6 ms·

Please excuse my ignorance in this area, I was just wondering - why does it matter so much who has the biggest and baddest supercomputer? Shouldn't that which w

by bjd2385 10y ago

Please excuse my ignorance in this area, I was just wondering - why does it matter so much who has the biggest and baddest supercomputer? Shouldn't that which we process on them matter more? A while back I recall reading rumors that China didn't even know what to process on their Tianhe-2. That kind of makes a supercomputer look like a pile of hardware, no matter how well it's organized or engraved.

dibanez 10y ago
Its essentially a matter of realistic benchmark acceptance. Right now machines are compared by how well they run this benchmark called LINPACK, which has been criticized for being non-representative of real science codes. As mentioned here [1], China's new system only achieved 0.3% of its peak flops on a slightly more realistic benchmark, HPCG. [1] http://www.hpcwire.com/2016/06/19/china-125-petaflops-sunway/ http://www.hpcwire.com/2016/06/19/china-125-petaflops-sunway...
- sanxiyn 10y ago
  While Sunway TaihuLight has weak HPCG performance, 0.3% number should be understood in context. Tianhe-2 (#2 system) scores 1.1%, and Titan (#3, US #1 system) scores 1.2% for HPCG. So Sunway TaihuLight is 3~4x worse for HPCG compared to other top systems. Note that K computer (#5 system, Japan) scores 4.9% for HPCG. So Tianhe-2 and Titan are again 4x worse for HPCG compared to systems which score best for HPCG.
  - bhouston 10y ago
    Why does the Sunway TaihuLight have bad HPCG performance? I suspect it has to do with memory bandwidth needed to serve 260C on the same chip?
    - sanxiyn 10y ago
      Yes, it's memory and interconnect. I don't think it's as simple as LINPACK bad, HPCG good. LINPACK is representative for some workloads, when compute dominates. HPCG aims to balance compute and memory. There is Graph500, if memory dominates for your workload. By the way, K computer is #1 in Graph500.
      - ams6110 10y ago
        http://www.graph500.org/ http://www.graph500.org/ The interconnect on the Sunway TaihuLight seems to be standard Infiniband, from reading other articles about the system.
- aab0 10y ago
  I was wondering about third-party benchmarks. As far as I know, the Top500 is pure self-report, and this is a big national-prestige thing...
bluedino 10y ago
>> rumors that China didn't even know what to process on their Tianhe-2. Kind of reminds me of when we heard a rumor than a rival ISP had bought a handful of Sun servers (in the year 2000). We thought they had tends of thousands of customers, figured they would be launching DSL, figured that had thousands of web hosting customers... Turns out they got some weird grant so they spent the cash on those, otherwise they would have lost the money. They went out of business a year later and we kept chugging along with our Pentium III servers.
- tluyben2 10y ago
  This happened a lot with Sun around that time; I bought 10 E450s for fun from one of the hosters who did exactly that and since then went bankrupt. Great, unbreakable machines.
  - ams6110 10y ago
    Bubble dot-com companies rich with VC cash did the same thing. Built massively overprovisioned data centers with expensive Sun servers (because Sun == Internet at that time) and never actually had the traffic to justify even a fraction of it.
bhouston 10y ago
> A while back I recall reading rumors that China didn't even know what to process on their Tianhe-2. That kind of makes a supercomputer look like a pile of hardware, no matter how well it's organized or engraved. There are enough high quality universites in China to make use of it. I can not imagine this is true. There may have not been one big algorithm that it was built for, but university researchers always have stuff to compute.
jonbaer 10y ago
http://cryptome.org/jya/stb.htm http://cryptome.org/jya/stb.htm
ernestbro 10y ago
Well for one there's being able to control 51% of bitcoin[1] which would let China "prevent transactions of their choosing from gaining any confirmations, thus making them invalid, potentially preventing people from sending Bitcoins between addresses. They could also reverse transactions they send during the time they are in control (allowing double spend transactions), and they could potentially prevent other miners from finding any blocks for a short period of time." [1] https://learncryptography.com/cryptocurrency/51-attack https://learncryptography.com/cryptocurrency/51-attack
- Cthulhu_ 10y ago
  Some other comment I read about this calculated that this supercomputer has about 0.1% or 0.01% of an impact on the total bitcoin calculating power, so effectively negligible. ASICs would work better.
coldtea 10y ago
>Please excuse my ignorance in this area, I was just wondering - why does it matter so much who has the biggest and baddest supercomputer? Shouldn't that which we process on them matter more? Yes, until one starts to lose on most such trivial metrics, and then they have a more substantial problem than losing on trivial metrics... Those things can be long term signs about where the future is going. >A while back I recall reading rumors that China didn't even know what to process on their Tianhe-2. Yeah, those yellow people are so ignorant -- it takes white folks to show them what to process in their supercomputers. Sorry, but those rumours sounds openly racist.
ams6110 10y ago
You'd be surprised that people do buy supercomputers without a real idea (or only a rather vague general idea) of what they're going to do with it. And by people I mean universities. Not unheard of for a university to buy a supercomputer for essentially bragging rights, and then for it to sit underutilized.
- ghshephard 10y ago
  I would think that getting simulation time on a top ranked super computer would be something that you would schedule months, if not years in advance - hard to imagine that having access to a multi-petaflop wouldn't be highly desirable (and useful) for many, many researchers, let alone all the graduate students who spend months of lower-tier computers churning out simulations... I'd be interested to hear from someone who knows/has experience, whether any of the top 100 super computers ever have idle windows.
  - davidmr 10y ago
    I worked on a system that was at one time #3 on the list. There were no substantial idle periods. If the machine was out of maintenance, jobs were being run on it. Depending on the internal structure of the machine, some parts of it might be idle as the scheduler drained other parts to allow space for larger jobs to start, but I wouldn't call it idle. Having done exclusively HPC for almost 16 years now, I can state that there is one and only one immutable law of HPC: grad students will find a way to squeeze out every second of available CPU time on a large system. The amount of effort going into taking advantage of those empty spots in the clusters where smaller jobs can run quickly while the scheduler drains resources for a large job (called backfilling) is tremendous. The thing that sticks with me is what a fantastically complicated problem HPC job scheduling is. I've seen dozens of fresh-faced undergrads or first year grad students come in with a full head of steam and decide that they're going to "solve" HPC job scheduling, but every single one has gotten bogged down in the minutiae and the muck, and I've never seen software that "gets it right". Every scheduler sucks in its own unique way. Whether all of those jobs need an old-fashioned supercomputer is certainly up for debate, but they certainly get used, at least in my experience.
iwontreddit 10y ago
> A while back I recall reading rumors that China didn't even know what to process on their Tianhe-2. That applies to most of supercomputers everywhere. "If you build it, they will come". Besides the knowledge attained in building supercomputers ( which all major nations should know how to do ) and processor technology, the added benefits and new uses of these machines will come later. The internet was created before people really knew what to do with it. The same thing with computers. The same thing with everything else.
Zigurd 10y ago
You would be correct to question if there is a first-order advantage to having the most powerful supercomputer. But it is a national strategic benchmark, like precision manufacturing, certain kinds of biotechnology, rocketry, etc. What matters most might be that China is maturing CPU technology that isn't nearly as congenial for US TLAs to hack in to. It might not matter so much for this supercomputer, but if Chinese suppliers put price ahead of things like opaque management processors, it might lead to tipping the balance away from easily exploitable endpoints.
peter303 10y ago
US is routinely enbarassed by a more accurate European weather forecast computation. Hurricane Sandy prediction was the glaring example. Part of the Euro prowess is due to better physics. But much of it to a finer model they can compute in real time of a larger computer. Everytime you double the resolution, the computing cost increases 16 times in this 4D computation.
- angry_octet 10y ago
  You are implying that the accuracy is mainly due to greater compute. This is simply not true. If the US model could be improved by throwing money for compute at it, that would already have been done. The following paper compares the EU and US ensembles: http://journals.ametsoc.org/doi/full/10.1175/MWR2905.1 http://journals.ametsoc.org/doi/full/10.1175/MWR2905.1

by bjd2385 10y ago

dibanez 10y ago

Its essentially a matter of realistic benchmark acceptance. Right now machines are compared by how well they run this benchmark called LINPACK, which has been criticized for being non-representative of real science codes. As mentioned here [1], China's new system only achieved 0.3% of its peak flops on a slightly more realistic benchmark, HPCG. [1] http://www.hpcwire.com/2016/06/19/china-125-petaflops-sunway/ http://www.hpcwire.com/2016/06/19/china-125-petaflops-sunway...

sanxiyn 10y ago
While Sunway TaihuLight has weak HPCG performance, 0.3% number should be understood in context. Tianhe-2 (#2 system) scores 1.1%, and Titan (#3, US #1 system) scores 1.2% for HPCG. So Sunway TaihuLight is 3~4x worse for HPCG compared to other top systems. Note that K computer (#5 system, Japan) scores 4.9% for HPCG. So Tianhe-2 and Titan are again 4x worse for HPCG compared to systems which score best for HPCG.
- bhouston 10y ago
  Why does the Sunway TaihuLight have bad HPCG performance? I suspect it has to do with memory bandwidth needed to serve 260C on the same chip?
  - sanxiyn 10y ago
    Yes, it's memory and interconnect. I don't think it's as simple as LINPACK bad, HPCG good. LINPACK is representative for some workloads, when compute dominates. HPCG aims to balance compute and memory. There is Graph500, if memory dominates for your workload. By the way, K computer is #1 in Graph500.
    - ams6110 10y ago
      http://www.graph500.org/ http://www.graph500.org/ The interconnect on the Sunway TaihuLight seems to be standard Infiniband, from reading other articles about the system.
aab0 10y ago
I was wondering about third-party benchmarks. As far as I know, the Top500 is pure self-report, and this is a big national-prestige thing...

bluedino 10y ago

>> rumors that China didn't even know what to process on their Tianhe-2. Kind of reminds me of when we heard a rumor than a rival ISP had bought a handful of Sun servers (in the year 2000). We thought they had tends of thousands of customers, figured they would be launching DSL, figured that had thousands of web hosting customers... Turns out they got some weird grant so they spent the cash on those, otherwise they would have lost the money. They went out of business a year later and we kept chugging along with our Pentium III servers.

tluyben2 10y ago
This happened a lot with Sun around that time; I bought 10 E450s for fun from one of the hosters who did exactly that and since then went bankrupt. Great, unbreakable machines.
- ams6110 10y ago
  Bubble dot-com companies rich with VC cash did the same thing. Built massively overprovisioned data centers with expensive Sun servers (because Sun == Internet at that time) and never actually had the traffic to justify even a fraction of it.

bhouston 10y ago

> A while back I recall reading rumors that China didn't even know what to process on their Tianhe-2. That kind of makes a supercomputer look like a pile of hardware, no matter how well it's organized or engraved. There are enough high quality universites in China to make use of it. I can not imagine this is true. There may have not been one big algorithm that it was built for, but university researchers always have stuff to compute.

jonbaer 10y ago

http://cryptome.org/jya/stb.htm http://cryptome.org/jya/stb.htm

ernestbro 10y ago

Well for one there's being able to control 51% of bitcoin[1] which would let China "prevent transactions of their choosing from gaining any confirmations, thus making them invalid, potentially preventing people from sending Bitcoins between addresses. They could also reverse transactions they send during the time they are in control (allowing double spend transactions), and they could potentially prevent other miners from finding any blocks for a short period of time." [1] https://learncryptography.com/cryptocurrency/51-attack https://learncryptography.com/cryptocurrency/51-attack

Cthulhu_ 10y ago
Some other comment I read about this calculated that this supercomputer has about 0.1% or 0.01% of an impact on the total bitcoin calculating power, so effectively negligible. ASICs would work better.

coldtea 10y ago

>Please excuse my ignorance in this area, I was just wondering - why does it matter so much who has the biggest and baddest supercomputer? Shouldn't that which we process on them matter more? Yes, until one starts to lose on most such trivial metrics, and then they have a more substantial problem than losing on trivial metrics... Those things can be long term signs about where the future is going. >A while back I recall reading rumors that China didn't even know what to process on their Tianhe-2. Yeah, those yellow people are so ignorant -- it takes white folks to show them what to process in their supercomputers. Sorry, but those rumours sounds openly racist.

ams6110 10y ago

You'd be surprised that people do buy supercomputers without a real idea (or only a rather vague general idea) of what they're going to do with it. And by people I mean universities. Not unheard of for a university to buy a supercomputer for essentially bragging rights, and then for it to sit underutilized.

ghshephard 10y ago
I would think that getting simulation time on a top ranked super computer would be something that you would schedule months, if not years in advance - hard to imagine that having access to a multi-petaflop wouldn't be highly desirable (and useful) for many, many researchers, let alone all the graduate students who spend months of lower-tier computers churning out simulations... I'd be interested to hear from someone who knows/has experience, whether any of the top 100 super computers ever have idle windows.
- davidmr 10y ago
  I worked on a system that was at one time #3 on the list. There were no substantial idle periods. If the machine was out of maintenance, jobs were being run on it. Depending on the internal structure of the machine, some parts of it might be idle as the scheduler drained other parts to allow space for larger jobs to start, but I wouldn't call it idle. Having done exclusively HPC for almost 16 years now, I can state that there is one and only one immutable law of HPC: grad students will find a way to squeeze out every second of available CPU time on a large system. The amount of effort going into taking advantage of those empty spots in the clusters where smaller jobs can run quickly while the scheduler drains resources for a large job (called backfilling) is tremendous. The thing that sticks with me is what a fantastically complicated problem HPC job scheduling is. I've seen dozens of fresh-faced undergrads or first year grad students come in with a full head of steam and decide that they're going to "solve" HPC job scheduling, but every single one has gotten bogged down in the minutiae and the muck, and I've never seen software that "gets it right". Every scheduler sucks in its own unique way. Whether all of those jobs need an old-fashioned supercomputer is certainly up for debate, but they certainly get used, at least in my experience.

iwontreddit 10y ago

> A while back I recall reading rumors that China didn't even know what to process on their Tianhe-2. That applies to most of supercomputers everywhere. "If you build it, they will come". Besides the knowledge attained in building supercomputers ( which all major nations should know how to do ) and processor technology, the added benefits and new uses of these machines will come later. The internet was created before people really knew what to do with it. The same thing with computers. The same thing with everything else.

Zigurd 10y ago

You would be correct to question if there is a first-order advantage to having the most powerful supercomputer. But it is a national strategic benchmark, like precision manufacturing, certain kinds of biotechnology, rocketry, etc. What matters most might be that China is maturing CPU technology that isn't nearly as congenial for US TLAs to hack in to. It might not matter so much for this supercomputer, but if Chinese suppliers put price ahead of things like opaque management processors, it might lead to tipping the balance away from easily exploitable endpoints.

peter303 10y ago

US is routinely enbarassed by a more accurate European weather forecast computation. Hurricane Sandy prediction was the glaring example. Part of the Euro prowess is due to better physics. But much of it to a finer model they can compute in real time of a larger computer. Everytime you double the resolution, the computing cost increases 16 times in this 4D computation.

angry_octet 10y ago
You are implying that the accuracy is mainly due to greater compute. This is simply not true. If the US model could be improved by throwing money for compute at it, that would already have been done. The following paper compares the EU and US ensembles: http://journals.ametsoc.org/doi/full/10.1175/MWR2905.1 http://journals.ametsoc.org/doi/full/10.1175/MWR2905.1