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borramakot | 4 years ago | on: Switching from GMP to GCC's __int128 reduced run time by 95% (2016)

Given the author mentions multiple cores being available, I'd guess you could use any method, including MPI, to distribute the computation. But whether you used 1 core or 10k cores, it would be nice to have a 20x speedup on each core via this arithmetic/fixed size optimization. Since that's the focus of the article, communication technologies feel pretty unrelated.

borramakot | 4 years ago | on: Are there flaws in some ARM64 instructions?

The amount of effort and extra hardware required to maintain this reproducibility across different hardware (cpu generations, GPU hardware/drivers, etc) feels insane to me. For example, people seem extremely interested in performance, but insist on using the much slower modes in MKL to maintain the bottom few bits of their golden data.

Do you find this genuinely important? If not, have you had any success encouraging e.g. validating against golden data in a non-bitwise comparison?

borramakot | 4 years ago | on: Compressing JSON: Gzip vs. Zstd

If I recall, the zstd binary has a mode that is basically "adapt the compression ratio so that compression isn't the bottleneck", but I didn't have a chance to try it. Have you used that?

borramakot | 5 years ago | on: Put not thy trust in Nate Silver

(I have fairly minor quibbles with some of Nate's modeling ideas, but I broadly mean to be defending him).

I don't mean to imply 2016 was a black swan event- I agree that ~30% was probably as accurate a take as could be achieved (most evidence that seems reasonable to use indicated a lead for Clinton, but that it wouldn't be that surprising for that lead to be overcome). I just mean that the model assumes a fairly normal election environment, without like a huge attack on Election day or something on election day.

The N=3 comment was meant specifically for evaluating their calibration, not the data they use for their model.

borramakot | 5 years ago | on: Put not thy trust in Nate Silver

I don't think this article provides strong evidence that they are well calibrated on the presidential election specifically (sample size N=3), or that they are correctly accounting for rare black swan events, but it does seem to imply that the criticisms about "538 claims victory no matter what because they always have non-zero probabilities" are oversimplified.

borramakot | 5 years ago | on: Zstandard

LZ4 seems really nice for data with a lot of repetition, but not having any symbolic entropy encoder can really kill the compression for some data. I often default to LZ4, and used to fall back to gzip if that doesn't work well, but I've been really impressed with zstd. It's not as commonly used, but if I'm not concerned about interoperability, I'll be trying to use a lot more zstd.

borramakot | 5 years ago | on: Next-Generation IBM POWER10 Processor

So, the main result of designing a CPU is a series of masks that essentially indicate where to put what. For example, in this layer, inject boron anywhere the mask doesn't block. The masks aren't wafer sized- they are pretty small, and a machine moves the mask from position to position across the wafer to re-use it. But, at least when I was working on this, some masks would be larger than an individual square (die)- maybe the mask could do 2x2 at a time. In that case, maybe the application of the mask would get you one complete die, and three die off the edge.

borramakot | 5 years ago | on: The History, Status, and Future of FPGAs

I may not have said it well, but I broadly agree with you. If a workload needs high performance but not consistently (e.g. because you're doing serial tests by swapping bitstreams), predictably (e.g. because you need flexibility for network stuff you can't predict at design time), or with enough volume (e.g. costs in the low millions are prohibitive), an ASIC isn't the right solution.

But my point is that for FPGAs to come to prominence as a major computation paradigm, it probably won't be because it outperforms GPU on one really big workload like bitcoin or genetic analysis or something. It'll have to be a moderately large number of medium scale workloads.

borramakot | 5 years ago | on: The History, Status, and Future of FPGAs

Just to throw in one more complication, I'll assert that the only benefits of FPGAs over ASICs are one time costs and time to market. Those are big benefits, but almost by definition, they aren't as important for workloads that are large scale and stable. So, if you do have a workload that's an excellent match for FPGAs, and if that workload will have lots of long term volume, you should make an ASIC for it.

So, for FPGAs to be the next big thing in HPC, you'd need to find a class of workloads that benefit from the FPGA architecture, for long enough and with high enough volume to be worth the work to move over, and are also unstable or low volume enough that it's not worth making them their own chip.

borramakot | 5 years ago | on: Tech sector job interviews assess anxiety, not software skills: study

I agree that's a really striking and suggestive result, but keep in mind the sub-sample size there is four passing on the private side and six failing on the public side. My guess is there's a real and meaningful effect there, but it may not be to the degree that sentence without context would suggest.
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