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Parallella, a $99 Linux Supercomputer

zdnet.com

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Re: Parallella, a $99 Linux Supercomputer

#121

Post by lgeek »

wladimir wrote: post #61
mkl wrote: post #39

Earlier quoted context omitted.

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.ber…

> the low-level ISA for accelerator chips is not documented at all (like with GPUs)

Let me show you the AMD Southern Islands ISA specs: http://developer.amd.com/wordpress/media/2012/10/AMD_Souther...

Re: Parallella, a $99 Linux Supercomputer

#123

Post by jholman »

ludston wrote: post #27
Xcelerate wrote: post #7

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…

Could it be good for path finding and other NP Hard problems? It could do good things for the AI world if that's the case.

First of all, which is the NP-hard pathfinding problem you're talking about? When I hear "pathfinding" I think "shortest path", which is (deterministic) polynomial time (exact class dependant on exactly which variant of the problem, but even Floyd-Warshall is Θ(|V|³)).

---

Anyway, no. If you have an NP-hard problem, and you want an exact answer (i.e. you are denying yourself approximate solutions), and you want to solve it for large inputs, unless you have either proven that P=NP by construction (heh), or you have a non-deterministic computing machine (heh), you're basically screwed. Going parallel isn't going to help, any more than a hypothetical billion-GHz serial CPU is going to help. Asking this question suggests a fundamental lack of understanding about what is interesting (or rather, infuriating) about NP-hard problems.

Parallel processing models give you, at best, linear speedup. If your problem is O(too-big), and your input is large, linear speedup doesn't help, no matter how much linear speedup you have.

Re: Parallella, a $99 Linux Supercomputer

#124

Post by qb45 »

mmanfrin wrote: post #103

Can someone explain to me how a $99 computer can have 45ghz of processing power, but an i7 costs 3x that for 1/10th that clock speed? What does this $99 miss out on that my i7 has the capability of doing?

First of all, this 45GHz figure definitely isn't valid for modern x86 chips - thanks to multiple cores and SIMD instructions they reach few dozen GFLOPS at stock frequencies.

Furthermore, x86 chips pack all of their performance in low number of cores, what makes them much more useful for common scalar code. And if 20 times higher scalar performance isn't enough to convince you to pay premium, the complexity required to achieve this level of scalar performance definitely is enough to discourage Intel from selling you i7s for $99.

Re: Parallella, a $99 Linux Supercomputer

#125

Post by lelandbatey »

phaet0n wrote: 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…

My biggest question is what do I need to know to use this? How can I write things that take advantage of this massive parallelization? Is there any reading anyone would recommend? Or maybe some basic examples for writing GPU based parallel software?

How can we get started with this?

Re: Parallella, a $99 Linux Supercomputer

#126

Post by qb45 »

backprojection wrote: post #122

How does this compare the the new Intel MIC (Xeon Phi) co-processor boards? I think they claim 1TFLOP. Can we think of this as a low-powered alternative? http://en.wikipedia.org/wiki/Intel_MIC

The general idea is similar - lots of cores with distributed SRAM memory and some shared DRAM, all sitting on 2D mesh network. The main difference is that Epiphany is made of custom simple RISC cores, while Xeon Phi uses 1st gen Pentiums with huge SIMD FPUs slapped on for higher FP throughput (and TDP).

Re: Parallella, a $99 Linux Supercomputer

#127

Post by trotsky »

NewAccnt wrote: post #107

I wonder how those in the performance computing sector feel about running a proprietary supervisor with built in DRM on each and every CPU? Raspberry users might not care when for just hobbyist applications, but I doubt any serious scientist is going to overlook that. http://www.arm.com/products/processors/technologies/trustzon...

Intel platforms have a very similar risk via SMM and the platform code & controller. It's less advanced, but it can easily exert full control over the system without the os allowing it, minus access to some registers and on die cache. It could DMA in or out of the gpu memory as well.

Whether your soc vendor forces a secure supervisor to load is up to them, and i'd be surprised if an HPC builder had trouble finding vendors to supply parts with a totally controllable boot chain.

I'm sure there are ways to obscure it, but there are just as many ways on x86 platforms, the only real difference being that you could pull the eprom and reflash it and inspect the other board components. There's also plenty of evil things you can put in a soc without relying on trustzone.

Bottom line is you have to trust your vendor. If you want a soc integrated and fab monitored by a business/state that is politically aligned with yours it is probably just a matter of paying a premium.

Re: Parallella, a $99 Linux Supercomputer

#128

Post by qb45 »

NewAccnt wrote: post #107

I wonder how those in the performance computing sector feel about running a proprietary supervisor with built in DRM on each and every CPU? Raspberry users might not care when for just hobbyist applications, but I doubt any serious scientist is going to overlook that. http://www.arm.com/products/processors/technologies/trustzon...

The hardware cost of TrustZone is rather low and vendors of "compute SoCs" have no reason to ship hypervisor software on their chips.

And Raspberry Pi probably doesn't run any secure mode hypervisor as well.

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