Supercomputer variant of Kahan quote

Article: Intel's Near-Threshold Voltage Computing and Applications
By: Robert Myers (rbmyersusa.delete@this.gmail.com), October 20, 2012 7:51 am
Room: Moderated Discussions
Emil Briggs (me.delete@this.nowherespam.com) on October 20, 2012 4:52 am wrote:
>
> > I'm constantly being asked to show why I think
> > these machines are
> a waste of money. I'll turn the question around. Will
> > someone please
> explain why, when my desktop could have designed the space
> > shuttle, you
> now need a warehouse full of cabinets to do much less? Your answer
> >
> appears to be a long line of scientists who are unsurprisingly lined up to get
>
> > on the fast track to fill the journals with junk--so they can get
> tenure.
> >
>
> Just for reference. I'm not anonymous and I could care less
> about tenure.
>
That's a good start.

> A lot of supercomputer time gets used for density functional
> calculations. And it has produced valid and useful results that are interesting
> both commercially and from a pure science perspective. Indeed such calculations
> have helped produce that desktop that you talk about since a detailed
> understanding of the physical mechanisms involved is important to improving
> semiconductor processes.
>
I was about two say that, well, you're the first person who hasn't responded to the effect that we are using horrible approximations with these big boxes to get answers with unknown and unknowable accuracy. But then I remembered two things. I have previously been informed by what I take to be a solid state physicist at IBM Watson that they were calculating solid state problems with answers accurate to five digits. Then I also remembered that one of the big open problems of big box computing was that predictions of electron mobility were off by a factor of five. Maybe that problem has been fixed, or maybe it's only necessary to get the sign of an effect correct (if you strain the lattice, the electron mobility improves--only, as Intel discovered, to its dismay, not as much as they had hoped). That you regard these gigantic calculations as a necessary tool of your trade and that you are passionate about it is clear. That I have exhausted the entire extent of my detailed knowledge of the subject is also clear. That's not to say that my understanding of the problem couldn't be improved, only, not in the context of a discussion like the current one. There's also a lot of gigantic cluster time being used to do computer animation and to do inverse scattering for oil exploration, and, at one time, someone in a position to know said that he knew of commercial clusters that had no interest in being on the Top 500 list but that would have blown it away. The difference is that those clusters are being funded with private risk capital, albeit with tax subsidies probably in both cases, and the decision to build them was clearly not driven by egos and academic/national lab politics.

> And there are DFT methods that scale well
> computationally on supercomputers. A bigger limitation is that most DFT methods
> exhibit O(N^3) or worse scaling with the number of atoms being simulated which
> limits things to a few thousand atoms on the current generation of
> supercomputers. To study larger systems (and there are plenty of commercial and
> scientific reasons to want to do so) will require new algorithms.
>
Well, now there are two of you and a paper who appear to believe in perpetual motion.

Robert.
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TopicPosted ByDate
New article: Intel's Near-Threshold ComputingDavid Kanter2012/09/18 12:26 PM
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        Higher SRAM voltage and shared L1David Kanter2012/09/20 12:24 PM
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        Latency and HPC WorkloadsSHK2012/10/08 05:42 AM
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                      Latency and HPC Workloads - Why not SRAM?Robert Myers2012/10/10 10:11 AM
                        Latency and HPC Workloads - Why not SRAM?forestlaughing2012/10/15 08:02 AM
                          Latency and HPC Workloads - Why not SRAM?Robert Myers2012/10/15 09:04 AM
                            Latency and HPC Workloads - Why not SRAM?forestlaughing2012/10/16 09:13 AM
                          Latency and HPC Workloads - Why not SRAM?SHK2012/10/16 08:12 AM
                    Latency and HPC Workloads - Why not SRAM?slacker2012/10/11 01:35 PM
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              Latency and HPC Workloadsanon2012/10/16 08:17 AM
                Latency and HPC WorkloadsRobert Myers2012/10/16 09:56 AM
                  Supercomputer variant of Kahan quotePaul A. Clayton2012/10/16 11:09 AM
                    Supercomputer variant of Kahan quoteanon2012/10/17 01:17 AM
                      Supercomputer variant of Kahan quoteRobert Myers2012/10/17 04:34 AM
                        Supercomputer variant of Kahan quoteanon2012/10/17 05:12 AM
                          Supercomputer variant of Kahan quoteRobert Myers2012/10/17 02:38 PM
                            Supercomputer variant of Kahan quoteanon2012/10/17 05:24 PM
                              Supercomputer variant of Kahan quoteRobert Myers2012/10/17 05:45 PM
                                Supercomputer variant of Kahan quoteanon2012/10/17 05:58 PM
                                Supercomputer variant of Kahan quoteanon2012/10/17 05:58 PM
                                  Supercomputer variant of Kahan quoteRobert Myers2012/10/17 07:14 PM
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                                      Supercomputer variant of Kahan quoteRobert Myers2012/10/18 09:47 AM
                                        Supercomputer variant of Kahan quoteanon2012/10/19 02:34 AM
                                          Supercomputer variant of Kahan quoteanon2012/10/19 04:47 AM
                                          Supercomputer variant of Kahan quoteRobert Myers2012/10/19 03:14 PM
                        Supercomputer variant of Kahan quoteMichael S2012/10/17 06:56 PM
                          Supercomputer variant of Kahan quoteanon2012/10/17 09:02 PM
                            Supercomputer variant of Kahan quoteRobert Myers2012/10/18 01:29 PM
                              Supercomputer variant of Kahan quoteanon2012/10/19 02:27 AM
                                Supercomputer variant of Kahan quoteRobert Myers2012/10/19 07:24 AM
                                  Supercomputer variant of Kahan quoteanon2012/10/19 08:00 AM
                                    Supercomputer variant of Kahan quoteRobert Myers2012/10/19 09:28 AM
                                      Supercomputer variant of Kahan quoteanon2012/10/19 10:27 AM
                              Supercomputer variant of Kahan quoteforestlaughing2012/10/19 10:26 AM
                                Supercomputer variant of Kahan quoteRobert Myers2012/10/19 07:04 PM
                                  Supercomputer variant of Kahan quoteEmil Briggs2012/10/20 04:52 AM
                                    Supercomputer variant of Kahan quoteRobert Myers2012/10/20 07:51 AM
                                      Supercomputer variant of Kahan quoteEmil Briggs2012/10/20 08:33 AM
                                        Supercomputer variant of Kahan quoteEmil Briggs2012/10/20 08:34 AM
                                          Supercomputer variant of Kahan quoteRobert Myers2012/10/20 09:35 AM
                                            Supercomputer variant of Kahan quoteEmil Briggs2012/10/20 10:04 AM
                                              Supercomputer variant of Kahan quoteRobert Myers2012/10/20 11:23 AM
                  Latency and HPC Workloadsanon2012/10/16 06:48 PM
                    Latency and HPC Workloadsforestlaughing2012/10/19 11:43 AM
              Latency and HPC Workloadsforestlaughing2012/10/19 09:38 AM
                Latency and HPC WorkloadsRobert Myers2012/10/19 11:40 AM
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