Slashdot Mirror
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??
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.
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
Deleted
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
I'm a big fan of arm. I have two of those!
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).
I am TheRaven on Soylent News
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.
I am TheRaven on Soylent News
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.