New guide: Bake your own Raspberry Pi Lego-crust cluster Scientists at the University of Southampton have built a "supercomputer" from Raspberry Pis lashed together to form a colourful data-cruncher. Professor Simon Cox and his team racked up 64 credit card-sized Pis using Lego building blocks to create the parallel computer. They named their beast Iridis-Pi after the university's …
I always wanted to build a web server using a cluster of Pi, but turned out after reading a few things online it's less than satisfactory. Instead I'm waiting for the Ouya, sure it costs 3 x more, but it has twice the RAM, and four times the cores. I figure what I would have spent on Pis, I can grab four Ouya, and use a pair of Pi for load balancing.
For a few bucks more you don't have to wait. An Odroid X carries Samsung's quad core Exynos 4412 and goes for $129. Sure the $40 shipping from Korea stings a little bit but it goes down per board when you get multiples. The ones I ordered took about two weeks to deliver, now I just need a free weekend to play with them.
Have we gotten to the point where a $35 computer can play mame games without massive frameskipping? I've been out of the mame scene for a while. Years ago, I built my own arcade control box (with movable buttons and joysticks) that plugged into a computer (hacked keyboard). it would be cool as hell if I could put the whole computer in there too!
Apparently it will do some of the older mame games, but then again, you need a lot of beef to play the latest ones. The point of the mame project is accurate emulation rather than playability after all.
I got mine a few days after ordering from Farnell. Got it last week and it's now running OpenVPN through my router, so I can get into my home network when I'm out and about. It's got a 32GB flash card in it, which is plenty, and I can also wake up my other computers using WOL. Just need to get rsync up and running.
I was hoping to connect an old web cam to it but it draws too much current. Might try a powered hub but I expect a more modern web cam would make more sense.
I've always used Slackware and it seems to work fine on the Pi.
I don't think there's a reg has a supercomputer benchmark yet (I'm thinking a good measure of FLOPS is the "facebook IPO"), but 72 teraflops would have qualified as a supercomputer as recently as 2007 or so (the Cray XT4 was about this fast). It's certainly nothing special now in terms of performance - a modern xeon workstation would be a couple of orders of magnitude faster at least - Moore's law does horrible things to 5 year old technology.
Still, really cool, and the lego processor rack is nifty.
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Yeah, I made all sorts of mistakes here. I thought the 72TF number was the measured speed of the pi cluster.No speed number is given, as you say, that's the speed of their locally-built supercomputer.
And then I got giga and tera reversed in my head when I was trying to fit the speed on the top500 list, and divided the speed by a thousand, oops! 72TF would be about 415th on the top500 list, and about 3 orders of magnitude faster than a modern xeon workstation. Never mind!
The only reason I'm not withdrawing the original message is that I think "facebook IPO" as a measure of FLOPS is still pretty finny.
I love this implementation, and the link to the UNI blog was a fantastic step-by-step on the IT install, and even some good pics to use as a Lego guide... :)
One thing I will say, is that for a group of techies, they really didn't get creative with the power supplies! That many power strips and each RPi getting it's own mains-connected adapter?
One fo the great RPi features is the simple, 5v DC power input... any old 5v will work when pinned properly to a proper USB cable... so I would believe that a single DC adapter capable of providing sufficient amperage at 5v would work fine...
The RPi, I believe, will demand up to 500mA... if that is the case, they would need to be able to provide 32A of 5v power... something that should be able to be done with at least just a few old PC power supplies, or even just 2 enterprise grade server power supplies from old servers... very little involved in splicing in the required octopus of cables needed for the multiple drops... but would be more efficient, for sure, and much less complex.
Cheers!
A PC power supply will be VERY unhappy supplying many amps at 5V and none at 12V. It may refuse to work with that load, overheat and emit smoke, or simply waste a large fraction of the power going in. They're designed for use with modern PC hardware, with the lion's share of the power being consumed at 12V.
Just source a single-voltage power supply that delivers enough amps at 5V. There will be plenty of PSUs to choose from at RS or CPC. It may be cheaper to use multiple 5V 4A or 5A "bricks" than a single (say) 40A unit, and may also be easier to wire up.
"A PC power supply will be VERY unhappy supplying many amps at 5V and none at 12V."
Could you string a bunch of 7805s (http://www.raspberrypi.org/phpBB3/viewtopic.php?f=62&t=14512) off the 12V rail?
Or now that you can back-power (if I read it correctly) off a USB hub with the new revision... maybe(?)
You could do that, the 7805 is a really nice chip. You'd need to wire up a bunch of them and screw them to a heatsink though. It's less work to use a powered USB hub, which would at least let a bunch of pies share the same wallwart.
What a mess of power cables! With my supernatural ability to get myself tangled in cords, I would have had this thing in pieces on the floor in minutes. Seriously, in the days of corded phones I frequently tied myself to my own chair if I got engaged in conversation for a while.
A PC power supply will be VERY unhappy supplying many amps at 5V and none at 12V
So far, none of the several dozen PSU's I've mistreated that way have refused to work. The only thing that will actually happen is that the voltage on the unloaded buses will rise a bit (the 5V output is the one used for regulation feedback) and this *may* cause some overvoltage limiter to kick in and shut the thing down, but this is not something I have encountered even once. It may be true of PSUs meant to power gaming systems with graphics cards that contribute significantly to global warming, run-of-the-mill PSUs can be used without mishap.
And that's the real point - although a cluster (Bramble) of raspi's doesn't have a very good performance figure on cycles per $, compared with a desktop for example, its is VERY cheap as a teaching device for parallel processing.
If course, if you could access to the GPU, you have 48 processors per Raspi to play with.
Hmm, if every family member gave me a Pi for Xmas that would be a decent start.
from the enquiring minds want to know (and are presently too lazy to read the blog) dept:
* can the graphics part of the Pi processor be used as a floating-point vector processor?
* what is the computation/communication performance ratio?
* Linpack performance?
I guess it will all become clear in time...!
I wonder how good these would be for ray-tracing/CGI? Have seen other articles on using a bunch of MBs to make a "supercomputer" that is the backbone for home CGI work.the articles claimed about a 15X speed up due to sending out the frames to all the cpus at once.
Maybe the Professor could get with the graphic arts dept and run a few benchmarks
It is really a good project. well done.
Probably not very good. Ray tracing tends to exercise the I/O an awful lot so even if you assign one pi to a particular section of the screen it'll still end up accessing other parts of the scene in a pretty random access pattern (rays bounce). With only a 100MBit connection (and the fact that the USB and Ethernet share a bus) it's easy to saturate the available data channels--a problem that only gets worse as you scale up (though working with different net topology and having more control nodes could definitely help, to a degree).
On the other hand, having the farm render a typical fractal image would be a perfect application for it since each screen section is typically independent of each other one.
Despite how impractical this thing is, I'd still love to have one. I'm sure it's also a great teaching resource in spite of (nay, even because of) its shortcomings, necessity being the mother of invention and all that.
... here's what looks like an interesting course on the Cambridge Computing Labs site.
I intend to work through it as soon as I have (a) a Raspberry Pi and (b) a lot more free time.
..Or am I? It's a piece of piss to downconvert 220 volts down to 5V with a switch-mode PSU. Jesus H. Wept, I did it a quarter of a century ago, when I was in my ealy 20's. About 90% efficiency, and I used an optical coupler for the feedback, and a 555 timer to fire the input transistors....(Fed by a humongous resistor, an effing big zener diode, and a bag of capacitors I could barely afford (low ESR)
Bloody wound the (toroidal) transformer myself. IIRC, I used a strip of copper, covered with sellotape for insulation, wrapped around the toroid, about 10 turns, to get the secondary output working....
OK, a few explosions on the prototypes, but.... My University Professor would have wet himself laughing, except...I never went to University...Self-taught from having no girlfriend worth mentioning, so living in my mom's house.....Nothing else to do....
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