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Comment by rys | Hacker News Reader

I find it incredibly dishonest of Adapteva to equate it to a "theoretical 45 GHz CPU". There are much better ways to talk about the performance level of their hardware than that metric, especially given the rest of the text in their Kickstarter pitch is aimed at people who need to inherently understand the hardware's execution model in order to program it effectively.

The computing industry has established language and metrics to discuss computing performance and, while the waters often get muddied when the hardware is wide, that's a step too far.

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  This board should deliver about 90 GFLOPS of performance, or — in terms 
  PC users understand — about the same horse-power as a 45GHz CPU.

That doesn't seem too outrageous to me.

Edit: They state the real fact and then give another figure explicitly stating it's an attempt to translate this into a metric the average user can somewhat relate to.

According to http://en.wikipedia.org/wiki/FLOPS#Computing it seems that they're off by a factor of two, but I'm guessing that's just an honest mistake.

Second edit: I was under the impression that this was the result of dumbing down by a journalist, however it seems it's from Parallela itself. That is a bit disingenuous indeed.

Me neither. The only catch is that you can't get serial computation that fast, but I assume anyone buying something called "Parallella" would realize that already.

A single Ivy Bridge core has 8 Flops/MHz of computing power. 45GHz Ivy Bridge would be able to do 360GFlops.

If you are correct for the first clause(8 Flops/MHz), 45GHz of Ivy Bridge core has 360k Flops (8 Flops/MHz * 45GHz ==> 8 Flops * 45k).

It should read 8 FLOPS per cycle double precision. So a 3 GHz 4 core Ivy Bridge processor could theoretically peak at 96 GFLOPS double precision, 192 GFLOPS single precision.

8 double-precision flops/cycle/core is the correct figure for Ivy Bridge and Sandy Bridge. With Haswell adding FMA, that figure doubles again(!)

Hum, no. Sandy/Ivy Bridge can only execute 4 double-precision instructions per cycle per core, in the form of two SSE instructions per cycle (one instruction doing adds, the other doing muls, executed by different units).

Doing 8 double-precision instructions per cycle would translate to either four 128-bit SSE instructions, or two 256-bit AVX instructions per cycle, which is not possible (unless I did not keep track of the latest AVX capabilities).

The only reason it isn't a big lie is that it's an utterly meaningless statement. In any case it is a misrepresentation of what modern CPUs are capable of.

It is 90 GFLOPS at less that 5 Watts. That's not too shabby. Adapteva claims that the Epiphany cores have a GFLOPS/W ratio of 50.

See here: http://streamcomputing.eu/blog/2012-08-27/processors-that-ca...

Also, the boards for the backers feature a ZYNQ-7020 SOC by XILINX which sports a 1.3M Gate FPGA, available to the user. This ain't bad either.

Most others - like my MacBook here [1] - are advertising GHz / core not "summing" the cores.

So the statement "PC users understand" is false.

[1] http://store.apple.com/us/browse/home/shop_mac/family/macboo...

Because all of us dumb PC users measure performance in terms of "horse-power". :-)

They do answer that on their kickstarter page: http://www.kickstarter.com/projects/adapteva/parallella-a-su...

Why do you say the Parallella is a 45GHz computer?

We have received a lot of negative feedback regarding this number so we want to explain the meaning and motivation. A single number can never characterize the performance of an architecture. The only thing that really matters is how many seconds and how many joules YOUR application consumes on a specific platform.

Still, we think multiplying the core frequency(700MHz) times the number of cores (64) is as good a metric as any. As a comparison point, the theoretical peak GFLOPS number often quoted for GPUs is really only reachable if you have an application with significant data parallelism and limited branching. Other numbers used in the past by processors include: peak GFLOPS, MIPS, Dhrystone scores, CoreMark scores, SPEC scores, Linpack scores, etc. Taken by themselves, datasheet specs mean very little. We have published all of our data and manuals and we hope it's clear what our architecture can do. If not, let us know how we can convince you.

They are clearly wrong. The purpose of higher clock rates is to produce a given answer in a smaller amount of time (latency). The purpose of adding more processors (cores) is to produce more answers in a given time (throughput). They are free to report their results using any standard measurement of throughput. Their answer is weasely.

But then, clock rate is irrelevant to latency and throughput. Really matters how much more work per cycle you get done, how fast you can move IO, and the cost of throughput per watt (and whether the system can meet your requirements at all).

They are "clearly wrong" when talking to geeks about specific types of problems. For most most people this means nothing, and multiplying it is fine. And for a lot of situations where you are considering batch jobs, multiplying it is fine as a quick illustration. It is not as if the raw numbers tell you anything anyway, since the characteristics of the system are so unusual.

They miscalculated how people would interpret it, and got burned. But they've been clear about what it is they actually mean the whole time.

Their answer to 'Why do you call the Parallella a supercomputer?' is also pretty curious: ;)

> The Parallella project is not a board, it's intended to be a long term computing project and community dedicated to advancing parallel computing.

> The current $99 board aren't considered supercomputers by 2012 standards, but a cluster of 10 Parallella boards would have been considered a supercomputer 10 years ago.

Wait, what? :D (emphasis mine)

> Our goal is to put a bona-fida supercomputer in the hands of everyone as soon as possible but the first Parallella board is just the first step. Once we have a strong community in place, work will being on PCIe boards containing multiple 1024-core chips with 2048 GFLOPS of double precision performance per chip. At that point, there should be no question that the Parallella would qualify as a true supercomputing platform.

I read this as:

Why do you say the Parallella is a 45GHz computer?

This is a Kickstarter project. In order to be successful, we need to attract as much attention from spam blogs as possible. To do that, facts are not particularly useful. What we need is something exciting. If we say we have 64 cores, that's not exciting. 64? I've forgotten how to count that low. Similarly, if we say we have a 700MHz processor, most people listening to us talk will actually start laughing in our faces. So that's no good. But thanks to our mathematical forefathers, there are many ways to make small numbers big. We could add the two numbers, saying we have a 764MHz machine. But that's not exciting, and the units don't work. We could divide the two numbers, yielding 10.94MHz. The units work, but that number is even smaller! Finally, we could try multiplication! And, boy, does that deliver! 45GHz!

TLDR: The only reason you're here is because of our misleading and dishonest claim. But now you're here. Please cough up your hard-earned cash which we might not use to go on a nice tropical vacation. You can trust us, we'd never mislead you...

I don't see a big difference between this and "petaflops" measurements that are the de-facto standard in bragging about supercomputers. You really only hit that peak performance for embarrassingly-parallel problems, but unless you have a specific workload or benchmark to talk about, it's the best you have and is a fairly well-accepted practice in the industry.

On a related note "petaflops" would be a great name for a pet bunny.

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