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Low-cost Reconfigurable Computing (FPGA's)
Anonymous Coward writes: "People at the at Chinese University of Hong Kong have developed a reconfigurable computing card which uses the SDRAM memory slot instead of the PCI bus. Measurements in the paper show greatly improved bandwidth and latency - why aren't more people using this idea?"
the idea of FPGA computing has been around for a little while at least (look here for examples). i think Scientific American even wrote about "configurable computers" in 1997 or so. why aren't they more popular, then?
modern processors are well-adapted to general computing tasks.
FPGAs (read: custom iron) might be good for a few specialized tasks (breaking 3DES, for instance), but most of us will be a lot happier on our UltraSparcs and Athlons and G4s.
Catalina Research offers a card line called the "Chameleon" based on Virtix-E series FPGAs. This allows the card to provide millions of reconfigurable system gates that the use can apply. Connected to the FPGAs are independent blocks of ZBT static RAM which can support a single read or write operation per cycle. The Chameleon products have three high-speed IO daughtercard sites compatible with the industry PMC standard.
Chameleon VME Block Diagram
the byproduct of years of oppression by the white man
StarBridge Systems uses these to make their supercomputers that run in Standard ATX case... And I think they charge around $15 million for the low end models. These info came from a slashdot story but I can remember when and I don't have time to verify. I just remember CmdrTaco being very sceptical.
http://danisaacs.com/temp/fccm01_pilchard.pdf
Be gentle. And mirror and post mirrors, please. Bandwith costs, and I'm poor.
- Dan I.
I have also wondered why more people aren't using the memory bus for peripherals. For instance, the VGA adaptor would greatly benefit from that interface (3d work, video games), also, using that bus as a network connection in a renderfarm would probably be nice too. Seriously, the PCI buss can only offer so much (132 MB/S) which is certainly going to be a problem with anything faster than gigabit ethernet... Meanwhile, modern memory busses are upwards of 4.8Gb/s. Imagine multiple machines strung together with that kind of bandwidth between them!
Another question I've had bouncing around in the back of my head is why no one uses MPEG decoder circuitry for MP3 playback? All the players I've tried, windows or linux, take 10-30% of the CPU for noraml playback operation. This is unacceptable when working in big apps like 3DStudio Max, make-ing a big app or running big scripts. I have an old MPEG decoder card from a Creative DVD, also I believe my G-Force has MPEG decoder acceleration... How much trouble would it be to write a driver for Winamp that uses preferred devices like that?
:)Fudboy
I guess I'm only a Fudboy, looking for that real Transmeta
This may help a little, but in general, people haven't figured out how to make FPGA-based computing sufficiently useful, cheap, and easy in order for it to catch on. Programming an FPGA is still rather hard and the architecture limits severely what you can do. And there is the chicken-and-egg problem with the boards: if you write software for them, few people can run it, and few people are motivated to buy a board because there is no software that uses it. Right now, you are probably a lot better off buying a dual processor board or a cluster than an FPGA add-on.
Here is a PDF version
Top Most Bizarre/Disturbing Error Messages
Here is a PDF version Download all you want - I'm not metered (but its also only 384kbps :) )
Top Most Bizarre/Disturbing Error Messages
FPGA technology to replace (or more like having a "flashable") Current processors could/would be a great leap in computing, it would mean having a "soft-hardware upgrade", microcode or "sillicon" bugs could be addressed, but there would probably be the downside of everything else in the computing industry: companies would released bugged stuff, beta would go around like current drivers :), etc etc.
All this said, unless some big breakthrough happens, we won't see out Athlon or Pentium IV system replaced by these, the 2 main limitation of FPGA are the number of available gates, and the speed at which they operate.
While they've managed to increase the number of gates to something quite big (last time I read about this I think it was in the low million? 1 or 2, but I can't be sure), this is enough to "emulate" microcontrollers or lower end processors, but not enough for higher end microprocessors. While eventually they will catch up and maybe someone will do his thesis on emulating an Athlon off FPGA stuff, by that time we'll be at the 2nd or 3rd rev of Post-hammer processors, so it will look like today being able to emulate a 486 (granted, there could be some use in that, but none come to mind right now.. parrallel processing? 1 athlon can replace zillion of 486s...) Also the developpement of microprocessor is going at a faster pace than FPGA technology. I am not saying this couldn't happen, but it would need a serious bump in the fab process and technology to be able to reach Ghz speed, and probably few 100M's of gates.
Still, it's a very interresting technology.
--- Metamoderating abusive downgraders since my 300th post.
Using memory slots for devices is a bad idea. The interface is not designed for devices. There are no IRQ lines. The address space can be configured by the chipset to fall anywhere in the address space of the whole machine (your device may end up starting at 0). The address space may even be interleaved with other memory devices in other slots. And the next generation of memory will use a whole different interface, and most new motherboards will soon migrate to it with little concern for backward compatibility.
now we need to go OSS in diesel cars
Would there be any speed advantage to useing a reconfigurable chip vs. a programmable DSP for a very processor intensive task, like MPEG encoding or real-time full-screen graphics rendering? (think Fractal Flames as a music visualization plug-in) Assume that all your algorithm code can fit in on-chip cache or high-speed L2 so you don't clog up the memory bus)
There are several FPGA cpu's available already. For loadsadetails, go to http://www.fpgacpu.org/ and see just how easy it is to create a CPU. I've even managed to (starting with Jan's work) build my own without any prior knowledge of verilog.
The main drawback is always going to be speed though - it's simply far and away more complex to have reconfigurable hardware than static h/w. The current "hot" CPU of any generation will almost certainly never be reconfigurable!
Simon.
Physicists get Hadrons!
I find it very interresting that a Chinese Universesity is allowed to use a board produced in Taiwan. Maybe it is just too hard to find a board, that isn't produced in Taiwan.
Jan
as expansion slots were used by a few companies that sold G3 expansion cards for older PowerMacs.
IIRC, they had an expansion card that you'd attach to the cache slot near the original PowerPC CPU.
This way the new CPU would have all the memory bandwith it needed to run at 400 Mhz. 400 Mhz in a performa 6200... wow!
What ? Me, worry ?
Not that I'm recommending using the memory bus for 3d, but...
PCI/AGP are great for uploading static textures, on that you are correct.
However, there's more data than that to saturate the bus:
* Procedural textures
* Vertex cloud animation (bones aren't always appropriate!)
* Swapping textures when insufficient video ram is available.
Any of these can cause bus saturation. While many games are following the Half-Life model (static everything, use matrix driven hierarchical bones animation), this creates pretty bland worlds.
If you want to realistic water, more organically animated content, or more subtle animations, this bandwidth becomes critical. Vertex/pixel shaders regain some of this by allowing processing to be moved back into the 3D GPU, but that only works for inherently procedural and low order polynomial effects - data driven or more complex procedurals still need to upload obscene amounts of data!
I should also mention that accelerator card drivers are optimizing pipelines for static textures, Unreal ran into this problem badly, and it continues to this day.
If Gates were reprogrammable, then we wouldn't be in this mess in the first place.
Bowie J. Poag
On FPGAs as PC Coprocessors, redux:
http://www.fpgacpu.org/log/aug01.html#010811
On FPGAs as PC Coprocessors (1996):s sors.html
http://www.fpgacpu.org/usenet/fpgas_as_pc_coproce
http://sage.che.pitt.edu/~harrold/tmp/fccm01_pilch ard.pdf
-- john
For all intent and purpose new graphics and sounds cards are programmable to do specific operations. The gate logic doesn't change -- it's a microcode fix. Ends up being basically the same thing in the end for them as long as you don't try to coax them to do other things (like analog logic) they'll be just as good.
Rod Taylor
Memory has become ridiculously large and cheap. 512MB boards are under $50. I'm sure there are people who need more than 1GB on a non-production machine (obviously production machines like database servers need all they can fit), but for most applications, by the time you need to fill the third memory slot on your box, you could just as well buy a new card that's 4X larger than the old one you're rolling out.
If you've only got two slots, you may have problems, but usually the main time you need the third slot is if you're upgrading a machine and want to keep the old memory as well. And sometimes you've got a board that doesn't have enough address lines or has a BIOS that doesn't understand them (my home machine *says* it can use 3x256MB memory, but it looks like I'll have to flash a new BIOS to do it, and so far 192MB has been plenty.) :-)
If you don't have something else special to do, like FPGA, you might as well keep the old RAM - doesn't hurt, and more memory is always usable as long as it doesn't force you to a lower speed. I recently added 512MB to a 128MB maachine at work, giving 640MB. Bill Gates says that ought to be enough for anybody
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
I am afraid that I must disagree with many of the comments posted concerning FPGAs. First off, FPGAs have been successfully demonstrated in the multiple GHz frequency range using SiGe as a base material (Dr. Jack McDonald's group at RPI has done such an implimentation with SiGe BiCMOS based systems.) Further, the contention that FPGAs are "difficult" to program, is I believe an oversimplification of the hardware/software relation in general. Are FPGAs more difficult to program than to implement C++ code on a PC? Yes, but they are also significantly more powerful pieces of hardware than the current computer architecture. For example, one of the most visionary uses of high speed FPGAs would be to replace component cards in the PC of today. For example, in a base system today, one typically has a video, audio, and I/O type card (i.e. hard disk/floppy disk/CD-CDRW-DVD). Imagine now a computer that consists of a large number of FPGAs, essentially reconfiguarable hardware. Now drivers can be reset on the fly, power up ready OSs with no boot time (using non-volatile configurations), and a host of other interesting and desirable properties are possible. If you want to send email the FPGA bank can reconfigure itself into a network or wireless ethernet card. This has some significant advantages over the current paradigm.
Several readers commented concerning the adoption of FPGAs is not going to happen quickly(i.e. no development support) or that the problems with bus interface speeds are nontrivial. However, these difficult problems are not the problem of the hardware, and attempting to interface it to the standard PC, however kludgy, is a rational approach. Criticizing the implimentation here is a bit like telling someone that they should have used a Porsche instead of a Pinto to build a time machine.
Well, while I was doing my final year project at Department Of Computing, Imperial College London we have the actual card made by Chinese University of HK. Bascially it is just a matter of having a SDRAM contoller "programmed" onto the FPGA, and wired correctly(it uses Xilinx Virtex series of FPGA, and Xilinx has implemented a SDRAM controller on it - see their tech notes - their sites is down when I write this). Having done my project with FPGAs, I would say the problem with this thing is that it is very fiddly to program the thing - it requires the understanding of software as well as hardware. I also agreed with some comments above that it lacks interrupts on SDRAM bus - therefore it is even more difficult to program the card.
Anyway, PCI FPGA cards has always been available, and they are hugely expansive. But they are getting down in price. One of the problem of FPGA is that the speed of the chips are slow (depends on the complexity of the circuit, you can only clock it to around 1Ghz for very simple cores, lot slower for complex circuit) so consider the speed of microprocessor it is not worthwhile to use them in normal computer systems - but a new niche is open up in embedded market.
Notice the name of the university is right! Chinese name of the university suggested that the "Chinese" in the university name is actually means Chinese language, not China the country.
Back when machines came with 4K of memory (yes, K, not M), but could address 64K, it wasn't uncommon to memory map devices. It was an easy thing to do; a few discrete nand gates (7400 series ICs) for decode logic and you were done. Since a lot of the code was written in assembler then, it was easy to move stuff in and out of the memory locations.
:-)
Everything old is new again... I wonder how many other ancient techniques would be useful now...
Anyone remember hardware memory swaping (bank switching)? You could take that machine with a measly 8GB memory limit and expand to 256 banks of 8GB for 2TB of memory (assuming you could afford all that) with a single memory mapped bank select byte. Only 1 memory access cycle to swap 8GB.
Actually, that might be pretty cool.
Can You Say Linux? I Knew That You Could.
Comment 1 RE:Linked directly to Postscript?
Try using ghostscript/GSView which will display the postscript file directly. (A quick search on Google gave the following link which should be useful
GhostScript
Comment 2: I don't think this is ever really likely to be part of 'consumer' system. FPGA's are great for
1) prototyping circuits that will later be implemented as an ASIC where the cost of "respinning" a chip is extremely high or
2) Situations where the system is only produced in very small numbers.
The main problems with FPGAs are that they are
1)Expensive!.
2) Relatively small in terms of the gates they can implement and
3) The clock speed that can be achieved is probably about an order of magnitude lower than an equivalent ASIC.
For many situations a multi-CPU system may be a much better option, and I certainly think that they'd be impractical for a mass produced system.
Simon
hahahaha yeah I know lmao fuck dem moderators they come from goatse or somewhere
"I have not failed. I've simply found 10,000 ways that won't work." --Thomas Edison