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ARM Designer Steve Furber On Energy-Efficient Computing
ChelleChelle writes "By now, it has become evident that we are facing an energy problem — while our primary sources of energy are running out, the demand for energy is greatly increasing. In the face of this issue, energy-efficient computing has become a hot topic. For those looking for lessons, who better to ask then Steve Furber, the principal designer of the ARM (Acorn RISC Machine), a prime example of a chip that is simple, low power, and low cost. In this interview, conducted by David Brown of Sun's Solaris Engineering Group, Furber shares some of the lessons and tips on energy-efficient computing that he has learned through working on this and subsequent projects."
That means a portable computer with an ARM processor and a reflective monochrome display big enough to hold normal text pages. In other words an Amazon Kindle DX (separate wired or bluetooth keyboard is fine), but with an open OS that lets me write and run my own programs without having to jailbreak past some DRM crap. Somebody please make something like that? Please??
In the face of this issue energy-efficient computing has become a hot topic
No. That has, and never was the case. The problem is A) Programs now take a lot more CPU usage (compare CPU usage for the same task in Office 2007 and Office 97) B) CPUs are designed primarily to be faster (needed because of point A) C) Battery technology isn't improving as rapidly as the rest of the components.
Look at the Poqet PC of the '80s, it had very aggressive power management which wouldn't work today. Computers have -always- tried to be energy-efficient in the portable sector. And quite honestly, its about the only sector that needs work on energy-efficiency to gain any benefit.
Taxation is legalized theft, no more, no less.
We just need to see Windows support for ARM, and then we'll be well on our way towards it being a widely available option.
And you also mean the porting of thousands and thousands of x86 apps as well? If the ARM version of Windows can't run the apps people want, they aren't going to by an ARM netbook.
(record the uptime with a pen+paper if you want to keep a running total)
Taxation is legalized theft, no more, no less.
http://openinkpot.org/wiki/Hardware
There are a bunch of cheap 'n cheerful Kindle clones that are supported by the openinkpot firmware, if e-ink is your style.
If you need the refresh rates of an LCD, I think you may have a problem. There is the OpenMoko Wikireader which is super low power and pretty cheap; but the screen(although touch sensitive) is a little smaller than what you want and the CPU is more of a microcontroller than what you probably want.
You might also consider going the OLPC route. That gets you a rather nice monochrome screen(with backlight color optional) and, while x86, it is a ~1watt embedded Geode, not too power hungry. That one is also by far the most "normal computer" like of the bunch(i.e. no having to code around super slow refresh rates, and running basically standard linux, rather than building binaries for some microcontroller).
Nothing exactly like what you want(that I know of); but there are some approaches...
Because there is almost no market for it. Lets see here
A) Monochrome displays (other than E-ink) are generally considered to be low-tech, cheap, pieces of junk. Look at how well monochrome TVs are selling... Yes, it does ease strain on eyes and increase readability, but has the other side of making most of... well anything unpleasant to look at other than text.
B) It will be expensive. Amazon can afford to produce the Kindle at-cost or even with a bit of a loss because they will gain sales in e-books and such. Even if they sell it at a profit they still can buy parts in bulk and make them cheaper than a product with a run of only ~1,000 units or less.
C) There aren't enough apps. What apps would make sense to port to this device? Lynx? Most other things would need more CPU power (making it non-energy efficient) or a colour screen.
Really, other than you, this wouldn't appeal to a large enough audience of people. Best thing to do would be to jailbreak an existing e-reader, its simply a bad business decision to make a product with almost no market.
Taxation is legalized theft, no more, no less.
efficient. I mean if you consider any unit of computation vs energy expended. I bet my current desktop computer would compare from a computation point of view to a super computer from the late 80's. (GFLOP to GFLOP) However my current computer pulls about 300W, I'm pretty sure that's alot better than any super computer from the 80's that would compare to it.
Did you know 80 to 90% of the moderators on slashdot wouldn't recognize a troll even if one dragged them under a bridge.
http://en.wikipedia.org/wiki/Comparison_of_e-book_readers
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Bit shift instead of multiply by powers of two
I'd think a decent compiler should do that automagically, no?
Sent from my PDP-11
Look up "Energy Return on Energy Invested".
Saudi oil has been 100:1.
Shale... 5:1 maybe, 3:1.
http://en.wikipedia.org/wiki/Oil_shale
When they really start using shale, you know the shit is really hitting the fan.
And no matter how much is left (quoted in the reserve figures as recoverable), could be a trillion trillion barrels, nobody is going to bother trying to get it out when it takes a unit of energy in to get a unit of energy out.
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Use floats where doubles aren't necessary
That assumes that floats are more energy efficient than doubles. Not necessarily true on architectures that have hardware floating point and save energy by omitting the float portion. They convert the float to double, do the math, then convert back. Check your architecture!
On my Intel Core 2, the execution speed is different by about 0.06% between float and double (edge to double). Can't speak to power consumption though. On my Intel Atom 230, the floats are faster by 0.4%. That's almost certainly saving power, but not a lot.
I'm a big fan of arm. I have two of those!
Maybe he means you'll save the energy the compiler would spend to optimize a multiply into a bit shift :-)
And you also mean the porting of thousands and thousands of x86 apps as well?
But most people don't USE thousands and thousands of apps. Or even hundreds of apps. Most people don't even use dozens of apps. You got your web browser and your IM client (maybe), (maybe) an email client, a DVD player, and I bet that's it for the vast majority of computer users outside of work. IM & email clients can be handled by the browser. Seriously - Chrome OS or Android running on a nice 1-2gHz dual-core ARM beast with hardware accelerated HD video w/ 4GB of memory is probably all that most people need at home, as long as it's got a decent screen, keyboard and mouse, they're set.
Download your Android apps, of which there *are* thousands (though many different versions of a much smaller number of TYPES of applications) for expanding into more obscure things. Most of which would be games, of course.
I'd like to see Chrome OS & Android merge sooner rather than later. Absolutely no point in having these be separate projects - with the rise of 'superphones,' there's not that much difference in horsepower anymore, and one platform target is better than two from a developer standpoint (usually).
IMO, anyway. :)
I'm hoping the day when I can take my dual-core 1+ gHz superphone out of my pocket, put it in a dock at home to get a big screen, real keyboard and mouse and true broadband home connection. Shouldn't be more than a year away. C'mon, Sprint, with the Supersonic! I'll fire up the beastly machine when I need to run Photoshop or whatever, but most of the time at home, my computer use is watching TV/movies/websurfing/email.
You haven't actually ported any non-trivial app, have you?
Nasty, dirty shitty coal. Coal power should just be illegal already.
Nuke, wind, solar, natural gas all are alternatives with far less pollution and co2 release.
Probably from a reliable source. The chip that he designed was the Acorn RISC Machine. When ARM was spun out as a joint venture with Apple, it was renamed. Advanced RISC Machines is a backronym intended to keep the same initials but remove the Acorn branding (which Apple didn't want).
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Actually, you're only half right. On ARM, there is typically no double hardware, so you get a very slow path for 64-bit floating point arithmetic. On your Core 2, it's more complicated. The x87 unit only supports 80-bit floating point values. This means that any float or double will be sign-extended when it is loaded into a register. You gain a bit better cache usage from using 32-bit floats, but that's it.
No both, however, if you compile with SSE then you will be using a vector for all floating point operations. With floats, the compiler can pack concurrent operations on four of them into a single instruction, with doubles it can only pack two. I'm not sure about the Atom, but I vaguely remember that it splits SSE ops in half, so you really do two 64-bit operations. Either way, you can do twice as many float operations in the same power envelope, as long as your code is suited to vectorisation.
Modern compilers prefer to target SSE instead of x87, because register allocation with x87 is painful. Most operations only work between the top two registers in the 'stack' so you need a lot of register-register copies in a typical bit of x87 code (which burns i-cache too). This is one of the main reasons why you see a performance improvement in x86-64; if you have a 64-bit chip you can guarantee the presence of SSE, so the compiler will always use SSE instead of x87 when compiling 64-bit code. If you're someone like Apple and don't support pre-SSE chips, you can also do this and get the same benefit in 32-bit mode.
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I not so sure, it was not all that long ago most of us who even had a computer were working on an 80x86 or 80x88 with a 512k of memory, connected to a 80x25 character monocrome display, with no network interface, and primary storage consisting of a box next to the unit filled with 360k floppy disks.
You know what we were like pigs in s**t happy too. I have cell phone, not a facy smart phone. I just use it I don't think about it. I charge it Sunday night before I go to bed and I talk and text on it as much as I want to all week long. The batter never goes flat over that time frame.
I had a smart phone for a little while. It could not even stand by all day. I had to go back because I was afraid I might miss SMS alerts from critial systems because the things battery went flat.
I would be very happy with a device that was inexpensive enough to leave on the back seat of my car for weeks on end that would be just there if I needed it and ready to go. Something that could connect to the internet wireless-ly and run lynx and those kinda of apps would be just perfect, even if the screen refresh was slow an e-ink based. Things like e-mail would be very doable as well. We don't live in the same world that 80x86 lived in. There is all kind of infrastructure around, let the POP or IMAP server do the thinking, just add a command like TXTPLZ to the protocols that would instruct the server to render messages sent in other formats out as plain characters. Get send html no problem
becomes 13 and 10. Hell use libcacca to render images as ascii art.
The software you need to write and run on the device could do allot by simply offloading the thinking to the oh lord dare I say it? cloud...
Repeal the 17th Amendment TODAY! Also Please Read http://www.gnu.org/philosophy/right-to-read.html
I worked at Acorn in the early 80's and knew Steve Furber, but it's amusing to think that most of the Slashdot crowd probably wasn't even born then. I assume the average age here nowadays must be college age or thereabouts.
Not surprising they don't know what ARM originally stood for.
For less than the cost of the financial stimulus package, or the Iraq war for that matter, the US could produce almost all it's electricity with solar thermal plants with present level technology (and the cost for plants would probably be quartered by the time you are done because of economies of scale, so it would cost far less). Hugely reducing electricity costs in the US would probably do more for the economy than just about anything else the money could be spend on.
As a European I'm envious ... the US really has it all, virtual dead deserts with round the year sunlight, a reserve currency which gives you nearly limitless free money to spend on these kinds of projects, and hell quite a nice supply of oil reserves as well ... it's frankly a miracle how your politicians manage to fuck that kind of potential up.
Run PowerTOP on Linux (and use a tickless kernel, of course). There are some offenders, but most of those background services aren't using any power. As long as the processes are sleeping most of the time and don't wake up often (once every few seconds at most), they aren't going to increase your power usage.
There are a few slightly annoying ones (ntp tends to wake up once per second, and I think mysql wakes up twice per second), but most of the crap comes from poorly-written GUI apps that poll for stuff or feel the need to wake up tens or hundreds of times per second. Bad user preferences also don't help (hint: anything that's moving on the screen at any sort of framerate while the computer is otherwise idle is going to massively increase power usage over a truly quiescent CPU).