Raspberry Pi's GPU double the performance of iPhone 4S | Hacker News Reader

Raspberry Pi's GPU double the performance of iPhone 4S

eurogamer.net

93 pointsindy59 comments

Not really embarrassing, no one is comparing the power consumption. Apple could easily go to a more powerful GPU if their battery power allowed them. But I think the current 4S GPU is the one that fits for the current battery technology.

I wonder when mobile devices are going to contain FPGAs. They are often a factor of 100x power/performance better than CPUs/GPUs.

Can you provide some examples where an FPGA provides such performance gains over a modern CPU and GPU combo?

Microsoft Research has some papers on this, for example:

Where’s the Beef? Why FPGAs Are So Fast -- http://research.microsoft.com/pubs/70636/tr-2008-130.pdf

BLAS Comparison on FPGA, CPU and GPU -- http://research.microsoft.com/pubs/130834/ISVLSI_FINAL.pdf

"Results show that FPGAs offer comparable performance as well as 2.7 to 293 times better energy efﬁciency for the test cases that we implemented on all three platforms."

Here's a talk about compiling legacy C/C++ code to FPGAs. With a couple of modifications to the code they claim 100x-300x performance/watt improvement in various benchmarks.

slides: http://msrvideo.vo.msecnd.net/rmcvideos/103696/dl/103696.pdf

video: http://research.microsoft.com/apps/video/default.aspx?id=103...

For example they have a Black Scholes simulation that runs 30x faster and uses 6W of power instead of 68W. That's >300x power efficiency.

Where are you getting those numbers? My experience is quite the opposite. FPGA devices are usually physically large as well.

FPGAs are typically 5-20x worse in power consumption and max speed over a dedicated ASIC with the same logic. That is the price you pay for flexibility of being able to change your design at the drop of a hat.

For now, they are the low volume option (<1-10m units) if you need special interfaces. If all you are doing is number crunching a Gpgu would likely be a more effective option.

While superb for power and performance, the problem with ASICs is that you can't embed an ASIC fab in your mobile phone ;) On the other hand, doing number crunching on a GPU will quickly burn your your battery. FPGAs seem like the ideal middle ground.

Yes and no. I would say that GPUs are the middle ground between traditional serial CPUs and truly parallel FPGAs.

FPGAs are not a silver bullet. If you can express your design using a GPGPU instruction set, then by all means please use that. Its going to be more efficient by an order of magnitude, from power consumption and especially cost.

High end FPGAs can easily run in the $30k for a single unit range (this is what NVidia is going to buy to simulate their latest design in hardware, its not likely going to end up in a shipping product). They are also relative power hogs. Their strength lies in highly concurrent systems, especially around data streaming from disparate interfaces to other interfaces, when you can't put enough I/O bandwidth into an existing processing solution.

GPUs are good at processing and will floor an FPGA there. They are relatively terrible at I/O.

A sentence «and should double iPhone 4S performance across a range of content» is a really authoritative benchmark I suppose...

Wow, that makes this thing a lot more interesting to me, if true. So many designs these days pair monster CPUs with underpowered GPUs it's almost embarrassing (especially as Apple continues to show that powerful GPUs are important for a good user experience). The 256 MB of RAM will be very constraining for any app trying to use all that power, though.

Personally I think the fairly low amount of memory is good and works well with their motive - to promote computer science education. If it had more, you could easily chuck massive frameworks and whatnot at it, but as there's not as much RAM then hopefully people learning with it will have to work a little closer to the bare metal. I'm sure things to make Raspberry Pi work 'easier' will arrive - and that's not necessarily a bad thing - but at least they'll be more constrained.

>"The 256 MB of RAM will be very constraining for any app trying to use all that power, though."

My Archos 101 has 256MB RAM and runs Android suprisingly well. It only does 720p video playback though; full specs http://www.archos.com/products/ta/archos_101it/specs.html?co.... I'm not going to lie, it does tend to lag a bit; wonder how easy upgrading the RAM will be on the RPi.

The RasberryPi is using a BCM2835 SoC that has the RAM on the die. Basically not upgradeable without swapping out the whole chip.

http://en.wikipedia.org/wiki/Raspberry_Pi

And as a consumer (or a company that is not a "Broadcom partner") you can't buy the BCM2835 in any model so even if you could desolder the BGA you couldn't buy any replacement (or build your own boards).

The RAM isn't on the die, it is in a package that gets stacked on top of the SoC package. Still not going to be a simple upgrade though.

Sounds just like the Archos RAM limitation.

The PlayStation 3 has 256 MB of RAM and seems to do ok, as games like Uncharted and God of War show.

It does mean you'll need to be more careful and considerate of how you use that memory though (and admittedly, on a console like a PS3 the OS takes up much, much less space).

Actually it has 512MB split into two pools for CPU and GPU.

The PS3 has 256 MB system RAM and 256 MB dedicated video RAM. So it has twice as much RAM as the Raspberry Pi.

I'm aware of that, does the Raspberry Pi not have separate video ram? If not, that is my mistake - I didn't look closely and made an assumption. If it has a shared block of RAM (like the Xbox 360 Xenon, which has 512mb shared) then that is a significant difference - but still plenty to work wonders with.

But does the Raspberry Pi run on a battery?

The iPhone is highly optimized for mobile use. Both in hardware and software. Can the same be said about this chipset that the Raspberry Pi uses?

If not then the comparison is not very fair.

yea according to their site you can run it on 4 AA cells. Can you buy an IPhone for $25? http://www.raspberrypi.org/faqs

I think it requires about 5w of power so yes. In fact I'm planning on getting a micro usb solar opwer pack to use with it if I can get my hands on a board.

That is pretty cool. You can't buy an iPhone for $25 but you also cannot buy a Raspberry Pi for $25 that has WiFi, 3G, BlueTooth a display, 64GB of flash and 512MB of memory :-)

Anyway, I look really forward getting my hands on an RP.

Yea I was looking at the video of it running XBMC. Thinking of running it as a media center

I can go out and buy an iPhone 4S today. Can you buy a Raspberry Pi at any price right now?

"It's better because it's available now" isn't an incredibly appealing argument when the price different is around $500.

The ARM11 cpu is too old, I wish they used at least a Cortex-A8. ARM11 has a virtually addressed cache with aliasing issues that requires all sorts of hacks in linux kernel, it will require old compiler flags and lacks other ARMv7 features. It's the cpu from 2005. I wonder what the price difference would be if they used an A8.

There are some similar cool open hardware projects sponsored by TI. They have better specs, although their prices are quite a bit higher. I don't know if it is because they do lower volumes, the chips cost more, or price just wasn't as much a concern when they were designed.

The beagleboard-xm has an A8, 4 usb ports, and 512 ram for $150, the related beaglebone has arduino like pins and an A8 for $80, and the pandaboard has an A9, 1gb ram, and wifi for $180.

Thanks, didn't know about these.

#education

I am interested to know what other folks think of the potential to build low cost PCs using Raspberry Pi (RPi) for education in India & the developing world.

I am curious to know what other people think of OLPC XO3 vs RPi vs Aakash (the Indian govt.'s low cost tablet)

OLPC http://news.bbc.co.uk/2/hi/technology/8428147.stm http://asia.cnet.com/what-can-we-learn-from-the-olpc-xo-3-0-...

Aakash Ubislate7 http://blogs.wsj.com/speakeasy/2012/01/08/the-inside-story-o...

1. Raspberry Pi(RPi) requires monitor + mouse +k/b while XO3 is self-contained. 2. RPi is more geared to be a lab machine or a home pc while XO3 is more of a personal device.

3. From a pedagogical viewpoint, IMHO, i think younger kids should not have a digital device 24x7 as they could possibly get "addicted" to it . It is more important to impart a sense of curiosity(scientific temper) & hunger for learning, & having an XO3 might hamper kids' social activities - going outdoors & playing with other kids, being fit, taking part in sports.

So i feel younger kids could be exposed to low-cost computers( made of a RPi) in school, which are low cost & encourage tinkering (open source, simple inexpensive hw) while older (say high school kids can get their own personal XO3.

#4. From an Indian perspective, i wish the Indian govt scraps the crappy Aakash tablet in favour of the XO3.

http://phonemantra.com/2012/01/olpc-india-head-rips-into-aak...

The vast majority of schools in India are run by the govt & most govt. schools dont have a computer lab or the computers:students ratio is abysmal. The RPi could be an excellent, low-cost way to create computer labs in all govt schools, colleges & vocational institutions.

#5. Internet connectivity

http://laptop.org/en/laptop/hardware/specs.shtml http://www.raspberrypi.org/faqs http://www.akashtablet.com/

The XO3 comes with 802.11b/g & most importantly 802.11s(mesh networking) & the concept of school servers, so kids can download learning content even if access to the larger public Internet is not available.

Aakash has GPRS( much slower) & RPi supports wired ethernet & USB WiFi dongles.

Exciting times ahead for sure & would love to hear what other folks think

cheers

p.s. Detailed interview with Eben Upton, RPi's executive director (free registration required)

http://www.gamesindustry.biz/articles/digitalfoundry-inside-...

This is just a linkbait title. "XXX compared to YYY Apple product" is a guaranteed click. Too bad they don't actually compare XXX to YYY...

shame the BCM2835 won't be open sourced anytime soon...

So far as I can tell, this significantly limits the hack value of the Raspberry Pi. Sure, it runs Linux... whatever version was current when it first shipped. Considering Ubuntu and Fedora both ship new releases every six months, a year and a half or two years into the future and what you can do with the Raspberry Pi will be limited to what outdated binary packages you can find, or what software you're prepared to compile yourself on a tiny embedded processor.

I guess $25 isn't exactly a high price to pay for six months to a year of messing about, but it seems a sad fate for an otherwise remarkable piece of hardware.

I think you are too pessimistic on it's lifetime. Firstly, the foundation will likely continue to update the software. Most of the patches they made to the kernel are going to be submitted upstream. Even if the foundation doesn't do it, it can be maintained by the community. It's not infeasible to maintain a fork, although the work will increase with time. Even if it becomes stuck on an older kernel version, it's still not very difficult to run a distribution on top of that, since the userspace-kernel interface is very stable.

The community can't maintain the patches, thanks to Broadcom's policy of not releasing documentation unless you commit to ordering a hundred trillion parts or are employed by them (as the Raspberry Pi folks are).

If the point of this thing is to promote computer science education, then it's already dead. Remember, not everything happens in userspace. For example, there are advanced operating systems courses out there that are focused very closely on the low-level side or are based on non-GPL-compatible operating systems where they can't simply lift stuff out of Linux.

It's nobody's loss but Broadcom's: the educators will go for platforms like BeagleBone instead (which, although more than double the price, is still cheap), the students will have the benefit of well-documented hardware, and TI will be happy that many of those students who grow up to work in the embedded space will be specifying TI (rather than Broadcom) SoCs.

Whilst I would certainly agree it would be nice for the chip to be open-sourced, saying that it means the Pi is 'already dead' is ridiculous hyperbole.

The Raspberry Pi is designed for computer science education, but it's designed primarily for Children, not University Students. If you're at the point of running 'Advanced Operating Systems' courses then you can find whatever you need, but 12 year olds aren't likely to be doing that.

What they folks at Rasberry Pi are trying to do is encourage people who've never coded before to start writing programs. If they can write simple userspace linux programs (I'm talking text adventures and the like) that's what's important. The device isn't intended to replace ultra-hackable low level devices, it's just a cheap PC that children can tinker with without their parents yelling at them if they break the family PC.

The Rasberry Pi is anything but dead.

They absolutely don't need special hardware to start programming.

I'm sure I'm not alone in saying that my first exposure to coding was when I typed "10 PRINT BUTT 20 GOTO 10" into BBC BASIC. I didn't need anything more than the computer I had at school. The modern-day equivalent - typing "python" into the terminal - isn't much different, and still a lot easier and cheaper than getting something to run on an external Linux board.

This IS today's version of the BBC Micro. AFAIK, the BBC Micro was a cheap design to encourage computer education since regular PCs were very expensive.

I too cut my teeth on a BBC Micro. My school had ~20 of them. If they'd bought PCs, they would have had maybe 5?

The Raspberry Pi will do the same thing today, especially in poor countries which don't have computers as a matter of course in their schools.

You're talking from an overly Western-centric perspective when you say that typing "python" is cheaper than the RPI.

The world has 7 billion people, many of whom live in poor countries. At $35 with the ability to use a regular TV as a console, this thing is well within the reach of poor person even in a poor country like India to buy as a splurge for his kid who he's told my their teacher is bright.

I, for one, think this is going to be revolutionary.

PS: I also plan to use it for some home automation projects. It can run off of batteries (!!!!!), and is a plain old GNU/Linux distro. How cool is that.

The BBC Micro was actually quite expensive compared to the other micros of the time. (I don't think the IBM PC was ever considered a "micro", and other micros were probably more capable anyway.) If I remember correctly, the goal was not to produce a design that would compete mostly on cost but rather one that was British and would do the flashy stuff the BBC wanted to show on their computing series.

I agree that the Raspberry Pi will be revolutionary, not because it will rejuvenate computer science teaching, but simply rather because it's a cheap computer.

> I agree that the Raspberry Pi will be revolutionary, not because it will rejuvenate computer science teaching, but simply rather because it's a cheap computer.

Yep. It looks we were mostly in agreement then! :)

Looks like Mali will be the first ARM graphics core to get a free driver http://www.fosdem.org/2012/schedule/event/mali

I don't care about the GPU, but I'm glad to see XBMC running on the thing.

Next up, I want to see some Ubuntu Pi edition, and perhaps even some ChromeOS fork.

My hope is to be able to attach that to the back of a monitor/TV and get a usable browsing and movie watching machine.

Does anyone know if Raspberry Pi has an education / grant program? I'd like to present this to my high school (Small alternative Technical School) and I'm sure they'd love a curriculum that they could review.

Little confused here. Has the Pi project changed from "low-cost education computer for the masses" into "iOS-killing mobile game platform"?

I suspect this[x] is just a way to bring attention to the Broadcom chip that powers the RPi

[x] i mean the article, not the Pi project itself

Does the iPhone 4S actually use a Tegra 2? Everything I've read indicated it used a PowerVR GPU, just like every other iPhone, not a Tegra 2. The article seems fundamentally misguided and incorrect if this is the case.

http://www.anandtech.com/show/4951/iphone-4s-preliminary-ben... says SGX543MP2.

I think the author is saying that the Broadcom GPU outperforms both the Tegra 2 (used in Android devices & netbooks) and the iPhone4S's GPU.

(edit: fixed typo)

Why do you think the author says iPhone 4S uses a Tegra 2? He doesn't say that.

I'm curious, though, is it really a fully open source computer? How does that work when it uses an ARM chip? Or does the open source part refer only to the OS? As soon as ARM replaces ARM11 with Cortex A7 or whatever, we should ask them to open source ARM11.

The ARM chip is not open source, and probably won't be at release either.

I'd say its more closed source than open. The schematic is not released, the chip is a Broadcom ARM (not even for sale to the public), the GPU runs a binary closed blob. Even the boot sequence involves closed source binary "magic".

It runs linux. That's open. The rest, not so much. Its still awesome. It just is what it is.

It can decode and output a 1080p signal. What more do you need from a GPU? :)

Did anybody read the article? There is no demo or measurement, the manufacturer is promising, in an interview, that the SoC should perform like that.

Also, it's pretty confusing, mixing statements about Tegra 2 and iPhone 4S, which are quite different beasts.

It would certainly be impressive, but I'd rather wait for at least a demo, if not proper benchmarks, before throwing the party.

It seems to me that they're comparing a USB powered device to a battery powered device.

The iPhone runs its GPU in a particular way, and its GPU was chosen based on the fact that the iPhone needs to have its battery last all day.

However the Raspberry can draw a continuous 1A without rest, because it effectively has an infinite battery.

So, sure, you can put a larger GPU in a device like that.

* yawn * Let me know when I can freaking buy one! I'm sick of having to use their VM to develop my software, damn it!

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