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> Nvidia B200s ... offer 2-3x the performance of H100s For ML, not for HPC. ML and HPC are two completely different, only loosely related fields. ML tasks are
by maratc 2y ago
> Nvidia B200s ... offer 2-3x the performance of H100s
For ML, not for HPC. ML and HPC are two completely different, only loosely related fields.
ML tasks are doing great with low precision, 16 and 8 bit precision is fine, arguably good results can be achieved even with 4 bit precision [0][1]. That won't do for HPC tasks, like predicting global weather, computational biology, etc. -- one would need 64 to 128 bit precision for that.
Nvidia needs to decide how to divide the billions of transistors on their new silicon. Greatly oversimplifying, they can choose to make one of the following:
* Card A with *n* FP64 cores, or
* Card B with *2n* FP32 cores, or
* Card C with *4n* FP16 cores, or
* Card D with *8n* FP8 cores, or (theoretically)
* Card E with *16n* FP4 cores (not sure if FP4 is a thing).
Card A would give HPC guys n usable cores, and it would give ML guys n usable cores. On the other end, Card E would give ML guys 16n usable cores (and zero usable cores for HPC guys). It's no wonder that HPC crowd wants Nvidia to produce Card A, while ML crowd wants Nvidia to produce Card E. Given that all the hype and the money are currently with the ML guys (and $NVDA reflects that), Nvidia will make a combination of different cores that is much much closer to Card E than it is to Card A.
Their new offerings are arguably worse than their older offerings for HPC tasks, and the feeling with the HPC crowd is that "Nvidia and AMD are in the process of abandoning this market".
[0] https://papers.nips.cc/paper/2020/file/13b919438259814cd5be8cb45877d577-Paper.pdf https://papers.nips.cc/paper/2020/file/13b919438259814cd5be8...
[1] https://arxiv.org/abs/2212.09720 https://arxiv.org/abs/2212.09720
- touisteur 2y agoWith the B100 somehow announced to have lower scalar FP64 throughput than the H100 (did they remove the DP tensor cores ?), one will have to rely on Ozaki schemes (dgemm with int8 tensor cores) and lots of the recent body of work on mixed-precision linear algebra show there's a lot of computing power to be harnessed from Tensor Cores. One of the problems of HPC now is a level of ossification of some codebases (or the lack of availability of porting/coding/optimizing people). You shouldn't have to rewrite everything every 5 years but the hardware constructors go where they go and we still haven't found the right level of abstraction to avoid big porting efforts.
- ipsum2 2y agoYes, that's a great point that I missed. From anecdotal evidence, it seems more people are using supercomputers for ML use cases, that would have been traditionally done by HPC. (eg training models for weather forecasts)
- layla5alive 2y agoYou've heard of SIMD - it's possible to do both, in terms of throughput, with instruction/scheduler/port complexity overhead of course.
- dragontamer 2y agoDoesn't multiply area scale at O(n^2 * log(n)) ?? (At least, I'm pretty sure the Wallace Tree Multiplier circuit is somewhere in that order). So a 64-bit multiplier is something like 32x more area than a 16-bit multiplier. But what you say is correct for RAM area or the number of bits you need for register space. So taken holistically, it's difficult to say... Okay, 64-bit FP is only like 53-bits and 16-bit FP is actually like 11 bits. But you know what I mean. I'm still doing quick napkin math here, nothing formal. ------- We can ignore adders and subtractor circuits because they are so small. Division is often implemented as reciprocal followed by multiplication circuits for floating point (true division is very expensive).
- deleted 2y ago[deleted]