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Parallella, a $99 Linux Supercomputer

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Re: Parallella, a $99 Linux Supercomputer

#61
post #39
post #15

Earlier quoted context omitted.

Comparing it with a GPU is a natural discussion to have. I believe there is more information on their website to answer the question. But maybe someone else can explain the programming paradigm difference. http://www.adapteva.com/introduction/

Each of the 64 cores can independently run arbitrary C/C++ code, which is much more flexible than a GPU. Each core has 32KB of local memory, which can also be accessed by the other cores, and there's 1GB of external memory too. Specs: http://www.adapteva.com/products/silicon-devices/e64g401/ Architecture: http://www.adapteva.com/wp-content/uploads/2012/10/epiphany_... SDK docs: http://www.adapteva.com/wp-content/uplo…

Interesting architecture. I like how well-documented everything is. Usually, either the low-level ISA for accelerator chips is not documented at all (like with GPUs), or detailed documentation is only available under NDA, and only proprietary development tools are available (like with FPGAs).

The topology reminds me of this paper "The Landscape of Parallel Computing Research: A View from Berkeley" http://www.eecs.berkeley.edu/Pubs/TechRpts/2006/EECS-2006-18...

Re: Parallella, a $99 Linux Supercomputer

#62
post #50

I'm really disappointed about how shallow the discussions about Adapteva are, and have been, on HN. To remind everyone, the H = hacker. This device is a godsend, as far as I'm concerned. For the first time ever I get fully documented access to compute array on chip. No the architecture wasn't designed for anything specific, like graphics, but that means I don't get bogged down in details I don't care about, like some…

Good reminder!

Do you see applications in an embedded sense, or are you looking at it to augment a regular computer's capability?

Re: Parallella, a $99 Linux Supercomputer

#63

Earlier quoted context omitted.

Much, much less than the specialized ASIC platforms do.

But when we consider the consuming power of ASIC platform, I think this board has strength. They said this board consumes 5 watt for typical jobs. https://en.bitcoin.it/wiki/Mining_hardware_comparison

> But when we consider the consuming power of ASIC platform, I think this board has strength.

No, it can't possibly have.

SHA is half bitshifts-by-constants. On an ASIC platfrom, those essentially refactor to no-ops. There is no way, no how general-purpose hardware could ever possibly get anywhere near even a piss-poor special purpose ASIC for this task. If you think otherwise you simply don't understand the domain. Those 600-watt ASIC systems contain multiple chips and run at tens of GHashes/s. That 5-watt chip, if it's very, very good, might maybe break 40MHash/s.

Re: Parallella, a $99 Linux Supercomputer

#64
post #48

Earlier quoted context omitted.

A typical GPU can execute a small number of threads on a large number of streams of data carefully laid out in memory. Every time you want to do something conditionally on just one data stream, you waste a lot of capacity. In contrast, the Epiphany chips can execute individual threads on each core in parallel on data either local to the core (fastest), on any other core, or in separate main memory. The current Epipha…

This might be a really stupid question: How difficult would it be in the practical sense to keep all of the cores on something like this "fed" with enough information to get benefits from its concurrency? I mean to "feed" all 64 cores enough data/code so they can all "do something" concurrently is one hell of a job all on its own!

Depends a lot on the type of problem, and I think that's going to be what makes or breaks them. They have some good examples, but you're right, it's a hard problem and one of the reasons it's so important for them to get these dev boards out.

Re: Parallella, a $99 Linux Supercomputer

#66

As someone who uses supercomputers, I'm not sure I entirely understand the market of this product. It's really cool and I'd love to have one to tinker with, but due to its high parallelization, I see no benefit of using this over a graphics card. I'm not sure if $99 can get you a GPU that reaches 90 GFlops though... perhaps that's where the benefit lies. EDIT: After reviewing their website, I notice they state > One…

I think this may just be a novel way to sell a dev board for their custom silicon and get some of that heavy kickstarter press coverage.

If you figure that what they're really trying to do is get people familiar with it and see how well it might augment one of their existing ARM products it starts to make a lot of sense.

For instance I have a low end 4 bay arm based nas. It's insanely modest specs (1.6ghz single core + 512MB ram) actually are quite sufficient for most nas tasks. But it's really more like a home server platform as they have all sorts of addons that include things like CCTV archiving, DVR, ip pbx - you get the picture. But if you really start treating it like a general purpose server you quickly realize that some common workloads perform horribly on that arm core and it's frustrating.

It can easily push 800mbps or so with nfs smb or cifs, but if you want to rsync+ssh you're looking at less than a 10th of that because of the various fp needs of that chain. Native rsync with no ssh/no compression does somewhat better but still poorly due to its heavy use of cryptographic hash functions for delta transfers.

There are plenty of other examples - file system compression, repairing multipart files with par2 (kind of like raid for file sets). Face detection, file integrity hashing) And if it could do on the fly video transcoding (don't even think about it) it could happily replace another full system i have running plex server.

There's probably a lot of devices that the designers default to arm but have to skip features that are heavy fp. If somebody in the firm has played around with a chip you can just drop in and not change your soc or toolchain that starts sounding pretty good i'd guess - and likely still far cheaper than an atom soc.

Re: Parallella, a $99 Linux Supercomputer

#67
post #46
post #14

Earlier quoted context omitted.

Supercomputer =/= "a fast computer".

Then what is it? Wikipedia also seems to say it's "a fast computer": "a computer at the frontline of current processing capacity, particularly speed of calculation" https://en.wikipedia.org/wiki/Supercomputer

A supercomputer is a machine that's I/O bound instead of CPU bound, at least as a first approximation.

You'll get lots of specs thrown at you like in mid 2013 a supercomputer means using X, Y, and Z technologies. But that is just a longer format version of the above.

A pessimist usually warps the definition to a machine that's primarily programmer limited rather than CPU or I/O limited, LOL.

Over the decades as parallelism has been popular its drifted more toward being financially limited more so than anything else, in the long run this is probably going to be the new definition, a overall system who's performance is solely limited economically. You might think thats all computers, not so, there's plenty which are inherently limited by architecture to low performance, or limited by programming to single core / single thread tasks.

The biggest bummer of supercomputers in the parallel era is no one is doing anything about latency. That's nice that your 2000 processor design with 20 deep pipelines eventually after enormous latency can really churn stuff out, but the olden days pursuit of low latency resulting in speed was pretty interesting technologically. Hilariously you'll even get noobs who don't even understand the difference between latency and speed or claim there isn't one.

Re: Parallella, a $99 Linux Supercomputer

#68
post #50

I'm really disappointed about how shallow the discussions about Adapteva are, and have been, on HN. To remind everyone, the H = hacker. This device is a godsend, as far as I'm concerned. For the first time ever I get fully documented access to compute array on chip. No the architecture wasn't designed for anything specific, like graphics, but that means I don't get bogged down in details I don't care about, like some…

ask what future things having something like this on a SoC would enable.

I asked that and came up blank. And I haven't seen answers from anyone else, either. Has Adapteva themselves shown any examples where their chip beats a GPU?

Re: Parallella, a $99 Linux Supercomputer

#70
post #45

I backed this project simply because it's a great idea to build a very small highly parallel computer that runs on very little power. Maybe this one won't hit it out of the park but it might give other people ideas. Building the first one of anything is always hard. Add a little serendipity and we might get an entirely new use for computers. Just saying that I could do more with a $99 graphics card sort of misses the…

It's such a great idea that AMD Kabini already did it.
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