
"First, graphics that we have all come to know and love today, I have
news for you. It's coming to an end. Our multi-decade old 3D graphics
rendering architecture that's based on a rasterization approach is no
longer scalable and suitable for the demands of the future." That's
why the message got so muddled, Tom. And no offence, Pat, but history
will prove you quite wrong.
http://www.beyond3d.com/content/news/631
Wednesday 23rd April 2008, 08:33:00 PM, written by TeamB3D
For many months, researchers and marketing fanatics at Intel have been
heralding the upcoming 'raytracing revolution', claiming rasterisation
has run out of steam. So it is refreshing to hear someone actually
working on Larrabee flatly denying that raytracing will be the chip's
main focus.
Tom Forsyth is currently a software engineer working for Intel on
Larrabee. He previously worked at Rad Game Tools on Pixomatic (a
software rasterizer) and Granny3D, as well as Microprose, 3Dlabs, and
most notably Muckyfoot Productions (RIP). He is well respected
throughout the industry for the high quality insight on graphics
programming techniques he posts on his blog. Last Friday, though, his
post's subject was quite different:
"I've been trying to keep quiet, but I need to get one thing very
clear. Larrabee is going to render DirectX and OpenGL games through
rasterisation, not through raytracing.
I'm not sure how the message got so muddled. I think in our quest to
just keep our heads down and get on with it, we've possibly been a bit
too quiet. So some comments about exciting new rendering tech got
misinterpreted as our one and only plan. [...] That has been the goal
for the Larrabee team from day one, and it continues to be the primary
focus of the hardware and software teams. [...]
There's no doubt Larrabee is going to be the world's most awesome
raytracer. It's going to be the world's most awesome chip at a lot of
heavy computing tasks - that's the joy of total programmability
combined with serious number-crunching power. But that is cool stuff
for those that want to play with wacky tech. We're not assuming
everybody in the world will do this, we're not forcing anyone to do
so, and we certainly can't just do it behind their backs and expect
things to work - that would be absurd."
So, what does this mean actually mean for Larrabee, both technically
and strategically? Look at it this way: Larrabee is a DX11 GPU with a
design team that took both raytracing and GPGPU into consideration
from the very start, while not forgetting performance in DX10+-class
games that assume a rasteriser would be the most important factor
determining the architecture's mainstream success or failure.
There's a reason for our choice of phrasing: the exact same sentence
would be just as accurate for NVIDIA and AMD's architectures. Case in
point: NVIDIA's Analyst Day 2008 had a huge amount of the time
dedicated to GPGPU, and they clearly indicated their dedication to non-
rasterised rendering in the 2009-2010 timeframe. We suspect the same
is true for AMD.
The frequent implicit assumption that DX11 GPUs will basically be DX10
GPUs with a couple of quick changes and exposed tesselation is weak.
Even if the programming model itself wasn't significantly changing (it
is, with the IHVs providing significant input into direction), all
current indications are that the architectures themselves will be
significantly different compared to current offerings regardless, as
the IHVs tackle the problem in front of them in the best way they know
how, as they've always done.
The industry gains new ideas and thinking, and algorithms and
innovation on the software side mean target workloads change; there's
nothing magical about reinventing yourself every couple of years.
That's the way the industry has always worked, and those which have
failed to do so are long gone.
Intel is certainly coming up with an unusual architecture with
Larrabee by exploiting the x86 instruction set for MIMD processing on
the same core as the SIMD vector unit. And trying to achieve leading
performance with barely any fixed-function unit is certainly
ambitious.
But fundamentally, the design principles and goals really aren't that
different from those of the chips it will be competing with. It will
likely be slightly more flexible than the NVIDIA and AMD alternatives,
let alone by making approaches such as logarithmic rasterisation
acceleration possible, but it should be clearly understood that the
differences may in fact not be quite as substantial as many are
currently predicting.
The point is that it's not about rasterisation versus raytracing, or
even x86 versus proprietary ISAs. It never was in the first place.
The raytracing focus of early messaging was merely a distraction for
the curious, so Intel could make some noise. Direct3D is the
juggernaut, not the hardware.
"First, graphics that we have all come to know and love today, I have
news for you. It's coming to an end. Our multi-decade old 3D graphics
rendering architecture that's based on a rasterization approach is no
longer scalable and suitable for the demands of the future." That's
why the message got so muddled, Tom. And no offence, Pat, but history
will prove you quite wrong.
http://www.beyond3d.com/content/news/631