Dear Santa, thank you for the dolls and pencils and the fish. It's Easter now, so I hope I didn't wake you but... honest, it is an emergency. There's a crack in my wall. Aunt Sharon says it's just an ordinary crack, but I know its not cause at night there's voices so... please please can you send someone to fix it? Or a policeman, or... Back in a moment. Thank you Santa.
Thursday, January 01
The Landauer Bound
We all know that while Moore's Law is still holding - just - Dennard Scaling failed in the early 2000s. Clock speeds have remained unchanged for more than a decade.
What most don't realise is how fast we are approaching the thermodynamic limits of computational efficiency. If Koomey's Law holds, we will reach perfect efficiency - the dreaded Landauer Bound - by 2048.
Mark that date in your calendars, boys and girls! 2048 is the year it all ends.
1
The reason clock rates leveled off was that we ran screeching into Planck's Constant.
Posted by: Steven Den Beste at Thursday, January 01 2015 11:57 PM (+rSRq)
2
Or at least, Planck's Constant's Little Friends. As I understand it (I don't even play a quantum physicist on television) it's essentially a long list of second- and third-order effects of quantum uncertainty.
So, for example, as transistors get smaller, you have to reduce the switching voltage so that you don't damage them over time. A lower voltage also means less current leakage with narrow insulators. But a lower switching voltage directly leads to slower switching. So although the smaller transistor can switch faster, if you actually do that, all your painfully-earned gains go out the window.
There's a review up on Anandtech right now where they overclock an 8-core CPU. Getting it from the default clock (which varies between 3 and 3.5GHz depending on core temperature) up to 4GHz uses an extra 70W of power and raises the core temperature from 54C to 65C, which is into the realm of diminishing returns but not awful. But getting it to 4.4GHz - just another 10% - requires a further 120W of power (on a 140W CPU) and pushes the temperature to a scorching 93C.
Posted by: Pixy Misa at Friday, January 02 2015 12:41 AM (PiXy!)
Thing is, if the transistor is smaller and the voltages are lower, then you get more quantum leakage ("tunneling") across the junction. At a certain point there's as much leakage when the transister is "off" as current flow when it is "on", and the device isn't useful any longer.
The only solution is to increase the voltage, with all the bad things that leads to.
Posted by: Steven Den Beste at Friday, January 02 2015 03:21 AM (+rSRq)
4I don't even play a quantum physicist on television
If need be, I can get a real one for you. Assuming he's not jetting to some overseas conference or another, that is. Or swing dancing. Or both
Posted by: Wonderduck at Friday, January 02 2015 11:18 AM (jGQR+)
5
Another limit we're coming close to is the size of a silicon atom. As strange as it might seem, FETs these days are so small that you can count the atoms in the junction.
Posted by: Steven Den Beste at Friday, January 02 2015 05:01 PM (+rSRq)
6
Maybe reversible computing will arrive in time to save us. (I recall reading a paper about these ideas back in the late 90s, hmm... I think it was something by Tom Knight, which he called adiabatic circuits)
Posted by: Kayle at Saturday, January 03 2015 06:53 AM (W8clb)
Posted by: Pixy Misa at
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Sunday, December 21
Left Right Out
So, that #illridewithyou fuss.
The promoters of this - thing - unthinkingly accused Australians of being violent bigots. They took advantage of an unfolding tragedy to push their opinions.
Rather than looking at the problems we were actually facing, they trotted out an imaginary problem, and offered anonymous support for an imaginary solution.
1
I really feel sorry for his wife. There's no reason to believe she had anything to do with his crime(s) and now she's stuck forever being the widow of a crazy monster.
Posted by: Steven Den Beste at Saturday, December 20 2014 05:11 AM (+rSRq)
2
This is not clear from the news items, but his widow has been charged with the murder of his ex-wife, who was stabbed seventeen times, set on fire, and dumped in a stairwell.
Posted by: Pixy Misa at Saturday, December 20 2014 10:51 AM (PiXy!)
"Muslim leader Keysar Trad said the imam of the Lakemba mosque "doesn’t want a bar of himâ€. But he added that according to Islamic law, no Muslim can be denied a holy funeral unless they renounced their religion prior to death."
Would it be in poor taste to point out that he is certainly welcome to demand a Muslim funeral if he so desires? It doesn't seem like anyone else is likely to ask for one for him, so a denial per se isn't likely to be a problem.
Posted by: RickC at Saturday, December 20 2014 02:02 PM (0a7VZ)
I keep getting a feeling of deja vu on the character designs. The art style is like something I've seen before, I'm just sure of it. (It's probably an homage, like the way the Fairy Tail character art style resembles One Piece.) But I cannot for the life of me remember what NnT's art style reminds me of! It's frustrating.
Posted by: Steven Den Beste at Friday, December 19 2014 04:45 AM (+rSRq)
