[HN Gopher] Superconducting Microprocessors? Turns Out They're U... ___________________________________________________________________ Superconducting Microprocessors? Turns Out They're Ultra-Efficient Author : f00zz Score : 212 points Date : 2021-01-13 17:21 UTC (5 hours ago) (HTM) web link (spectrum.ieee.org) (TXT) w3m dump (spectrum.ieee.org) | Symmetry wrote: | Hmm, I wonder what the feature size is and whether they'd have a | good story about storage at commensurate low power usage? | px43 wrote: | It'll be interesting to see if the cryptocurrency mining industry | will help subsidize this work, since their primary edge is | power/performance. | | During stable price periods, the power/performance of | cryptocurrency miners runs right up to the edge of profitability, | so someone who can come in at 20% under that would have a | _SIGNIFICANT_ advantage. | wmf wrote: | _In this paper, we study the use of superconducting technology | to build an accelerator for SHA-256 engines commonly used in | Bitcoin mining applications. We show that merely porting | existing CMOS-based accelerator to superconducting technology | provides 10.6X improvement in energy efficiency._ | https://arxiv.org/abs/1902.04641 | reasonabl_human wrote: | Looks like the admit it's not scalable and only applies to | workloads that are compute heavy, but a 46x increase over | cmos when redesigning with an eye for superconducting env | optimizations | Badfood wrote: | Cost / hash. If power is free they don't care about power | adolph wrote: | / time. Time is immutable cost. | agumonkey wrote: | If something like that happens it will have far reaching | consequences IMO. I'm not pro blockchain.. but the energy cost | is important and it goes away significantly people will just | pile 10x harder on it. | inglor_cz wrote: | Nice, but requires 10 K temperature - not very practical. | | Once this can be done at the temperature of liquid nitrogen, that | will be a true revolution. The difference in cost of producing | liquid nitrogen and liquid helium is enormous. | | Alternatively, such servers could be theoretically stored in the | permanently shaded craters of the lunar South Pole, but at the | cost of massive ping. | gnulinux wrote: | If the throughput is fast enough 3+3=6 seconds latency doesn't | really sound _that_ bad. There are websites with that kind of | lag. You can 't use to build a chat app, but you can use it as | a cloud for general computing. | mindvirus wrote: | Fun aside I learned about recently: we don't actually know if | the speed of light is the same in all directions. So it could | be 5+1=6 seconds or some other split. | | https://en.m.wikipedia.org/wiki/One-way_speed_of_light | faeyanpiraat wrote: | There is a Veritasium video really fun to watch which | exmplains with examples why you cannot measure one way | speed of light: https://www.youtube.com/watch?v=pTn6Ewhb27k | inglor_cz wrote: | Yes, for general computing, that would be feasible. | reasonabl_human wrote: | I wouldn't want to be on call when something breaks on the | moon.... | | Astronaut DRIs? | inglor_cz wrote: | "Oh no, we bricked a lunar computer! Go grab your pressure | suit, Mike! Back in a week, darling... Tell your mother I | won't be attending her birthday party." | juancampa wrote: | > The difference in cost of producing liquid nitrogen and | liquid helium is enormous. | | Quick google search yields: $3.50 for 1L of He vs $0.30 for 1L | of H2. So roughly 10 times more expensive. | inglor_cz wrote: | Nitrogen is N2, though. Liquid nitrogen is cheaper than | liquid hydrogen. | | I was able to find "1 gallon of liquid nitrogen costs just | $0.5 in the storage tank". That would be about $0.12 per 1L | of N2. | monopoledance wrote: | Edit: Didn't read the OP carefully... Am idiot. Anyway, | maybe someone reads something new to them. | | Nitrogen won't get you below 10degK, tho. It's solid below | 63degK (-210degC). | | You know things are getting expensive, when superconductors | are rated "high temperature", when they can be cooled with | LN2... | | Helium (He2) is _practically finite, as we can't get it | from the atmosphere in significant amounts (I think fusion | reactor may be a source in the future), and it's critically | important for medical imaging (each MRI 35k$/year) and | research. You also can really store it long term, which | means there are limits to retrieval/recycling, too. I | sincerely hope we won't start blowing it away for porn and | Instagram. | tedsanders wrote: | That price is more than a decade out of date. Helium has been | about 10x that the past half decade. I used to pay about | $3,000 per 100L dewar a few years ago. Sounds like that price | was still common in 2020: https://physicstoday.scitation.org/ | do/10.1063/PT.6.2.2020060... | | Plus, liquid helium is produced as a byproduct of some | natural gas extraction. If you needed volumes beyond that | production, which seems likely if you wanted to switch the | world's data centers to it, you'd be stuck condensing it from | the atmosphere, which is far more expensive than collecting | it from natural gas. I haven't done the math. I'm curious if | someone else has. | mdturnerphys wrote: | That's the cost for one-time use of the helium. If you're | running a liquefier the cost is much lower, since you're | recycling the helium, but it still "costs" ~400W to cool 1W | at 4K. | faeyanpiraat wrote: | I'm no physicist, but wouldn't you need some kind of medium to | efficiently transfer the heat away? | | On the moon you have no atmosphere to do it with radiators with | fans, so I gues you would have to make huge radiators which | simply emit the heat away as infrared radiation? | rini17 wrote: | Doubt if 80x difference would make it attractive. If it were | 8000x then maybe. | | And that only if you use the soil for cooling, which is non- | renewable resource. If you use radiators, then you can put them | on a satellite instead with much lower ping. | zelienople wrote: | The other strategy that is ultra-efficient is to stop using the | net to sell hoards of useless crap that will break the day after | the warranty expires and cannot be repaired. | | That would save money on the computing power as well as the | mining, transportation of raw materials, refining, transportation | of refined materials, manufacturing, transportation of finished | goods and the whole retail chain. | | Unless we achieve room-temperature semiconducting processors, | this will only benefit data centres, most of whose power is used | to sell stuff. Does anyone actually think that the savings will | be passed on to the consumer or that business won't immediately | eat up the savings by using eighty times more processing power? | | Hey, now we can do eighty times more marketing for the same | price! | jkaptur wrote: | Couldn't you say this about virtually any hardware improvement? | the8472 wrote: | > We use a logic primitive called the adiabatic quantum-flux- | parametron (AQFP), which has a switching energy of 1.4 zJ per JJ | when driven by a four-phase 5-GHz sinusoidal ac-clockat 4.2 K. | | The landauer limit at 4.2K is 4.019x10^-23 J (joules). So this is | only a factor of 38x away from the landauer limit. | dcposch wrote: | > adiabatic quantum-flux-parametron | | https://youtube.com/watch?v=BBqIlBs51M8 | pgt wrote: | I'm curious about how the Landauer limit relates to | Bremermann's Limit: | https://en.wikipedia.org/wiki/Bremermann%27s_limit | | Admittedely, I haven't done much reading, but I see it is a | linked page from Bremermann's Limit: | https://en.wikipedia.org/wiki/Landauer%27s_principle | freeqaz wrote: | Mind expanding on this a bit more? What is that that limit and | how does it relate to the clock speed? | the8472 wrote: | https://en.wikipedia.org/wiki/Landauer%27s_principle | | Note that the gates themselves used here are reversible, so | the limit shouldn't apply to them. But the circuits built | from them them aren't reversible as far as I can see in the | paper, so it would still apply to the overall computation. | Enginerrrd wrote: | It's not about clock speed per se. It's about the lowest | possible energy expenditure to erase one bit of information | (or irreversibly destroy it by performing a logical | operation). The principle comes about from reasoning about | entropy loss in said situations. There's a hypothesized | fundamental connection between information and entropy | manifest in physical law. The idea is that if you destroy one | possible state of a system, you have reduced the entropy of | that system, so the 2nd law of thermodynamics implies that | you must increase the entropy of the universe somewhere else | by at least that amount. This can be used to say how much | energy the process must take as soon as you choose a | particular temperature. | | This applies to any irreversible computation. | | IMO, The fact that it's only 38x the minimum is MIND BLOWING. | jcims wrote: | Is there an idea of entropic potential | energy/gradient/pressure? Could you differentiate encrypted | data from noise by testing how much energy it requires to | flip a bit? | kmeisthax wrote: | Only if you were measuring a system with access to the | key material and doing something with the plaintext, in | which case this would be a side-channel attack (and an | already-studied one). The whole point of encryption is | that the data output is indistinguishable from noise | without knowing the key. | Raidion wrote: | No, because the energy of the system isn't related to the | order of the underlying data, it's related to the changes | that happen to the underlying data. If you have 5 bits | and flip 3, it takes the same energy regardless of if the | 5 bits have meaning or not. This is speaking in terms of | physics. There obviously could be some sort of practical | side channel attack based on error checking times if this | was an actual processor. | ajuc wrote: | > IMO, The fact that it's only 38x the minimum is MIND | BLOWING. | | It's like if someone made a car that drives at 1/38th the | light speed. | yazaddaruvala wrote: | For anyone too lazy to math, its a car that can go: | | 28.4 million km per hour (i.e. 17.6 million miles per | hour) | | I wonder how much that speeding ticket would cost. | | Disclaimer: Assuming the one-way speed of light is 300k | km/s | rbanffy wrote: | > I wonder how much that speeding ticket would cost. | | I once got one for going at about 3x the speed limit | (very nice road in Brazil, broad daylight, nobody in | sight, short run, and very unfortunate radar gun | positioning). The policeman was impressed and joked that | he would like to, but couldn't give me 3 speeding tickets | instead of one. | faeyanpiraat wrote: | This comment took effort and adds to the discussion; | what's with the downvotes? | TheRealNGenius wrote: | No need to assume when we can define ;p | bananabreakfast wrote: | I think they were alluding to the fact that it is | impossible to measure the one-way speed of light, and | even the definition is an assumption based on the two-way | speed | wmf wrote: | Interesting tradeoff: | | _AQFP logic operates adiabatically which limits the clock rate | to around 10 GHz in order to remain in the adiabatic regime. The | SFQ logic families are non-adiabatic, which means they are | capable of running at extremely fast clock rates as high as 770 | GHz at the cost of much higher switching energy._ | jcfrei wrote: | Does superconductivity remove or reduce the limit on die size? | undersuit wrote: | I'm making a naive guess here. No, superconducting transistors | are probably harder to create than non super conducting | transistors so the limits on die size from defects are even | more pronounced and superconducting doesn't change the speed of | light for electrons on the chip so it doesn't change the timing | issues arising from large dies. | akiselev wrote: | The limits on die size for the competitive consumer chip | market are nothing like that of the B2B market. Largest chip | ever made was over 40,000 mm^2 [1] compared to Intel's 10900K | at ~205 mm^2. In production mainframe chips like IBM's Z15s | are on the order of 700mm^2. The fab process has a lot of | levers so very low defect rates are possible but not at the | scale of a consumer CPU. | | [1] https://techcrunch.com/2019/08/19/the-five-technical- | challen... | | Edit: I assume a supercoducting microprocessor would use a | strategy similar to the AI monolith in [1]. Just fuse off and | route around errors on a contiguous wafer and distribute the | computation to exploit the dark zones for heat dissipation. | qayxc wrote: | If implemented using switches based on the Josephson effect | like here, then no. | | The thickness of the required insulating barrier presents a | hard lower limit to the structure size. | | The actual value of that limit depends on the material used and | the particular implementation of the Josephson junction, of | which there seems to be quite a few. | | So the limit depends on how thin the barrier can be made. | sliken wrote: | Can't imagine why it would, but the lack of heat makes a 3D cpu | much more feasible. So you could take 20 die, make 20 layers, | and get radically more transistors per volume. | fastball wrote: | Seems like it would be much harder to keep a stacked CPU | superconducting as heat dissipation would be more difficult. | emayljames wrote: | Could a design with gaps between layers, but still | connected as one not mitigate that though?. | gibbonsrcool wrote: | Maybe I'm misunderstanding but since this 3D CPU would be | superconducting, it would conduct electricity without | resistance and therefore not generate any heat while in | use. | fastball wrote: | The adiabatic (reversible) computations themselves would | be zero-loss, but in order to actually read the result of | your computation you need to waste heat. | faeyanpiraat wrote: | Maybe there are parts which are not superconducting? Like | impurities in the material. So even though the generated | heat is like 0.01% of the original, some heat is still | generated. | sliken wrote: | Presumably 80x less power including cooling means more than | 80x less power not including cooling. | | I'd think that should be enough to get quite a few layers, | sure maybe some minimal space between layers for cooling, | but radically less than the non-superconducting designs. | laurent92 wrote: | This could explain the extreme push to the Cloud, for example | with Atlassian who discontinues its Server products entirely, and | only keeps Data Center or Cloud versions. It behaves as if | personal computing or server rooms in companies won't be a thing | in 2025. | hikerclimb wrote: | Hopefully this doesn't work | nicoburns wrote: | Huh, this seemed a bit too good to be true on first reading. But | given that the limits on computing power tend to thermal, and | that a superconducting computer presumably wouldn't produce any | heat at all, it does kind of make sense. | ska wrote: | The system as a whole will produce heat, but less. | nicoburns wrote: | True, but usually the problem is removing the heat from the | chip, not the total amount of heat produced. If the heat is | mostly produced by the cooling system then that problem all | but goes away. | ska wrote: | Not really at data centre scale. Heat directly in the CPU | is a limiting factor on how fast an individual chip can go, | and at the board level is an issue of getting heat away | from the CPU somehow. | | But that heat has to go somewhere. When you have rooms full | of them the power and cooling issues become key in a way | that doesn't matter when it's just a PC in your room. | mensetmanusman wrote: | Any entropy reduction activity in one area automatically | means a lot more heat is added somewhere else :) (2nd law) | klysm wrote: | Until you account for the energy required to get it that cold | thatcherc wrote: | Subtitle from the link: | | > The 2.5 GHz prototype uses 80 times less energy than its | semiconductor counterpart, _even accounting for cooling_ | | (emphasis mine) | amelius wrote: | Yeah, but only at datacenter scales. | | > Since the MANA microprocessor requires liquid helium-level | temperatures, it's better suited for large-scale computing | infrastructures like data centers and supercomputers, where | cryogenic cooling systems could be used. | ernst_klim wrote: | So great for big computing centres and such? CERN and other | should be happy with it. | lallysingh wrote: | DC scale is great. Most stuff runs in a DC. What's wrong | about requiring DC scale? | alkylketone wrote: | I'd be curious what the energy savings are like at smaller | scales -- 80x at data center scales, but how about for a | smaller machine, like a PC with phase cooling? | nullc wrote: | I would expect the cooling to have a scaling advantage-- | heat gain is proportional to surface area, but the mount | of superconducting mojo you can use is proportional to | volume so it should be more energy efficient to build | larger devices. | thatcherc wrote: | The authors' power comparison is outlined in Section VI | of their paper [0] (page 11-12). You might be able to | figure out some intermediate scalings from that! | | [0] - https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arn | umber=929... | lallysingh wrote: | This sounds perfect for space. It's cold in space, power is at a | premium, and it can be tough getting rid of heat. | vincnetas wrote: | Its a bit cold in space. But actually its really difficult to | cool down things in space as there is nothing around you to | transfer heat to. | TOMDM wrote: | I'm ignorant of the specific physics, but what if you got it | cold before you sent it into a vacuum, and then shielded it | from external radiation? | | Surely due to the massively reduced power usage it would be | easier to keep it cool relative to traditional compute | fastball wrote: | The problem is that the act of computation is generating | heat, so you can't just insulate your superconducting CPU, | you need a way to dissipate the heat it _must_ generate | (this applies to all irreversible computations). This is | difficult, because the only way to dissipate heat in space | is radiation (with conduction usually acting as a | middleman), which is constrained by the surface area of | your radiator. | | So no, it probably wouldn't be any easier in space. | akiselev wrote: | Ideally this server farm would attach to a giant rock | somewhere in a stable orbit and drill heat exchange pipes | deep into the rock, like how we do for geothermal energy | here on earth but in reverse. This whole exercise would | require a nuclear reactor to be feasible both | economically and engineering wise. | cbozeman wrote: | Mass Effect taught me this. | | I miss old school BioWare. | fastball wrote: | Was this a plot point in ME? I don't remember that. | cbozeman wrote: | It was one of the "scan a planet" type side mission | things. | | I just remember that that particular planet didn't have | much of an atmosphere, so it wasn't good for dumping | excess heat from ships. | rytill wrote: | I have heard this elsewhere, but when I looked into it, it | seems like it's not that big of a challenge compared to the | other difficulties of space. More of just a consideration | that has to be part of the design. See: | https://en.m.wikipedia.org/wiki/Spacecraft_thermal_control | | Can anyone give an expert opinion on the difficulty of | cooling in space? | benibela wrote: | In Sundiver by David Brin they put all the heat in a laser, | so they can beam it away from their craft | jetrink wrote: | Is it possible to do this without violating the second law | of thermodynamics? | titanomachy wrote: | Definitely possible to put _some_ of the heat into a | laser. It 's simple to turn a temperature gradient into | an electrical potential [0], and if you use that | electricity to power a laser it will convert away some of | the hat. | | [0] https://en.wikipedia.org/wiki/Thermocouple | m4rtink wrote: | AFAIK it is not and IIRC the author even mentioned it | somewhere afterwards, possibly in the next book. | reasonabl_human wrote: | I can't think of a reason it would violate any basic | physical laws. Use a peltier cooler in reverse as the | transducer from heat to electricity, apply to an | appropriately spec'd solid state laser. Surely the devil | is in the details somewhere.. | vincnetas wrote: | Peltier generator would need somwhere to transfer the | heat to. But there is nothing around. | superkuh wrote: | Sure. But how efficient are they once you include the power used | to keep them cold enough to superconduct? I doubt that they're | even as efficient as a normal microprocessor would be. | SirYandi wrote: | "But even when taking this cooling overhead into account," says | Ayala, "The AQFP is still about 80 times more energy-efficient | when compared to the state-of-the-art semiconductor electronic | device, [such as] 7-nm FinFET, available today." | b0rsuk wrote: | Given the cooling requirements, I suppose it would create | completely impassable rift between datacenter computing and other | kinds. Imagine how programming and operating systems might look | in a world where processing power is 80x cheaper. | | Considering that "data centers alone consume 2% of world's | enegy", I think it's worth it. | hacknat wrote: | > Imagine how programming and operating systems might look in a | world where processing power is 80x cheaper. | | Just wait 10 years? | Jweb_Guru wrote: | Not sure if you noticed, but Moore's Law died quite awhile | ago now. | mcosta wrote: | For single thread performance. | anfilt wrote: | Moore's laws has nothing to do with how fast a chip is. | It deals with how many transistors you can fit in a given | area. | | This can equate to a faster chip because you now can do | more at once. However, we hit the frequency limits a | while ago for silicon. Particularly, parasitic | capacitance is a huge limiting factor. A capacitor will | start to act like a short circuit the faster your clock | is. | | Moore's law has a little more life, although the rate | seems to have slowed. However, at the end of the day it | can't go one forever you can only make something so | small. One gets to a point they have so few atoms to | constructing something useful becomes impossible. Like | current transistors are finFETs because the third | dimension gives them more atoms to reduce leakage | current, compared to the relatively planar designs on | older process nodes. However, these finFets still take up | less area on a die. | xwdv wrote: | As processing power cheapens, programmers will settle for lazy | and inefficient code for everyday consumer applications. It | will be easier to be a programmer, because you can get away | with writing shitty code. So wages will fall and the prestige | of being a software developer wanes. The jobs requiring truly | elite skill and understanding will dwindle and face fierce | competition for their high pay. | | Before this happens, I recommend having your exit strategy for | the industry, living off whatever profits you made working as a | developer during the early 21st century. | gameswithgo wrote: | did you write this in 1980? | no_flags wrote: | Processing power has cheapened exponentially for the last 50 | years (Moore's law). I am skeptical that a continuation of | this trend will drive a fall in wages. | | In my own experience performance optimization is an important | but infrequent part of my job. There are other skills an | elite programmer brings to the table like the ability to | build a mental model of a complex system and reason about it. | If downward pressure on wages occurs I think it will be for | another reason. | Enginerrrd wrote: | I think in general you are right, however, there will | certainly be sectors where it will be a lot easier to just | throw it at a wall of computation than pay someone to think | about it. | | But architecting complex systems so that they are | maintainable, scalable, and adaptable... there's not gonna | be enough cheap computation to solve that problem and omit | top talent for a long time. | Fronzie wrote: | Energy cost and thermal cooling place restrictions on the | computations. C++, with all it flaws, stays in use because it | does give control over performance trade-offs. | vlovich123 wrote: | I'm less pessimistic. Even if CPUs are 10x faster than they | are, that still opens up more opportunities than what can be | "absorbed" by less efficient coding/masses. There will always | be demands for eking out more of the available | processing/compute power and doing so will always be a | difficult task. For example, today you can edit large scale | videos in real-time and view various movie-quality SFX | applied real-time on a consumer desktop. More computing power | = more ability to do things cheaply that were in | feasible/impossible before. You're limited by your | imagination more than anything. | | What's truly more of a threat is AI-aided programming if that | ever becomes a thing. Again, I'm not worried. The gap between | telling an AI "do something that makes me $1 billion dollars" | and "write a function that has properties x/y/s" or "do this | large refactor for me and we'll work together on any | ambiguous cases", is enormous. So you'll always have a job - | you'll just be able to do things you couldn't in the past | (it's questionable whether an AI can be built that generates | programs from vague/poorly defined specs from product or even | that generates those specs in the first place. | | As an obvious counter example to your theory, we have CPUs | that are probably 10000x more powerful than in 1980 (actually | more if you consider they have processing technologies that | didn't even exist back then like GPUs and SIMD). The software | industry is far larger and devs make more individually. | | Technically SIMDs and GPUs existed back then but in a much | more immature form, being more powerful, cheaper and | widespread today than what was available in the 80s. | layoutIfNeeded wrote: | >Imagine how programming and operating systems might look in a | world where processing power is 80x cheaper. | | So like 2009 compared to 2021? Based on that, I'd say even more | inefficient webshit. | Jweb_Guru wrote: | Processing power is not 80x cheaper now than it was in 2009 | unless you can do all your computation on a GPU. | systemvoltage wrote: | Javascript emulator in Javascript! | lkbm wrote: | Gary Bernhardt's presentation on the "history" of | Javascript from 1995 to 2035 is hilarious and seems like | something you'd enjoy: | https://www.destroyallsoftware.com/talks/the-birth-and- | death... | | It takes things way beyond simply "emulating Javascript in | Javascript", yet is presented so well that you barely | notice the transition from current (2014) reality to a | comically absurd future. | dmingod666 wrote: | Do you mean the "eval()" function? | jnsie wrote: | Anyone remember Java 3D? 'cause I'm imagining Java 3D! | vidanay wrote: | Java 11D(tm) It goes to eleven! | sago wrote: | I don't understand your reference. It seems negative, but | it's hard imho to go down on the success of Minecraft. Or | am I misunderstanding you? | zinekeller wrote: | Minecraft (obviously the Java edition) actually uses some | native libraries (LWJGL) so I don't know if Minecraft is | a good comparison. | AnIdiotOnTheNet wrote: | Considering that many modern interfaces are somehow less | responsive than ones written over 20 years ago _even when | running those programs on period hardware_ , I feel certain | that you are right. | xxpor wrote: | But it probably took 80x less time to develop said | software. | layoutIfNeeded wrote: | I'd doubt that. | api wrote: | I don't see an impassible rift. Probably at first, but | supercooling something very small is something that could | certainly be productized if there is demand for it. | | I can see demand in areas like graphics. Imagine real-time | raytracing at 8K at 100+ FPS with <10ms latency. | adamredwoods wrote: | Cyptocurrency demands. | twobitshifter wrote: | Jevons Paradox would predict that we'll end up using even more | energy on computing. | ffhhj wrote: | > Imagine how programming and operating systems might look in a | world where processing power is 80x cheaper. | | UI's will have physically based rendering and interaction. | mailslot wrote: | It'll all be wasted. When gasoline prices plummet, everyone | buys 8mpg SUVs. If power & performance gets cheaper, it'll be | wasted. Blockchain in your refrigerator. | whatshisface wrote: | Solid state physics begets both cryogenic technology and | cryocooling technology. I wouldn't write off the possibility of | making an extremely small cryocooler quite yet. Maybe a pile of | solid state heat pumps could do it. | jessriedel wrote: | This is true, but the fact that heat absorption scales with | the surface area is pretty brutal for tiny cooled objects. | Calloutman wrote: | Not really. You just have the whole package instead a | vacuum casing. | jessriedel wrote: | Really. Vacuum casing is not even close to sufficient to | set heat absorption to zero because of thermal radiation. | | And you can't just make the walls reflective once the | cold object gets smaller than the wavelength of the | radiation. The colder the object, the longer that | wavelength. | Calloutman wrote: | The way it works is that the entire assembly is in a | vacuum. It kinda has to be as any gas which touches it | will instantly condense to it or freeze to it. You then | have a dual cryostat of liquid helium and liquid nitrogen | cooling down the assembly (within the vacuum). The helium | and nitrogen cryostat also have a vacuum shield. The | nitrogen (liquid at 77K) is a sacraficial coolant which | is far cheaper than liquid helium (liquid at 4K) that you | need to get to these temperatures. Your're right that | thermal radiation is an issue so you have to be careful | with the placement of any windows or mirrors around the | device. | | Souce. I have a PhD in physics where I used equipment | cooled to 4K. | jessriedel wrote: | Great, then we both have physics PhDs, and you'll know | that none of that equipment has, or easily could be, | sufficiently miniaturized, which is the topic of | discussion ("extremely small cryocooler"). You can't put | nested closed dewers of liquid nitrogen and helium on a | O(1 mm^2) microchip, and the reason is exactly what I | said: it will warm up too fast. | extropy wrote: | What's wrong with attaching said microchip to a piece of | copper for increased size? Genuinely curious. | | To be useful in a data center you could cool a slab of | copper the size of a fridge and surface mount thousands | of chips on it. | jessriedel wrote: | The topic is cooling small objects so that personal | electronics (e.g., your phone) can compete with | datacenters. Cold at scale (i.e., in datacenters) is | comparatively easy. | Calloutman wrote: | Ah, you're totally right. I misread the OP. Sorry. | jessriedel wrote: | No problem :) | whatshisface wrote: | Don't forget about thermal radiation. | whatshisface wrote: | Heat conduction also scales with thermal conductivity, | which is another thing that advances in solid state can | bring us. | jessriedel wrote: | This doesn't change the fact that, for any degree of heat | conductivity achieved smaller packages will be hard to | keep cold than large ones. | whatshisface wrote: | It also doesn't change the fact that smaller devices are | harder to put wires on - but they're both polynomial | scaling factors that other polynomial scaling paradigms | could cancel out. | jessriedel wrote: | The topic of discussion is datacenter vs. an extremely | small cryocooler. What is the other polynomial scaling | paradigm that would cancel out the datacenter's | advantage? | xvedejas wrote: | It seems likely that the more efficient our processors become, | the larger share of the world's energy we'll devote to them | [0]. Not that that's necessarily a bad thing, if we're getting | more than proportionally more utility out of the processors, | but I worry about that too [1]. | | [0] https://en.wikipedia.org/wiki/Jevons_paradox | | [1] https://en.wikipedia.org/wiki/Wirth%27s_law | carlmr wrote: | >Not that that's necessarily a bad thing, if we're getting | more than proportionally more utility out of the processors | | The trend seems to be that we get only a little bit of extra | utility out of a lot of extra hardware performance. | | When the developer upgrades their PC it's easier for them to | not notice performance issues. This creates the situation | where every few years you need to buy a new PC to do the | things you always did. | philsnow wrote: | > The trend seems to be that we get only a little bit of | extra utility out of a lot of extra hardware performance. | | "hardware giveth, and software taketh away" | _0ffh wrote: | Nice! Another (slightly more pessimistic) one is | "Software gets slower faster than hardware gets faster". | ganzuul wrote: | So by dropping support for old CPUs, the Linux kernel burns | a bridge. That conversation makes more sense now. | thebean11 wrote: | If the developer doesn't notice the performance issues, | maybe they move on to the next thing more quickly and get | more done overall? | | I'm not sure if that's the case, but it may be we aren't | looking for utility in the right places. | avmich wrote: | I'm sure a lot of developers upgrade their PCs (they were | called workstations at a time) because of material problems | - keyboards getting mechanically worse, and laptops can't | easily get keyboard fixed, screens getting dead pixels, | sockets getting loose, hard-to-find batteries getting less | charge, and maybe some electronics degradation. | | Another reason is upgrades to software, which maintain | general bloat, and which is hard to control; new hardware | is easier. That's however is very noticeable. | | On top of that, just "better" hardware - say, in a decade | one can have significantly better screen, more cores and | memory, faster storage; makes easier for large software | tasks (video transcoding, big rebuilds of whole toolchains | and apps, compute-hungry apps like ML...) | ryukafalz wrote: | >laptops can't easily get keyboard fixed | | This is a frustrating part of recent laptops, but it | doesn't have to be this way - my X230's keyboard is | removable with a few screws. | akiselev wrote: | Is that the case for our highly centralized clouds? No | one's putting a liquid nitrogen cooled desktop in their | office so this type of hardware would be owned by companies | who are financially incentivized to drive down the overhead | costs of commoditized functionality like networking, data | replication and storage, etc. leaving just inefficient | developer logic which I assume is high value enough to | justify it. | root-z wrote: | It's quite common in the cloud industry to trade hardware | for shorter development cycle these days too. I think | that's because there is still very high growth in the | sector and companies all want to be the first offering | feature X. As cloud services become more mature I expect | people will be more cost sensitive. Though when that will | happen I cannot say. | winter_blue wrote: | > Not that that's necessarily a bad thing, if we're getting | more than proportionally more utility out of the processors, | but I worry about that too | | I have two points to comment on this matter. | | Point 1: The only reason I would worry or be concerned about | it is if we are using terribly-inefficient programming | languages. There are languages (that need not be named) which | are either 3x, 4x, 5x, 10x, or even 40x more inefficient than | a language that has a performant JIT, or that targets native | code. (Even JIT languages like JavaScript as still a lot less | efficient because of dynamic typing. Also, in some popular | complied-to-native languages, programmers tend to less | efficient data structures, which results in lower performance | as well.) | | Point 2: If the inefficiency arises out of _more actual | computation_ being done, that 's a different story, and I AM | TOTALLY A-OK with it. For instance, if Adobe Creative Suite | uses a lot more CPU (and GPU) _in general_ even though it 's | written in C++, that is likely because it's providing more | functionality. I think even a 10% improvement in overall user | experience and general functionality is worth increased | computation. (For example, using ML to augment everything is | wonderful, and we should be happy to expend more processing | power for it.) | moosebear847 wrote: | In the future, I don't see why there's anything holding us | back from splitting a bunch of atoms and having tons of cheap | energy. | VanillaCafe wrote: | If it ever gets to home computing, it will get to data center | computing far sooner. What does a world look like where data | center computing is roughly 100x cheaper than home computing? | valine wrote: | Not much would change I imagine. For most tasks consumers care | about low latency trumps raw compute power. | cbozeman wrote: | Dumb terminals everywhere. A huge upgrade of high-speed | infrastructure across the US since everyone will need high | throughput and low latency. Subscriptions will arise first, as | people fucking love predictable monthly revenue - and by people | I mean vulture capitalists, and to a lesser degree, risk-averse | entrepreneurs (which is almost an oxymoron...), both of whom | you can see I hold in low regard. Get ready for a "$39.99 mo. | Office Productivity / Streaming / Web browsing" package", a | "$59.99 PrO gAmEr package", and God knows what other kinds of | disgusting segmentation. | | Someone, somewhere, will adopt a Ting-type model where you pay | for your compute per cycle, or per trillion cycles or whatever, | with a small connection fee per month. It'll be broken down | into some kind of easy-to-understand gibberish bullshit for the | normies. | | In short, it'll create another circle of Hell for everyone - at | least initially. | f1refly wrote: | I really appreciate your pessimistic worldview, keep it up! | cbozeman wrote: | I basically just base my worldview on the fact that | everyone is ultimately self-serving and selfish. Hasn't | failed me yet. :) | gpm wrote: | Flexible dumb terminals everywhere. But we already have this | with things like google stadia. Fast internet becomes more | important. Tricks like vs code remote extensions to do realtime | rendering locally but bulk compute (compiling in the case) on | the server become more common. I don't think any of this | results in radical changes from current technology. | tiborsaas wrote: | You could play video games on server farms and stream the | output to your TV. You just need a $15 controller instead of a | $1500 gaming PC. | | :) | whatshisface wrote: | It will look like the 1970s. | andrelaszlo wrote: | Not a physicist so I'm probably getting different concepts mixed | up, but maybe someone could explain: | | > in principle, energy is not gained or lost from the system | during the computing process | | Landauer's principle (from Wikipedia): | | > any logically irreversible manipulation of information, such as | the erasure of a bit or the merging of two computation paths, | must be accompanied by a corresponding entropy increase in non- | information-bearing degrees of freedom of the information- | processing apparatus or its environment | | Where is this information going, inside of the processor, if it's | not turned into heat? | aqme28 wrote: | I was curious about this too. This chip is using adiabatic | computing, which means your computations are reversible and | therefore don't necessarily generate heat. | | I'm having trouble interpreting what exactly that means though. | patagurbon wrote: | But you have to save lots of undesirable info in order to | maintain the reversibility right? Once you delete that don't | you lose the efficiency gains? | ladberg wrote: | It's still getting turned into heat, just much less of it. The | theoretical entropy increase required to run a computer is WAY | less than current computers (and probably even the one in the | article) generate so there is a lot of room to improve. | abdullahkhalids wrote: | If your computational gates are reversible [1], then in | principle, energy is not converted to heat during the | computational process, only interconverted between other forms. | So, in principle, when you reverse the computation, you recover | the entire energy you input into the system. | | However, in order to read out the output of computation, or to | clear your register to prepare for new computation, you do | generate heat energy and that is Landauer's principle. | | In other words, you can run a reversible computer back and | forth and do as many computations as you want (imagine a | perfect ball bouncing in a frictionless environment), as long | as you don't read out the results of your computation. | | [1] NOT gate is reversible, and you can create reversible | versions of AND and OR by adding some wires to store the input. | tromp wrote: | This microprocessor composed of some 20k Josephson junctions | appears to be pure computational logic. | | In practice it will need to interface to external memory in order | to perform (more) useful work. | | Would there be any problems fashioning memory cells out of | Josephson junctions, so that the power savings can carry over to | the system as a whole? | faeyanpiraat wrote: | If you compare cpu power usage with ram power usage, you'll see | ram is already quite efficient, so even if traditional ram | connected to the said microprocessor cannot be brought under | the magic of this method, it might work. | | (Haven't read the article, or have any expertise in this field, | so I might be wrong) ___________________________________________________________________ (page generated 2021-01-13 23:00 UTC)