itanic

By: anon (anon.delete@this.anon.com), January 3, 2019 3:12 am
Room: Moderated Discussions
Brett (ggtgp.delete@this.yahoo.com) on January 2, 2019 11:41 pm wrote:
> anon (anon.delete@this.anon.com) on January 2, 2019 7:56 pm wrote:
> > rwessel (robertwessel.delete@this.yahoo.com) on January 2, 2019 4:53 pm wrote:
> > > Doug S (foo.delete@this.bar.bar) on January 2, 2019 10:38 am wrote:
> > > > Brett (ggtgp.delete@this.yahoo.com) on January 2, 2019 12:15 am wrote:
> > > > > This is not Itanic, which was always a pack of lies, from every angle you look at the problem.
> > > > > The Mill team does not have billions to chase rainbows, which
> > > > > is the most generous thing you can say Itanic was doing.
> > > >
> > > >
> > > > Remember where Itanium originated - with HP's PA-RISC group 25+ years ago looking beyond where PA-RISC
> > > > needed to go after the obvious 64 bit extension. One of the main ideas behind the original "RISC"
> > > > strategy was that smarter compilers would allow slimming the transistor budget for the things the
> > > > compiler could do, to be used for other things that wouldn't have otherwise been possible.
> > > >
> > > > RISC was a success, so the next logical step to HP's architects was to expect even more out
> > > > of compilers, further slimming the transistor budget (no longer needing to worry about OOE,
> > > > etc.) to be used for other things that wouldn't have otherwise been possible (i.e. wider)
> > > >
> > > > I don't know what evidence existed (in research or whatever) that the "magic compiler" necessary
> > > > to make RISC work was possible before the first RISC, any more than similar evidence existed
> > > > for EPIC's "magic compiler". In hindsight, the latter was obviously a much bigger step than
> > > > the former, and proved to be too much, but I don't see how HP's team could have known that at
> > > > the time. They had no reason to sell a "pack of lies" or "chase rainbows", they were designing
> > > > a successor to PA-RISC, which would only be used if it actually performed better.
> > > >
> > > > Obviously the Itanium engineers will have figured out it WAS infeasible years before Intel actually
> > > > killed it - because Intel didn't want the egg on their face after the heavy promotion and had various
> > > > commitments to it (especially to HP) that meant keeping it alive far longer than it should have been.
> > > > Intel needed to get 64 bit x86 widely avaiable so they had a good story to tell ("wow x86 has scaled
> > > > so much better than expected we really don't need Itanium any longer") to try to save face.
> > >
> > >
> > > The first RISCs were pretty small projects, and weren't intended to change the world like IPF was.
> >
> > This is a pretty vast over simplification, and probably based mostly
> > on marketing and execu speak about the technologies after the fact..
> >
> > People working on RISC research and development were absolutely as passionate and strong
> > believers in the potential and value of what they were working on as the EPIC people. Everyone
> > would have hoped they could help advance the computing industry one way or another.
> >
> > > Had they
> > > failed because of system level issues (like needing magic compilers), they'd have just faded quietly away.
> > > Plus, much of the motivation for RISC was the notion that
> > > compiler were *not* using all the CISC-y stuff in
> > > CPUs, so to a certain extent, RISC was designed to support
> > > what compilers were already clearly capable of using.
> > > There were certainly lapses, and often far too much was
> > > punted to software, especially at the system level.
> > > But the only thing really being assumed about compilers
> > > by the early RISC folks was that it would be compilers,
> > > and not assemblers. After all, the model was basically
> > > a simple, in-order ISA, with a short pipeline. Toss
> > > high clock rates in with the short pipeline, and it would have been hard not to succeed.
> >
> > "Compilers should just be compilers" is vastly understating the technical challenges, but if
> > you don't consider RISC as such a large or risky step as EPIC, that's probably not unreasonable
> > but I don't know that it fundamentally makes EPIC the very different and dishonest.
> >
> > RISC designers saw trends in silicon performance that indicated pipelining
> > would be necessary for logic to take advantage of it reasonably, and that
> > held true for them and the technologies required did turn out to work.
> >
> > EPIC saw silicon trends of things like power density and wire delay etc and projected that OOOE structures
> > would not be able to take advantage of it reasonably and their compiler parallel model would.
> >
> > I don't want to excuse Intel the company handling and marketing of Itanium, or even absolve
> > technical failures, but around the time EPIC was being developed, it was trying to solve
> > real and serious concerns of the time. And some of those concerns have not really been solved
> > ever (single threaded performance), you could say that OOOE has failed less badly.
> >
> > I say this as an OOOE fan, but I think it's too much to criticize EPIC technical people as being dishonest.
> > It's nice that there are significant moon shot efforts like that in industry, although maybe it's harder in
> > some ways to let go of a failing project there than academia where publications are worth a lot more.
>
> The Intel x86 teamS were universal in saying Itanic was not going
> to be faster, beyond that that there was no faster approach.

Whether this is true, what has it got to do with what I wrote?

I never said there was universal acceptance of EPIC. Nor was/is there of RISC. I'm sure many on the x86 teamS also held a strong belief that RISC was not necessary for a high performance CPU either.

>
> Itanic was covered by patents for 20 years and beyond that the arch was too difficult
> and expensive for AMD to clone. Too difficult for Intel as well. ;)

Again, what's your point even if this is true (or unusual -- a CPU company with patents, who could have possibly guessed?) ?

>
> Even after the first two versions were slower than x86 management did not
> care,

"Care" is pretty handwavy, and the statement is basically meaningless.

> the only competition left was Sparc which was also slower than x86.

Incorrect.

> Itanic was the only Intel 64 bit arch and Intel wanted monopoly
> rent instead of duopoly rent.

Intel certainly would have loved to have a proprietary instruction set instead of x86. They also made foolish decisions about Itanium. Certainly with hindsight, but toward the end also outright.

> Period.

Not an argument.

> This explains it all.

For some pretty restrictive values of "all", and loose definitions of "explains it".

>
> > And I actually don't think it was the compiler tech that let
> > down Itanium. You can inline and unroll and parallelize
> > everything but you can't adapt to unpredictable data flow
> > in software anywhere but the most trivial things you
> > can add prefetch or advanced loads. So it was never aiming to solve that major problem in software. Then if
> > the stars had aligned slightly differently making OOOE a little more expensive and allowing some kind of in
> > orderish run ahead implementation to be done efficiently with IA64, things may be different today.
>
>

< Previous Post in ThreadNext Post in Thread >
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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