Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

The art of high performance computing

theartofhpc.com

Post reply on HN
Print view View original

71–80 of 125 posts

Re: The art of high performance computing

#71

Post by eutropia »

gopher_space wrote: post #67
bayindirh wrote: post #62

Earlier quoted context omitted.

Because it’s complex. Even more complex than “engineered” air. You need two circuits, and a CDU between them. Coolants needs maintaining. You add antifreeze, biocides, etc. Air is brute force. It cools everything it touches. Liquid cooling is serialized in a node. Two sockets? Second will be hotter. HBA not making good contact? It’ll overheat. You add extensive leak detection subsystems, the amount of coolant moving…

What's this all look like without an atmosphere?

Worse, heat dissipation is a major constraint for spacecraft and satellites because you can only radiate heat away as infrared photons.

Re: The art of high performance computing

#72

Post by cyrillite »

LASR wrote: post #48

The hardware / datacenter side of this is equally fascinating. I used to work in AWS, but on the software / services side of things. But now and then, we would crash some talks from the datacenter folks. One key relevation for me was that increasing compute power in DCs is primarily a thermodynamics problem than actual computing. The nodes have become so dense that shipping power in and shipping heat out, with all ki…

Is there any good data on the scale of this problem or that can be used to visualise it?

What is the cutting edge of cooling tech like?

Re: The art of high performance computing

#73

Post by trentnelson »

convolvatron wrote: post #31
crabbone wrote: post #20

Earlier quoted context omitted.

You'd be surprised how actually backwards and primitive are the tools used in HPC. Take for instance the so-called workload managers, of which the most popular ones are Slurm, PBS, UGE, LSF. Only Slurm is really open-source, PBS has a community edition, the rest is proprietary stuff executed in the best traditions of enterprise software which locks you into using pathetically bad tools, ancient and backwards tech wit…

HPC software is one area where we have arguably regressed in the last 30 years. Chapel is the only light I see in the darkness

Want to elaborate more on Chapel? I’ve recently being tasked with integrating Chapel into our system and it’s quite interesting.

Re: The art of high performance computing

#74

Post by [deleted] »

adev_ wrote: post #60
cogman10 wrote: post #56

Earlier quoted context omitted.

It always made me wonder why liquid cooling wasn't more of a thing for datacenters. Water has a massive amount of thermal capacity and can quickly and in bulk be cooled to optimal temperatures. You'd probably still need fans and AC to dissipate heat of non-liquid cooled parts, but for the big energy items like CPUs and GPUs/compute engines, you could ship out huge amounts of heat fairly quickly and directly. I guess…

> It always made me wonder why liquid cooling wasn't more of a thing for datacenters. Liquid cooling is almost a defacto-standard in data centers in the HPC world. The Top of the TOP500 machines are all liquid cooled. Not by choice, but due to physics constraints. There is a big gap in power density between the HPC world and the usual datacenter-commodity-hardware world. Commodity DS are designed with the assumption…

[deleted]

Re: The art of high performance computing

#75

Post by danparsonson »

s_Hogg wrote: post #66
throwawaaarrgh wrote: post #43

Earlier quoted context omitted.

I always found that funny too. A business who needs a powerful computing solution can come up with some amazingly robust stuff, whereas science/research just buys a big mainframe and hopes it works.

I was working in a company that had been spun out of a university until recently and it was shocking how hopeless the researchers were. I've always been critical of how poor the job security in academia is but you'd think it's still too much given how slapdash some of the crap you see is. We basically had to reinvent their product from the ground up, awful.

This is probably a naive question but isn't that the point of having developers on staff? The researchers aren't coders and vice versa, so having researchers produce prototypes that are productized by engineers makes sense to me.

Re: The art of high performance computing

#76

Post by huitzitziltzin »

toddm wrote: post #34

Kudos to Victor for assembling such a wonderful resource! While I am not acquainted with him personally, I did my doctoral work at UT Austin the the 1990's and had the privilege of working with the resources (Cray Y-MP, IBM SP/2 Winterhawk, and mostly on Lonestar, a host name which pointed to a Cray T3E at the time) maintained by TACC (one of my Ph.D. committee members is still on staff!) to complete my work (TACC wa…

Dealt with him via TACC for a big simulation I did and was grateful enough for his help to buy a paper copy of the first volume in the series. Very interesting though a bit outside of my area. I will look at the others and encourage anyone interested to check them out.

Re: The art of high performance computing

#77

Post by taneq »

eutropia wrote: post #71
gopher_space wrote: post #67

Earlier quoted context omitted.

What's this all look like without an atmosphere?

Worse, heat dissipation is a major constraint for spacecraft and satellites because you can only radiate heat away as infrared photons.

Doesn’t have to be infrared but yeah, space isn’t “cold” so much as it’s an insulator.

Re: The art of high performance computing

#78

Post by rramadass »

jebarker wrote: post #69
leopoldj wrote: post #64

Earlier quoted context omitted.

C++ programmer and educator here. This (volume 3) is well organized good beginner level teaching material. You probably know most of it already. I was looking for range-based for loop, std::array and std::span and happy to see that they are all there. Because this book relates to HPC, I'd add a few things: Return Value Optimization, move semantics, and in the recursive function section a note about Tail Call Optimiza…

That's great - thank-you. Assuming I work through this quickly, what resources would you recommend as a follow-on?

I am not the person you asked the question to, but my recommendation would be;

1) Discovering Modern C++: An Intensive Course for Scientists, Engineers, and Programmers by Peter Gottschling - Not too thick and focuses on how to program in the language.

2) Software Architecture with C++: Design modern systems using effective architecture concepts, design patterns, and techniques with C++20 by Adrian Ostrowski et al. - Shows how to use C++ in the modern way/ecosystems i.e. with CI/CD, Microservices etc.

Optional but highly recommended;

a) Scientific and Engineering C++: An Introduction with Advanced Techniques and Examples by Barton & Nackman - Old pre-Modern C++ book which pioneered many of the techniques which have now become common. One of the best for learning C++ design.

Re: The art of high performance computing

#79

Post by m-ee »

s_Hogg wrote: post #66
throwawaaarrgh wrote: post #43

Earlier quoted context omitted.

I always found that funny too. A business who needs a powerful computing solution can come up with some amazingly robust stuff, whereas science/research just buys a big mainframe and hopes it works.

I was working in a company that had been spun out of a university until recently and it was shocking how hopeless the researchers were. I've always been critical of how poor the job security in academia is but you'd think it's still too much given how slapdash some of the crap you see is. We basically had to reinvent their product from the ground up, awful.

I've had very similar experiences working with former researchers including at a university spinout. Mechanical rather than CS. It was perplexing how they still carried the elitism that industry was mostly for people who can't hack it in academia given the quality of their work. Would be unacceptable coming from a new hire PD engineer at Apple yet you're demanding respect because you used to lead a whole lab apparently producing rubbish?

Re: The art of high performance computing

#80

Post by rramadass »

danparsonson wrote: post #75
s_Hogg wrote: post #66

Earlier quoted context omitted.

I was working in a company that had been spun out of a university until recently and it was shocking how hopeless the researchers were. I've always been critical of how poor the job security in academia is but you'd think it's still too much given how slapdash some of the crap you see is. We basically had to reinvent their product from the ground up, awful.

This is probably a naive question but isn't that the point of having developers on staff? The researchers aren't coders and vice versa, so having researchers produce prototypes that are productized by engineers makes sense to me.

Exactly! This is how it should be.

Researchers/Scientists with their hard earned PhDs should only concentrate on doing cutting-edge "researchy" stuff. It is hard enough that they should not be asked to learn all the intricacies/problems inherent in Software Development. That is the domain of a "Professional Software Engineer".

There is now in fact a new class called "Research Software Engineer" who are Software Developers working in Research developing code specific to their needs - https://www.nature.com/articles/d41586-022-01516-2 and https://en.wikipedia.org/wiki/Research_software_engineering

Post reply on HN