First true exascale supercomputer? • Hacker News Board

Re: First true exascale supercomputer?

#21

Post by latchkey » Wed, Jul 06, 2022, 4:58 PM UTC

eslaught wrote: post #19

jakear wrote: post #6

The spec sheet mentions they're moving from CUDA powering their prior supercomputer to "HIP" for this one. This is the first I've heard of HIP, does anyone have experience with it? My impression was that GPU programming tended to mean CUDA, which isn't cross platform (as opposed to HIP). https://developer.amd.com/resources/rocm-learning-center/fun... .

HIP is basically CUDA with s/cuda/hip/g. My experience is that the stack is pretty rough around the edges. But when it works, you (almost) literally find-and-replace, and it pretty much works as advertised. However, just because you can get to a correct code doesn't necessarily mean that code will achieve optimal performance (without further tuning, of course).

Not only tuning the code, but also the bazillion knobs on the GPUs themselves.

Re: First true exascale supercomputer?

#22

Post by freemint » Wed, Jul 06, 2022, 5:02 PM UTC

causi wrote: post #2

It feels like it's been a long time since supercomputers were interesting. They're just oodles of identical processors connected together like legos. "We can afford more bricks than the next guy" is not exciting. When was the last time we had a "fastest supercomputer" that could do something the second-fastest couldn't also do?

Well fundamentally all super computers are turing machines. So one can do X while Y can not doesn't really make sense in that context.

However the second-fastest (ARM based Fugaku) absolutely wipes the floor with the fastest in certain tasks due to a difference in interconnect topology. Fugaku futhermore has no GPUs unlike many other super computers and instead a CPU with some vector instructions, leading to a different programming model.

If you are more into specialized hardware, Anton3 is amazing.

Re: First true exascale supercomputer?

#23

Post by pclmulqdq » Wed, Jul 06, 2022, 5:03 PM UTC

dixie_land wrote: post #12

seiferteric wrote: post #3

> and relies on gigabit ethernet for data transfer. This seems suprising to me, I would have expected 10Gb at least, if not something like inifiniband.

seems to be a proprietary interconnect that is “Ethernet compatible” https://www.hpe.com/us/en/compute/hpc/slingshot-interconnect...

As far as I know, Slingshot uses a layer 1 that is exactly the same as Ethernet and allows layer 2 ethernet packets to enter switches. However, it has several layer 1/2 extensions that let it look more like Infiniband to use cases that need it, including flow control and congestion control.

Re: First true exascale supercomputer?

#24

Post by greggsy » Wed, Jul 06, 2022, 5:05 PM UTC

oefrha wrote: post #18

inasio wrote: post #16

There's a bit of drama in that there are unofficial reports of two systems in China with higher performance [0], the arXiv paper listed below talks about a 40 million core system with around double theoretical performance than Frontier, and there's apparently a second system online with similar performance. I personally suspect that they didn't submit benchmarks to the top500 simply because those don't run well enoug…

I heard they won’t submit anymore so as to not draw further scrutiny and possible sanctions onto their suppliers. Not sure if true, but keeping a low profile certainly makes sense given the blows dealt to the more visible vendors in the past few years.

What are the concerns for vendors?

Re: First true exascale supercomputer?

#25

Post by convolvatron » Wed, Jul 06, 2022, 5:05 PM UTC

zamadatix wrote: post #13

causi wrote: post #2

It feels like it's been a long time since supercomputers were interesting. They're just oodles of identical processors connected together like legos. "We can afford more bricks than the next guy" is not exciting. When was the last time we had a "fastest supercomputer" that could do something the second-fastest couldn't also do?

Speed is just the measure of how fast it does something not a measure of what it's capable of doing. I wouldn't expect to divine more information like "what new things can it do" from that number alone outside "things we didn't have enough compute time for before we do now". Lego style supercomputers are still very interesting in my eye though. As the technical complexity involved in scaling the raw compute performan…

there is also a huge amount of work remaining to be done in programming models and consistency.

Re: First true exascale supercomputer?

#26

Post by krylon » Wed, Jul 06, 2022, 5:10 PM UTC

sriram_malhar wrote: post #15

21 MW power! Insane. Interestingly, the second one is 30 MW.

For reference, Roadrunner, which was the first petascale system in 2008, used 2.35 MW (according to Wikipedia). So this one gives us 1,000 times the performance for 10 times the energy. From a performance/Watt perspective, this is an impressive improvement.

EDIT: Wikipedia also says Roadrunner was not considered power-efficient in its day, which led to it being decommissioned after only five years of operation.

Re: First true exascale supercomputer?

#27

Post by rfoo » Wed, Jul 06, 2022, 5:19 PM UTC

causi wrote: post #2

It feels like it's been a long time since supercomputers were interesting. They're just oodles of identical processors connected together like legos. "We can afford more bricks than the next guy" is not exciting. When was the last time we had a "fastest supercomputer" that could do something the second-fastest couldn't also do?

> They're just oodles of identical processors connected together like legos.

That's the Cloud, not supercomputing. Supercomputing is all about interconnect.

Re: First true exascale supercomputer?

#28

Post by perihelions » Wed, Jul 06, 2022, 5:26 PM UTC

greggsy wrote: post #24

oefrha wrote: post #18

Earlier quoted context omitted.

I heard they won’t submit anymore so as to not draw further scrutiny and possible sanctions onto their suppliers. Not sure if true, but keeping a low profile certainly makes sense given the blows dealt to the more visible vendors in the past few years.

What are the concerns for vendors?

US banned the sale of American HPC components to Chinese supercomputers.

https://news.ycombinator.com/item?id=9349116 (2015, 93 comments)

https://news.ycombinator.com/item?id=26740371 (2021, 151 comments) etc.

Re: First true exascale supercomputer?

#29

Post by agumonkey » Wed, Jul 06, 2022, 5:32 PM UTC

rfoo wrote: post #27

causi wrote: post #2

It feels like it's been a long time since supercomputers were interesting. They're just oodles of identical processors connected together like legos. "We can afford more bricks than the next guy" is not exciting. When was the last time we had a "fastest supercomputer" that could do something the second-fastest couldn't also do?

> They're just oodles of identical processors connected together like legos. That's the Cloud, not supercomputing. Supercomputing is all about interconnect.

I also wonder how the software side of things changes in those settings, how do people design program / algorithms around fast and wide data path like these.

Re: First true exascale supercomputer?

#30

Post by linksnapzz » Wed, Jul 06, 2022, 5:32 PM UTC

CoastalCoder wrote: post #7

I used to be really excited about supercomputers. It's part of why I pursued HPC-related work. But I think that having no interest in their actual applications has curbed my enthusiasm. I wish I could make a good living in something that interested more.

I love the applications, but I'm dismayed at the stagnation in programming models used to get the best performance out of modern clusters. This sums up my feelings:

https://www.usenix.org/conference/atc21/presentation/fri-key...