Faster Population Counts Using AVX2 Instructions · HackerPapers discussions

Faster Population Counts Using AVX2 Instructions — mentioned by Lammy

Mon, 12 Sep 2022 21:35:27 GMT

Best throw away all your CPUs then too: https://groups.google.com/g/comp.arch/c/UXEi7G6WHuU/m/Z2z7fC... https://vaibhavsagar.com/blog/2019/09/08/popcount/ https://arxiv.org/abs/1611.07612

Paper and discussion history. A mention is not an endorsement.

Faster Population Counts Using AVX2 Instructions — HN submission

Wed, 28 Jul 2021 16:40:46 GMT

Faster Population Counts Using AVX2 Instructions [pdf]

3 points; 0 discussion replies on HN. Paper and source history. A submission is not an endorsement.

Faster Population Counts Using AVX2 Instructions — mentioned by dlemire

Fri, 11 Jun 2021 18:27:10 GMT

You can also go faster using SIMD instructions if you need to compute wider population counts (beyond 64 bits): Faster Population Counts Using AVX2 Instructions, Computer Journal, Volume 61, Issue 1, 2018 https://arxiv.org/abs/1611.07612

Paper and discussion history. A mention is not an endorsement.

Faster Population Counts Using AVX2 Instructions — mentioned by eesmith

Mon, 09 Sep 2019 03:13:22 GMT

Though, interestingly, if AVX2 is available then Lemire's CRoaring package uses a Harley-Seal popcount implementation, at https://github.com/RoaringBitmap/CRoaring/blob/master/includ... , rather than the POPCNT64 instruction. Because it's faster - https://arxiv.org/abs/1611.07612 .

Paper and discussion history. A mention is not an endorsement.

Faster Population Counts Using AVX2 Instructions — mentioned by nkurz

Tue, 18 Jun 2019 01:55:44 GMT

You are obviously already on top of the concept, but in the paper "Faster Population Counts Using AVX2 Instructions" we tried to give a clear explanation (with diagrams) of how it can be faster to roll your own popcnt using Carry-Save-Adders: https://arxiv.org/abs/1611.07612

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Faster Population Counts Using AVX2 Instructions — mentioned by indescions_2018

Fri, 11 May 2018 14:11:44 GMT

See also: The Aggregate Magic Algorithms page http://aggregate.org/MAGIC/ For example, Population Count instructions exist. But may actually be microcoded to count one bit per cycle. Vectorizing your tallies can yield log time speedups: Faster Population Counts Using AVX2 Instructions https://arxiv.org/pdf/1611.07612.pdf

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Faster Population Counts Using AVX2 Instructions — mentioned by nkurz

Wed, 07 Dec 2016 02:03:30 GMT

I work with the author regularly, and am inclined to a more charitable reading. I was serious when I suggested that he'd love to receive your Rust benchmark showing that it has no slowdown, and would happily include a note about them. I'm not sure of the the purpose of the "obfuscation" comments. I'd guess that they were intended as jokes, but missed the target. Rather than mocking the use of reduce, I think his goal was probably to defend the utility of the humble for loop. On a larger level, both he and I have a concern that people often assume "a sufficiently clever compiler" without…

Paper and discussion history. A mention is not an endorsement.

Faster Population Counts Using AVX2 Instructions — HN submission

Thu, 24 Nov 2016 21:13:45 GMT

Faster Population Counts Using AVX2 Instructions

15 points; 0 discussion replies on HN. Paper and source history. A submission is not an endorsement.