AMD's Graphics Core Next Preview: AMD's New GPU, Architected For Compute
by Ryan Smith on December 21, 2011 9:38 PM ESTFinal Words
As GPUs have increased in complexity, the refresh cycle has continued to lengthen. 6 month cycles have largely given way to 1 year cycles, and even then it can be 2+ years between architecture refreshes. This is not only a product of the rate of hardware development, but a product of the need to give developers time to breathe and to absorb information about new architectures.
The primary purpose of the AMD Fusion Developer Summit and the announcement of the AMD Graphics Core Next is to give developers even more time to breathe by extending the refresh window backwards as well as forwards. It can take months to years to deliver a program, so the sooner an architecture is introduced the sooner a few brave developers can begin working on programs utilizing it; the alternative is that it may take years after the launch of a new architecture before programs come along that can fully exploit the new architecture. One only needs to take a look at the gaming market to see how that plays out.
Because of this need to inform developers of the hardware well in advance, while we’ve had a chance to see the fundamentals of GCN products using it are still some time off. At no point has AMD specified when a GPU will appear using GCN will appear, so it’s very much a guessing game. What we know for a fact is that Trinity – the 2012 Bulldozer APU – will not use GCN, it will be based on Cayman’s VLIW4 architecture. Because Trinity will be VLIW4, it’s likely-to-certain that AMD will have midrange and low-end video cards using VLIW4 because of the importance they place on being able to Crossfire with the APU. Does this mean AMD will do another split launch, with high-end parts using one architecture while everything else is a generation behind? It’s possible, but we wouldn’t make at bets at this point in time. Certainly it looks like it will be 2013 before GCN has a chance to become a top-to-bottom architecture, so the question is what the top discrete GPU will be for AMD by the start of 2012.
Moving on, it’s interesting that GCN effectively affirms most of NVIDIA’s architectural changes with Fermi. GCN is all about creating a GPU good for graphics and good for computing purposes; Unified addressing, C++ capabilities, ECC, etc were all features NVIDIA introduced with Fermi more than a year ago to bring about their own compute architecture. I don’t believe there’s ever been a question whether NVIDIA was “right”, but the question has been whether it’s time to devote so much engineering effort and die space on technologies that benefit compute as opposed to putting in more graphics units. With NVIDIA and now AMD doing compute-optimized GPUs, clearly the time is quickly approaching if it’s not already here.
Larrabee As It Was: Scalar + 16-Wide Vector
I can’t help but to also make a comparison to Intel’s aborted Larrabee Prime architecture here. There are some very interesting similarities between Larrabee and GCN, primarily in the dual vector/scalar design and in the use of a 16-wide vector ALU. Processing 16 elements at once is an incredibly common occurrence in GPUs – it even shows up in Fermi which processes half a warp (16 threads) a clock. There are still a million differences between all of these architectures, but there’s definitely a degree of convergence occurring. Previously NVIDIA and AMD converged around VLIW in the days of the graphical GPU, and now we’re converging at a new point for the compute GPU.
Finally, while we’ve talked about the GCN architecture in great detail we haven’t talked about how to program it. Of course there’s OpenCL, but with GCN there’s going to be so much more. Next week we will be taking a look at AMD’s Fusion System Architecture, a high-level abstraction layer that will make GPU programming even more CPU-like, an advancement necessary to bring forth the kind of heterogeneous computing AMD is shooting for. We will also be taking a look at Microsoft’s C++ Accelerated Massive Parallelism (AMP), a C++ extension to bridge the gap between current and future architectures by allowing developers to program for GPUs in C++ even if the GPU doesn’t fully support the C++ feature set.
It’s clear that 2011 is shaping up to be a big year for GPUs, and we’re not even half-way through. So stay tuned, there’s much more to come.
Facebook
Twitter
RSS
83 Comments
View All Comments
Targon - Saturday, June 18, 2011 - link
With Windows 7 having a 80 percent(or higher at this point) install base being 64 bit, it will take until late 2013 before we see the majority of the old 32 bit install base being phased out in the home computer market(as people replace their computers at the four-five year mark). Until then, application developers have to expect that they MUST support both 32 and 64 bit platforms. Lowest common denominator for your user base is what developers generally have to compile for.DanNeely - Saturday, June 18, 2011 - link
I assume you're using the steam hardware survey since they're showing 4:1. Unfortunately steam's not a good source for broad market stats since it excludes the low end boxes bought by non-gamers and corporate boxes. Surveys that capture these numbers only show a 2:1ish ratio for win7 64:32.Beyond that, it's the people with the low end 32bit boxes that will keep their old clunkers the longest. You're also underestimating how long support for legacy OSes will continue despite their very small market shares. Firefox 4 still runs on win2k, despite it's market share having been negligible for several years and being officially out of support for almost a year.
Excepting apps that actually can benefit from going 64bit I expect most to stay 32bit for at least the next 5 years.
swaaye - Saturday, June 18, 2011 - link
Indeed. In the non-gamer realm, I know of people happy with 2003 Pentium 4s and Athlon XPs yet. I have no doubt that there are many people with even older hardware. This stuff tends to stick around until the PCs die and the owner is told it's not worth the money to upgrade. Fear of change and the simple lack of a true need to upgrade is the reason.swaaye - Saturday, June 18, 2011 - link
Oops. I meant that the owner is told it's not worth the money to fix the dead old hardware. But they do also tend to ask about upgrading their ancient box too.Randomblame - Saturday, June 18, 2011 - link
I was at office max the other day and a guy was screaming at a sales rep because they didn't carry any serial mice that supported his rig. I don't mean ps2 either. He was carrying around a busted up brown serial mouse. He said his rig came with windows 95 but last year he upgraded it to windows 98. Seriously. This is the world we live in.EJ257 - Saturday, June 18, 2011 - link
I still have my Compaq (that came with Win95 which I upgraded to win98) running on a Pentium 133 with 32MB of EDO RAM and a 2.1GB HDD. Its sitting ilde in my basement collecting dust at the moment. :DOperandi - Sunday, June 19, 2011 - link
But Steam is good representation of those who could benefit from and will ultimately will be using these future technologies, professionals and enthusiasts. Such is always the way of high-end computing.softdrinkviking - Monday, June 20, 2011 - link
exactly. people still running XP are probably not the target market for developers because if they are so slow on the uptake of new technology, it would follow that they are also relatively uninterested in other new programs.Targon - Sunday, June 19, 2011 - link
Nope, I am going on what my customers have and are upgrading to. If you BUY a machine with Windows 7 on it, 9 out of 10 have Windows 7 64 bit on them. Those that have 32 bit are either the very low-end machines with only 1GB of RAM(yes, they still sell those), or they are the result of doing an upgrade from Windows Vista 32 bit.That is the thing about 64 bit, people don't "go to 64 bit" at this point, they get a new computer that comes with 64 bit Windows on it. The number of people who do an upgrade on an older machine has dropped, since those who would have done the upgrade did that back in 2009 and early 2010 when Windows 7 first came out.
Now, the real benefit to 64 bit isn't as much about the software as it is about how much RAM the machine comes with. If you get a machine with 4GB of RAM, you want 64 bit, just so you don't lose memory due to the 4GB limit on 32 bit Windows, and hardware mapping below the 4GB mark.
A part of this is also about the area you live in, and how much money there is going around. I live in an area where it is the norm to pay over $8 per person for lunch at a deli, and as a result, the value of the dollar isn't as high. Spending $20/day just on lunch and minor expenses is the norm, so with that in mind, replacing a computer every 4-5 years, even for the non-technical is NORMAL. The last time I encountered Windows 95 or 98 was around 6 years ago.
UrQuan3 - Thursday, June 23, 2011 - link
There is a little more benefit. A few of us were doing an internal benchmark of our software using VStudio 2010 and all the random hardware we have around. 32bit, 32bit + SSE2, and 64bit + SSE2. We found across the board, 64bit is about 5-10% than 32bit + SSE2 and 5-20% faster than basic x86.However, a 64bit OS gave no benefit (or penalty) for a 32bit program. The same 32bit software ran the same speed on XP32, XP64, Vista32, Vista64, and 7-64.