Yes, I know, the forum is named *Real* World Tech, but I'm thinking that perhaps

By: Domaldel (moris.b.rubeksson.delete@this.gmail.com), January 1, 2019 5:52 pm
Room: Moderated Discussions
Domaldel (moris.b.rubeksson.delete@this.gmail.com) on January 1, 2019 4:44 pm wrote:
> Maynard Handley (name99.delete@this.name99.org) on January 1, 2019 12:17 pm wrote:
> > Simon Farnsworth (simon.delete@this.farnz.org.uk) on January 1, 2019 5:05 am wrote:
> > > Domaldel (moris.b.rubeksson.delete@this.gmail.com) on December 31, 2018 11:40 pm wrote:
> > > > David Hess (davidwhess.delete@this.gmail.com) on December 31, 2018 8:32 pm wrote:
> > > > > Doug S (foo.delete@this.bar.bar) on December 31, 2018 9:26 am wrote:
> > > > > > David Hess (davidwhess.delete@this.gmail.com) on December 30, 2018 6:26 pm wrote:
> > > > > > >
> > > > > > > The die price (size) problem has puzzled me for a while. For thermally limited designs which
> > > > > > > have a die smaller than can be produced, couldn't a higher clock speed be achieved be deliberately
> > > > > > > using a lower transistor density for a lower junction to case thermal resistance at the cost
> > > > > > > of higher power? I do not know of anybody doing it though or at least admitting it.
> > > > > >
> > > > > > What's the cause of hitting that thermal limit, it is a lack of ability to remove heat from a specific sq
> > > > > > mm or few sq mm, or is it the lack of ability to remove heat from the entire package? For the former what
> > > > > > you suggest will work, for the latter you upgrade to water cooling etc. to remove heat more quickly.
> > > > >
> > > > > It is the former which is why thermal management tracks
> > > > > power and temperature of different areas. One thing
> > > > > which would help is better materials for heat spreaders but they are all much more expensive than copper or
> > > > > even silver. A directly attached heat pipe would be ideal
> > > > > but the power density is much greater than a heat
> > > > > pipe will support except in low power applications some of which do use a directly attached heat pipe.
> > > > >
> > > > > I had not considered it before but a lot of the performance gain or rather lack of performance
> > > > > loss with denser processes since integrated temperature sensing was first used comes from monitoring
> > > > > temperature and power at many points instead of the average temperature which explains why so
> > > > > much effort is put into it. It is the peak temperatures and hot spots which matter.
> > > > >
> > > >
> > > > While not really viable for home build systems etc I imagine that you could
> > > > probably deal with a 3D server processors hot spots using a combination of thermal
> > > > planning and a built in cooling system *inside* the processor itself.
> > > >
> > >
> > >
> > > Do you mean something like IBM's ICECool research project? This is where IBM runs a
> > > dielectric fluid through the chip, set up so that the chip boils the fluid internally
> > > (cooling the chip) and it condenses again outside the chip ready to flow back round.
> >
> > The problem with a liquid to gas transition is that you get a huge accompanying volume change.
> > For many purposes that's horribly undesirable. I don't see any pictures in the ICECool article,
> > or actual numbers, but I expect this makes the tech a non-starter outside maybe data centers.
> >
> > More generally what you want is a transition from a very low to a very high entropy state. Liquid to
> > gas is great --- but since the entropy increase DERIVES (mostly) from the volume increase, it's always
> > going to be impractical. What we want is something like maximum entropy change/volume NOT maximum entropy
> > change/mass. There are, of course, dozens of these - changes in magnetic state, changes in crystal
> > structure, Mott transitions - but then we add in all the other constraints. I'm guessing a liquid is
> > more practical than a solid, so most of the transitions that rely on crystal structure are out. Maybe
> > a solid to liquid melting would do the job --- but again the entropy change is just not that large
> > compared to boiling. (Enthalpy of vaporization tends to be about 10x that of fusion).
> > Now there are other ways to slash entropy back and forth. You can use high structure molecules that switch
> > between orientation phases (liquid crystals). You can use
> > chemical reactions. But as far as I can tell these
> > are all lousy numerically compared to the sweet sweet chaos of running around in a much larger volume.
> >
> > You can look at this from a different direction. There are
> > technologies today that generate a large amount of
> > heat in a very small volume. (Eg quantum cascade lasers
> > are generating 20W or more in a volume the size of a
> > small rice grain.) These are cooled not by phase transitions
> > by active cooling -- TE Coolers using Peltier effect.
> > Of course these come with their own headaches -- they're expensive, finicky to mount, and large...
> >
> > And remember WHATEVER you do, all you're doing is moving heat from where it's generated to somewhere
> > else where it can be radiated. You're not actually "eating up" the heat. So what's the radiation plan
> > once the heat gets moved from inside the chip to the chamber where the boiled vapor collects?
> >
> > It's theoretically POSSIBLE that 3D architecture could generate lots of heat deep inside a structure,
> > and that it's advantageous to stream that out of the system as fast as possible using a liquid heat
> > transport medium (basically capillaries running through your 3D chip). Now the figure of merit is
> > not how much heat can be absorbed at a fixed temperature (ie phase change issues); it's how much
> > heat can be moved at a certain speed (so a combination of heat capacity and viscosity).
> > But while this is theoretically possible, that's very different from saying it's likely. It's probably
> > VASTLY more efficient to try to solve this problem via other means first --- better 3D planning, keep the
> > circuits as power efficient as possible, create CVD diamond VIAs to wick heat, things like that...
> >
> > I think the bottom line is that you have to clarify what's the market you have in mind, and so how
> > much hassle can it put up with? But whatever you want, physics is not really on your side :-(
> >
> > - Mainstream is mobile, laptops, NUCs, thin AIOs --- all devices where
> > large volumes to hold gas+radiators, or even a TEC, are not feasible.
> > - Data centers have enough space, but generally aren't interested in paying a lot more (and
> > giving up a fair bit of space) to buy a small amount of additional latency reduction.
> > - FINANCIAL data centers are probably already doing this, but they can just dump their boards in fluorinert
> > or something equally insane and crazy expensive --- nothing special needed in the CPU beyond the ability
> > to function (for at least a month or two before it dies) at the highest voltage you can pump into it; and
> > what they do is mostly decoupled from and has no effect on what the rest of the world is doing.
> >
>
> The discussion came out of the whole eager execution thread to begin with.
> Let's just say that we're *not* talking mobile here. ;-)
>
> But yeah, thanks for your input. =)
>
> I'm not working in the industry, so right now I'm essentially "theorycrafting" trying
> to imagine some ways that a high end processor in the future might need if maximum
> performance is the design goal with priority over all other considerations.
>
> In essence if at every chance where there's a trade off between latency optimization
> and anything else be that power consumption, processor cost or whatever, you consistently
> go for latency optimizations then how would that processor end up looking?
>
> So I'm thinking semi-eager execution (at some point you're forced to turn to specualtion but you
> can minimize the amount of branch misspredictions by increasing the amount of multi-pathing).
>
> And so one and so forth.
>
> Think a design that's not just a few cm square but perhaps the size of a whole wafer *and* 3D (meaning multiple
> wafers pr package) with built in redundancy to cope with flaws during the production, and possibly also quite
> a bit of binning, so perhaps 1 in 200 wafers are accepted as a layer in a say 50 layer design?
>
> I don't know.
> Point is just if you take things to extremes and do everything (non-quantum) that current and near future technology
> is capable of what is possible to achieve with binary technology in terms of latency reductions?
>
> Mind you, with as much of those optimizations as possible being hardware side and
> not compiler side and with the design being general purpose and not an ASIC.
>
> Think a custom made super computer where hand placing individual atomes on tens of thousands of
> wafers is a genuine option if that's required, in other words money is not a concern at all.

Yes, I know, the forum is named Real World Tech, but I'm thinking that perhaps speculating about some fictional possibilities might inspire us a bit and help us come up with something real long term even if it's not directly usefull.

I'd love to make a home brew processor of some kind that's got features not found anywhere else that might still be usefull.
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TopicPosted ByDate
Independent micro threadsBrett2018/12/30 01:55 PM
  Independent micro threadsTravis Downs2018/12/30 04:18 PM
    Independent micro threadsBrett2018/12/30 07:16 PM
      Independent micro threadsTravis Downs2018/12/30 07:34 PM
        Independent micro threadsBrett2018/12/30 07:48 PM
          Independent micro threadsTravis Downs2018/12/30 09:06 PM
            Independent micro threadsBrett2018/12/30 10:57 PM
              Independent micro threadsTravis Downs2018/12/31 12:42 AM
                Independent micro threadsBrett2019/01/01 07:02 PM
                  Independent micro threadsMichael S2019/01/02 02:01 AM
                    Independent micro threadsMaynard Handley2019/01/02 03:29 PM
              Independent micro threadsMontaray Jack2019/01/01 02:12 AM
  Independent micro threadsanon2018/12/30 04:34 PM
  Independent micro threadsPaul A. Clayton2018/12/30 05:15 PM
  Independent micro threadsDavid Hess2018/12/30 06:47 PM
    Independent micro threadsDomaldel2018/12/30 07:06 PM
      Independent micro threadsDavid Hess2018/12/30 07:26 PM
        Independent micro threadsDoug S2018/12/31 10:26 AM
          Independent micro threadsDavid Hess2018/12/31 09:32 PM
            Independent micro threadsDoug S2019/01/01 12:40 AM
              Independent micro threadsDavid Hess2019/01/01 11:41 AM
            Overcomming thermal limits of a high dencity 3D arcitecture (Formerly "Independent micro threads")Domaldel2019/01/01 12:40 AM
              Overcomming thermal limits of a high dencity 3D arcitecture (Formerly "Independent micro threads")Domaldel2019/01/01 12:44 AM
                Overcomming thermal limits of a high dencity 3D arcitecture (Formerly "Independent micro threads")Domaldel2019/01/01 12:49 AM
                  Overcomming thermal limits of a high dencity 3D arcitecture (Formerly "Independent micro threads")Domaldel2019/01/01 12:51 AM
              Overcomming thermal limits of a high dencity 3D arcitecture (Formerly "Independent micro threads")Simon Farnsworth2019/01/01 06:05 AM
                Overcomming thermal limits of a high dencity 3D arcitecture (Formerly "Independent micro threads")Domaldel2019/01/01 08:01 AM
                Overcomming thermal limits of a high dencity 3D arcitecture (Formerly "Independent micro threads")Maynard Handley2019/01/01 01:17 PM
                  Taking things to extremes.Domaldel2019/01/01 05:44 PM
                    Yes, I know, the forum is named *Real* World Tech, but I'm thinking that perhapsDomaldel2019/01/01 05:52 PM
                      Yes, I know, the forum is named *Real* World Tech, but I'm thinking that perhapsMontaray Jack2019/01/02 07:26 AM
                        Yes, I know, the forum is named *Real* World Tech, but I'm thinking that perhapsMontaray Jack2019/01/02 08:21 AM
                    Taking things to extremes.Maynard Handley2019/01/01 06:55 PM
                    Taking things to extremes.Kevin G2019/01/04 08:57 AM
              Overcomming thermal limits of a high dencity 3D arcitecture (Formerly "Independent micro threads")David Hess2019/01/01 11:36 AM
    Independent micro threadsTravis Downs2018/12/30 07:38 PM
    Independent micro threadsBrett2018/12/30 07:41 PM
  Independent micro threadsanon2018/12/30 08:20 PM
    Independent micro threadsBrett2018/12/30 08:51 PM
      Independent micro threadsTravis Downs2018/12/30 09:48 PM
        Mill and Independent micro threadsBrett2019/01/01 07:39 PM
          No. Mill does not get the hit because it does not get the benefit even when correctly predicted.Heikki Kultala2019/01/02 12:29 AM
            No. Mill does not get the hit because it does not get the benefit even when correctly predicted.Brett2019/01/02 01:15 AM
              No. Mill does not get the hit because it does not get the benefit even when correctly predicted.Heikki Kultala2019/01/02 02:22 AM
                No. Mill does not get the hit because it does not get the benefit even when correctly predicted.Brett2019/01/03 01:13 AM
                  "Leaf branch" is not a commonly used termHeikki Kultala2019/01/03 03:48 AM
                    "Leaf branch" is not a commonly used termBrett2019/01/03 04:35 AM
                      You lack parallelism than OoOE givesHeikki Kultala2019/01/03 07:38 AM
                        You lack parallelism than OoOE givesBrett2019/01/04 02:41 AM
                          You lack parallelism than OoOE givesBrett2019/01/04 04:10 PM
                            You lack parallelism than OoOE givesBrett2019/01/05 08:29 PM
                              Mill speculates, more parallelism than OoOE givesBrett2019/01/05 08:31 PM
                                Mill *is* a speculationEric Bron2019/01/06 05:04 AM
                                  Mill *is* a speculationMichael S2019/01/06 05:53 AM
                                    Mill *is* a speculationBrett2019/01/06 09:03 PM
                                  Mill *is* a speculationjuanrga2019/01/06 06:10 AM
                                    probably ~2 (NT)Michael S2019/01/06 06:51 AM
                                  Mill *is* a speculationBrett2019/01/06 01:18 PM
                                    Mill *is* a speculationEric Bron2019/01/06 03:36 PM
                                      Mill *is* a speculationBrett2019/01/06 08:47 PM
                                        Mill *is* a speculationJacob Marley2019/01/06 10:29 PM
                                          Mill *is* a speculationBrett2019/01/07 04:24 AM
                                            Mill *is* a speculationMichael S2019/01/07 05:23 AM
                                            Mill *is* a speculationEric Bron2019/01/07 05:36 AM
                                              Mill *is* a speculationBrett2019/01/07 03:40 PM
                                                Mill *is* a speculationEric Bron2019/01/07 05:32 PM
                                            Mill is something you don't understandHeikki Kultala2019/01/08 04:19 AM
                                              Mill is something you don't understandMichael S2019/01/08 07:44 AM
                                                Itanium and static vs dynamicHeikki Kultala2019/01/09 03:14 AM
                                                  Itanium and static vs dynamicPaul A. Clayton2019/01/09 08:51 AM
                                        Mill *is* a speculationEric Bron2019/01/07 05:27 AM
                                          Mill *is* a speculationEric Bron2019/01/07 06:23 AM
                                      Mill *is* a speculationanon2019/01/07 06:24 AM
                                        Mill *is* a speculationEric Bron2019/01/07 06:52 AM
                                          Mill *is* a speculationanon2019/01/07 08:36 AM
                                            Mill *is* a speculationEric Bron2019/01/07 09:20 AM
                                        Mill *is* a speculationjuanrga2019/01/07 10:22 AM
                                          Mill *is* a speculationanon2019/01/07 01:16 PM
                                        Mill *is* a speculationanon2019/01/07 09:46 PM
                                          Mill *is* a speculationanon2019/01/08 01:56 AM
                                            Mill *is* a speculationanon2019/01/08 03:39 AM
                                              Mill *is* a speculationMichael S2019/01/08 03:52 AM
                                                Mill *is* a speculationanon2019/01/08 10:10 PM
                                                  Wasted width not wasted work.Brett2019/01/09 11:44 AM
                                                    No such thing was declared. (NT)anon2019/01/09 03:41 PM
                                                    Very simple test for new uarch ideassomeone2019/01/10 07:03 AM
                                                      Very simple test for new uarch ideasdmcq2019/01/10 07:21 AM
                                                        Very simple test for new uarch ideasDoug S2019/01/10 10:01 AM
                                                          Very simple test for new uarch ideasDan Fay2019/01/10 01:13 PM
                                                      Very simple test for new uarch ideasanonymous22019/01/10 11:03 AM
                                                        Very simple test for new uarch ideasAlberto2019/01/10 11:32 AM
                                                      Very simple test for new uarch ideasEtienne2019/01/11 03:03 AM
                                                        Very simple test for new uarch ideasFoo_2019/01/11 04:31 AM
                                                          Very simple test for new uarch ideasEtienne2019/01/11 05:51 AM
                                                            Very simple test for new uarch ideasFoo_2019/01/11 05:53 AM
                                                              Very simple test for new uarch ideasdmcq2019/01/11 06:08 AM
                                                              Very simple test for new uarch ideasEtienne2019/01/11 06:13 AM
                                                                Very simple test for new uarch ideasFoo_2019/01/11 06:54 AM
                                                                  Very simple test for new uarch ideasEtienne2019/01/11 07:32 AM
                                                                    Very simple test for new uarch ideasBrett2019/01/11 10:25 AM
                                                                      Very simple test for new uarch ideasMegol2019/01/12 06:29 AM
                                                                        Very simple test for new uarch ideasMichael S2019/01/12 09:21 AM
                                                                          Word salad AI fundamentaliy brokenBrett2019/01/12 01:59 PM
                                                                          Very simple test for new uarch ideasMegol2019/01/13 11:51 AM
                                              Mill *is* a speculationanon2019/01/08 08:50 AM
                                                Mill *is* a speculationEric Bron2019/01/08 09:03 AM
                                                  Mill *is* a speculationanon2019/01/08 09:21 AM
                      "Leaf branch" is not a commonly used termMichael S2019/01/03 07:57 AM
                        "Leaf branch" is not a commonly used termBrett2019/01/04 03:29 AM
                  Calls are not needed for speculation for mill if there are no side effect,and dont help if there areHeikki Kultala2019/01/08 04:28 AM
              No. Mill does not get the hit because it does not get the benefit even when correctly predicted.anon2019/01/02 03:05 AM
              No. Mill does not get the hit because it does not get the benefit even when correctly predicted.Doug S2019/01/02 11:38 AM
                No. Mill does not get the hit because it does not get the benefit even when correctly predicted.rwessel2019/01/02 05:53 PM
                  No. Mill does not get the hit because it does not get the benefit even when correctly predicted.anon2019/01/02 08:56 PM
                    itanicBrett2019/01/03 12:41 AM
                      itanicanon2019/01/03 03:12 AM
                      itanicDavid Hess2019/01/03 08:06 AM
                    No. Mill does not get the hit because it does not get the benefit even when correctly predicted.rwessel2019/01/03 09:18 AM
                      No. Mill does not get the hit because it does not get the benefit even when correctly predicted.anon2019/01/04 05:25 AM
                    Itanium could have been RISC or CISC - same outcomesomeone2019/01/04 07:45 AM
                      Itanium could have been RISC or CISC - same outcomeDoug S2019/01/04 12:39 PM
                        Itanium could have been RISC or CISC - same outcomeJan Olšan2019/01/04 01:58 PM
                          "fluffyRISC" has a namevvid2019/01/04 03:48 PM
                        Itanium could have been RISC or CISC - same outcomeBrett2019/01/04 03:43 PM
                      Itanium could have been RISC or CISC - same outcomeanonymou52019/01/04 12:41 PM
                  No. Mill does not get the hit because it does not get the benefit even when correctly predicted.David Hess2019/01/03 08:15 AM
                No. Mill does not get the hit because it does not get the benefit even when correctly predicted.Maynard Handley2019/01/03 12:24 PM
                  No. Mill does not get the hit because it does not get the benefit even when correctly predicted.Maynard Handley2019/01/03 12:27 PM
                    No. Mill does not get the hit because it does not get the benefit even when correctly predicted.dmcq2019/01/04 01:59 AM
                  EPIC target marketsFoo_2019/01/04 06:29 AM
                    EPIC target marketsDoug S2019/01/04 12:42 PM
                      Lack of future visionDoug S2019/01/04 12:57 PM
                        Lack of future visionBrett2019/01/04 02:59 PM
                          Lack of future visionDoug S2019/01/04 04:25 PM
                            Lack of future visionBrett2019/01/04 05:18 PM
                              Lack of future visionDoug S2019/01/05 12:47 AM
                                Lack of future visionBrett2019/01/05 02:06 PM
                                  Lack of future visiondmcq2019/01/05 02:22 PM
                                  Lack of future visionanon2019/01/05 03:01 PM
                                    Lack of future visionMichael S2019/01/05 04:18 PM
                                      Lack of future visionanon2019/01/05 06:14 PM
                                        Lack of future visionMichael S2019/01/06 02:01 AM
                                          Lack of future visionanon2019/01/06 03:23 AM
                                          Mitch Alsup's MY66000 uses IF-like predication (I think) (NT)Paul A. Clayton2019/01/06 04:54 PM
                                            ??? (NT)Michael S2019/01/07 05:25 AM
                                            88K ? (NT)anonymous22019/01/07 04:20 PM
                                          Modestly expanded response: MY66000 predicate shadowPaul A. Clayton2019/01/07 11:53 AM
                      Thanks for the correction (NT)Foo_2019/01/04 04:31 PM
              No. Mill does not get the hit because it does not get the benefit even when correctly predicted.sdrc2019/01/04 07:36 AM
          Mill and Independent micro threadsMichael S2019/01/02 02:32 AM
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