11

I haven't worked in quantum chemistry specifically, but I've worked in other areas where high performance is a correctness requirement (along with scientific accuracy), so I think we're on the same page here. Broad but shallow knowledge of all of the above is absolutely necessary for the team as a whole. Deep knowledge can be acquired as needed, or hired as ...


6

The term "vector pipeline" was used in the 1970's to describe vector processing at a time when a single vector instruction might (for example) compute the sum of two vectors of floating point numbers using a single pipelined floating point arithmetic unit. Pairs of floating point numbers would be brought from memory into the pipelined arithmetic unit to be ...


5

Most modern systems are Princeton in the sense that the same memory system is used for data and instructions, although memory management systems often keep instructions and data in separate pages and user code may not be able to write into memory that contains executable instructions for security reasons. At a different level, there are typically separate ...


3

Instruction Level Parallelism (ILP) is complementary to vectorization, but both require sufficient cache and register space. Our paper (it's fun to learn that your own paper answers your question, eh?) analyzes this in detail for stencil operations on Blue Gene/P, combining vectorization and unroll/jam to expose sufficient parallelism while using registers ...


3

I'm barely old enough to understand this, but my understanding is that vector pipelining in the old days allowed for one vector instruction in the pipeline to use the result from the vector instruction ahead of it. I believe that now on the most common vector architectures this is not possible. Vector instructions are pipelined, but only insofar as they are ...


3

I want to support the response from @Pseudonym, who makes the point that not everyone in the team needs to contribute to every aspect of the project. Something related to consider is that you are presently at the beginning of your career, and will be making whatever contribution you are capable of. But perhaps you will still be working in the same general ...


2

Ideally in your education you learn various subjects out of curiosity and in order to discover, if you're lucky, those you really like. And then you study those primarily because you like them. One or two of them may continue to intrigue and stimulate, and you end up knowing them inadvertently to a very great detail. Studying what you think is needed for ...


2

Resilience will be the limiting factor to exascale. It is going to be relatively straightforward to build an exascale system for less than $1B that uses less than 50MW if the machine is allowed to crash every 15 minutes or compute the wrong answer most of the time. Silent memory errors are already occurring and engineering system software and algorithms to ...


2

Yes, obsolete. Algorithmic analysis by flops, or any other method, is only as useful as the abstract model of the machine when considering the size of the problem at hand. Actual performance depends both on the implementation and the hardware, and the applicability of any abstract model for the latter to reality is decreasing over time. For example, as you ...


1

First, you can model turbulence using averages; e.g.: RANS. As you will see, higher order moments appear and you need to find a way to close your equations. Now that's about mean flows since you want to find solution for the mean values of your variables. Second, you can derive a stochastic form of the Navier Stokes Equation and solve the probability ...


1

This obscure 1990 technical review from the U of Sydney refers to "vector pipelining" as a means of implementing SIMD under the hood — if you suppose that the processor doesn't have enough logic to execute a vector instruction in "full width" at one go, but that the instruction can be broken down into sub-operations (at a level below instruction set level), ...


1

There's a lot of information online that search engines are capable of finding. Here's three hits to get the ball rolling: http://dx.doi.org/10.1109/TC.2010.121 http://smartech.gatech.edu/bitstream/handle/1853/45737/GT-CSE-2012-01.pdf http://dl.acm.org/citation.cfm?doid=2425676.2425691


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