Slashdot Mirror
End of The Von Neumann Computing Age?
olafo writes "Three recent Forbes articles:
Chipping Away, Flexible Flyers and Super-Cheap Supercomputers cite attractive alternatives to traditional Von Neumann computers and microprocessors. One even mentions we're approaching the end of the Von Neumann age and the beginning of a new Reconfigurable computing age. Are we ready?"
Of an Alfred E. Neuman computing age. I can't wait to see Dave Berg's take.
Roger Kaputnik where art thou?
riding round the world on an old motorcycle
-- (Score:i, Imaginary)
Von Neumann means a processor hooked up to a single memory that contains both the program and the data, executing instructions one at a time in a sequence.
Compare this to the Harvard architecture used on some embedded processors: a processor hooked up to two separate memories, one containing the program, and the other containing the data. This is useful when you have your program in an EEPROM and your data in a little static RAM. Two types of memories naturally fit into a Harvard architecture, though it's simple enough to do the same thing with some memory mapping circuits.
If tits were wings it'd be flying around.
Two requiring a subscription, and one a goofy PR piece about wingnut FPGA "computers" that cost 200Gs and up.
Anyways. The FPGA machines sound intriguing, but really arent as 'all powerful' as the non-techie Forbes piece makes them out to be. Not everything is parralellizable, not everything is conducive to dynamically altering the instruction set as you run it.
The traditional von neumman architecture is the best solution for many processing tasks, lots of stuff is just conducive to a sequentially operating processor. It's probably the best for all around general computing.
And 200 grand is probably better spent on a beowulf cluster of something than one of these boxes, but I'm sure they have a niche of usefulness somewhere.
I dont expect to see the traditional computer go anywhere anytime soon.
I don't need no instructions to know how to rock!!!!
I'm sure these articles mention the 'Von Neumann Bottleneck' which is a power distribution in instruction execution, as 10 % of the instructions get executed 90 % of the time.
But *I* say the REAL VNBN is that only 90 % of all computer scientists are only 10 % as smart as Von Neumann.
It's Christmas everyday with BitTorrent.
For those of you skeptics (like myself when I first saw the articles) and for those that didn't RTFA:
Allan Snavely, a computer scientist at the University of California at San Diego Supercomputer Center, has been using a Star Bridge machine for about a year. He says he originally contacted Star Bridge because he suspected the company was pulling a hoax. "I thought I might expose some fraud," he says.
But after meeting with Gilson and seeing a machine run, he changed his mind. "They're not hoaxers," he says. "As I came to understand the technical side I thought it had a lot of potential. After talking to Kent Gilson I found he was very technically savvy."
Silicon Graphics has also asked Star Bridge to send along a copy of its hardware and software. The $1.3 billion (fiscal-year 2002 sales) supercomputer maker wants to explore ways to make a Star Bridge system work with a Silicon Graphics machine.
Over the past two years Star Bridge has sold about a dozen prototype machines based on an earlier design to the Air Force, the National Security Agency and the National Aeronautics and Space Administration, among others. It has also sold seven of the new models.
Olaf Storaasli, a senior research scientist at NASA's Langley Research Center in Hampton, Va., has been using Star Bridge machines for two years and says they are very fast but not yet ready to handle production work at NASA. "It's really a far-out research machine," he says. "It's more about what's coming in the future. I would not consider it a production machine."
One problem, Storaasli says, is that you can't take programs that run on NASA's Cray (nasdaq: CRAY - news - people ) supercomputers and make them run on a Star Bridge machine. Still, he says, "This is a real breakthrough."
Von Neumann was smart enough that there is more than one thing named after him. A Von Neumann machine is a self-replicator. A Von Neumann architecture is a computer architecture where programs and data are stored in the same manner.
Sometimes the latter is also referred to as a Von Neumann machine.
Tom Swiss | the infamous tms | my blog
You cannot wash away blood with blood
Even hyperthreading is only a minor improvement in parallelism, exchanging one instruction pointer for a small number (2? 4?). Hardly a different architecture.
Okay, no. FPGAs are NOT going to completely change computing.
.o file.)
First, you have to understand what they are: basically an FPGA is an SRAM core arranged in a grid, with a layer of logic cells (Configurable Logic Blocks, in Xilinx's parlance) layered on top. These logic cells consist of basically function generators that use the data in the underlying SRAM to configure their outputs. Typically they are used as look-up tables (LUTs) -- basically truth tables that can represent arbitrary logic functions -- or as shift registers, or as memories. On top of THAT layer is an interconnection layer used for connecting CLBs in useful ways. The FPGA is re-configured by loading the underlying SRAM with a fresh bitmap image, and rebuilding connections in the routing fabric layer.
You write for FPGAs the same way you build ASICs. You use the same languages (Verilog, VHDL) and sometimes the same toolchain. The point being: this is HARD. Trust me, I've been doing it. Verilog is damn cool, but remember that you're still building this stuff almost gate-by-gate.
There are a number of tools out there that do things like translate 3GL languages (such as Xilinx's Forge tool for Java, or Celoxica's DK1 suite for Handel-C) to an HDL like Verilog. Other tools like BYU's JHDL are essentially scripting frameworks for generating parameterized designs that can be dumped directly into netlist (roughly equivalent to a
My job for the past several months has been to obtain and evaluate these tools. I can tell you that these tools are not there yet.
So what do you use FPGAs for? Well, for the next 5 years, likely one of two things: either really cheap supercomputers (which is what we are working on) or as a "3D Graphics card play." The supercomputing play is obvious, the the other one bears explanation.
Anything you can think of goes faster if you implement it in hardware. 3D graphics is a great example: most cards today consist of a bunch of matrix multipliers plus some memory for the framebuffer, and a bunch of convenience operations that you do in hardware as well (like textures and lighting and so on.) Because it's in hardware, it's way faster than anything you could do on a general purpose processor.
Now, the problem is that hardware means ASICs (until recently.) ASICs are only cheap in large volumes. Thus, for applications that are not mass-market (like graphics cards are) it is not practical to build out an industry building hardware accelerators for them.
That's where FPGAs come in. FPGAs cost more per ASIC, but less than ASIC in small volumes. This suddenly makes it practical to make custom hardware accelerators for almost anything you can think of.
This is also true of supercomputing: supercomputers are still general-purpose, just not THAT general-purpose. Your algorithm still benefits when you can just reduce it to logic and load it onto a chip. You might only be running at 200MHz, but when you get a full answer every clock cycle, you suddenly do a lot better than when you get an answer every 2000 cycles on your 2GHz processor.
So to get back on topic, where will we see FPGAs? Well, you might expect to see an FPGA appear alongside the CPU on every desktop made in a few years; programs that have a routine that needs hardware acceleration can just make use of it. (Think PlayStation 4, here.)
You might also see things like PDAs come with FPGA chips: if your car's engine dies, you can just download (off your wireless net which will be ubiqutious *cough*) the diagnostic routine for you car and load it into that FPGA and have your car tell you what's wrong.
Aerospace companies will love them, too. Whoops, didn't catch that unit conversion bug in your satellite firmware before launch? Well, just reprogram the FPGA! No need to send up an astronaut to swap out an ASIC or a board.
What you're NOT going to see is every application ported to FPGAs willy-nilly, because like I said, this stuff is not easy. I'm coming a
If you're running a 3D-accelerated PC game or modelling application, the majority of your computer's FLOPS are already consumed by a non Von Neumann computing device.
.13 micron CPU. Such a system would be VERY easy to program, a couple orders of magnitude more so than an FPGA. So even though it wouldn't have as much theoretical computing power as an FPGA, massively parallel CPU's are likely to win out because they have the best cost/performance when you factor in development cost.
For better or worse, most of the PlayStation2's computing power is locked up in a non Von Neumann architecture.
So the evolution of computing to non Von Neuman architectures isn't so much news as a gradual shift that began about 5 years ago with 3dfx, and is really starting to happen large-scale right now.
The justification for FPGA's in consumer computing devices could be seen as a generalization of the rationale behind 3D accelerators: they bring you the ability to get a 10X-100X speedup in certain key pieces of code that are inherently very parallel and have very predictable memory access patterns.
I think the timeframe for mainstream FPGA style devices is quite far off, though. They need to evolve a lot before they'll be able to beat the combination of a Von Neumann CPU augumented with several usage-specific non Von Neumann coprocessors (the GPU, hardware TCP/IP acceleration, hardware sound...)
Here are the major issues:
- You'll need a lot more local memory than these devices have now -- there is a very limited set of useful stuff you can compute given a 32K buffer (a la PS2) and significant setup overhead.
- The big lesson from CPU's (and I expect from GPU's in the next few years) is that things REALLY flourish once you have virtualization of all resources, with a cache hierarchy extending from registers to L1 to L2 to DRAM to hard disk. For virtualization to make sense with FPGA's, Star Bridge's quoted reprogram times (40 msec) would need to improve by about 10,000X. Without this, you can really only run one task at a time, and that task can only have a fixed number of modules that use the FPGA.
Even then, it's not clear whether the FPGA's will be able to compete with massively parallel CPU's. In 3 more process generations, you should be able to put 8 Pentium 4 class CPU's on a chip, each running at over 10 GHz, at the same cost as current