NSA director be making that smug frog face right about now
Supercomputers: Obama orders world's fastest computer
131–140 of 179 posts
Re: Supercomputers: Obama orders world's fastest computer
#132Earlier quoted context omitted.
CG isn't truly asynchronous due to its reductions. It can be pipelined in various ways (we have several implementations in PETSc), but performance requires a quality implementation of asynchronous reduction (e.g., MPI_Iallreduce) which the vendors have been slow about developing (I've been working with some on fixing this and Cray has made recent progress). With respect to deep learning and other applications using C…
You might want to read up on Sibyl.
The information I've seen about Sibyl (the Google ML system, not the genomics package (http://sybil.sourceforge.net/documentation.html)) says it is basically doing logistic regression using a parallel algorithm (Collins, Schapire, Singer) with a transpose on each iteration. Without knowing more about the problem sizes and data sparsity/irregularity, I expect the transpose to be a significant expense. I'd be happy to read more if you have access to further technical information, but it's not clear how this comment relates to your previous question about CG and deep learning. As it relates to HPGMG, I think my previous response covers the important performance dimensions. I'd be happy to discuss further over email.
Re: Supercomputers: Obama orders world's fastest computer
#133Earlier quoted context omitted.
> especially when the community has little or no skill at building NG Internet HPC systems I would argue that the community of people who actually have the skills to take advantage of the interconnects in a classic HPC system is vanishingly small, and in consequence we've overbuilt them on an epic scale. Allow me to vent. I had the good fortune to have a login on a "petascale" HPC system, and access to an allocation…
Ah, a Cray. Buck up; there are better supercomputers.
It was, in fact. How did you infer that?
Re: Supercomputers: Obama orders world's fastest computer
#134Earlier quoted context omitted.
I use i7 2600k at 5.0 GHz for some time. Probably best option for ordinary human.
Interesting! I'm running this one: Intel® Core™ i7-4790K at 4.x Ghz (currently 4.2 for long term big problem stability) What does your setup look like? Cooling, RAM, etc...? And is it good for long term, like say crunch on it for a week type problems?
Water cooling from Antec, it fits into regular desktop case. Under load it makes sound like hoover. Some cheap RAM, some motherboard for $200, 500 Watt PSU.
I use it for IDE (Scala compiler is slow).
No problem with stability, it ran a few times over weekend at full load. Maximal temperature about 90C. I have put quite high voltage. Over summer it goes down to 4.8GHz.
Re: Supercomputers: Obama orders world's fastest computer
#135Re: Supercomputers: Obama orders world's fastest computer
#136Re: Supercomputers: Obama orders world's fastest computer
#137I suppose that "supercomputers" are all multi-processor these days, so the colossal FLOP numbers are counted as an aggregation over many processors and one has to coordinate these processors in any application that takes advantage of the FLOP specs. Now I am curious what is the fastest single processor?
Looks like somebody got to ~8.7GHz through overclocking a ~4GHz cpu.
http://hwbot.org/submission/%202615355
I happened to catch an overclocking competition being streamed on Twitch one late night many months ago. It was really interesting to see more about the methods and techniques involved and how the competitions work.
Re: Supercomputers: Obama orders world's fastest computer
#138It looks like they are explicitly saying they want to make a machine that works for both types of HPC -- classic low-latency high-bandwidth internode communication (physics simulations) and modern Internet-driver high-bandwidth storage/node communications. This is because the supercomputer community has long ignored the Internet-style of computation (MapReduce etc). But most of the new generation of scientists are ad…
> especially when the community has little or no skill at building NG Internet HPC systems I would argue that the community of people who actually have the skills to take advantage of the interconnects in a classic HPC system is vanishingly small, and in consequence we've overbuilt them on an epic scale. Allow me to vent. I had the good fortune to have a login on a "petascale" HPC system, and access to an allocation…
The problem you were seeing wasn't the supercomputer per se, it was the sheer awfulness of Lustre.
Re: Supercomputers: Obama orders world's fastest computer
#139Earlier quoted context omitted.
That's true for many purposes, but is it true for physical simulations? Don't they need communication on every time step?
I would say no. Here is my argument: when I worked for DOE, everybody told me I had to run my MD simulations on a super computer using all the processors, and I would judged on my parallel efficiency. This meant using a code that used MPI to communicate at every (or every N) timesteps. I asked, instead, "Why not just run N independent simulations, and pool the results?" In this case, you run an M-thread simulation on…
I know some people in the life sciences who were strongly encouraged to get Titan time. When they applied and presented ORNL with their embarrassingly parallel code, they were told to go away.
Re: Supercomputers: Obama orders world's fastest computer
#140It looks like they are explicitly saying they want to make a machine that works for both types of HPC -- classic low-latency high-bandwidth internode communication (physics simulations) and modern Internet-driver high-bandwidth storage/node communications. This is because the supercomputer community has long ignored the Internet-style of computation (MapReduce etc). But most of the new generation of scientists are ad…
It is important to not conflate "massively parallel" (HPC) and "massively distributed" (Internet-scale), they have different architectural requirements and solve different classes of problem. People with competency in either of these areas tend to overestimate their understanding of the other but they are not solving the same computer science problems even though they look similar on the surface. Massively distribute…
Agreed. I wrote my thoughts on it going distributed here: