simdutf VS nativejson-benchmark

The project was mostly inspired by simdutf [0] which has been around for a couple of years already, and I don't think iconv has any of its vectorized implementations for other architectures.

[0] https://github.com/simdutf/simdutf

I'm actually doing something quite similar in my, in progress, unicode conversion routines.

For utf8 validation there is a clever algorithm that uses three 4-bit look-ups to detect utf8 errors: https://github.com/simdutf/simdutf/blob/master/src/icelake/i...

Aside on LMUL, if you haven't encountered it yet: rvv allows you to group vector registers when configuring the vector configuration with vsetvl such that vector instruction operate on multiple vector registers at once. That is, with LMUL=1 you have v0,v1...v31. With LMUL=2 you effectively have v0,v2,...v30, where each vector register is twice as large. with LMUL=4 v0,v4,...v28, with LMUL=8 v0,v8,...v24.

In my code, I happen to read the data with LMUL=2. The trivial implementation would just call vrgather.vv with LMUL=2, but since we only need a lookup table with 128 bits, LMUL=1 would be enough to store the lookup table (V requires a minimum VLEN of 128 bits).

So instead I do six LMUL=1 vrgather.vv's instead of three LMUL=2 vrgather.vv's because there is no lane crossing required and this will run faster in hardware: (see [0] for a relevant mico benchmark)

        # codegen for equivalent of that function

utf8 normalization, stemming, case insensitive comparison. https://github.com/unicode-rs example for rust What are options for C++? 1. translate to utf16 ( https://github.com/simdutf/simdutf ) and use icu -- slow 2. boost text, https://github.com/tzlaine/text , also slow (because the author doesn't care or couldn't care), we made a lot of patches to make our library faster than lucene, but still this part is slower than icu for utf16 (icu for utf16 also very slow...)

You can find the corresponding assembly code in this repository. The main branch only contains implementations based on C++ with intrinsics.

The next big thing is making it LSP-compatible. All language servers must implement UTF-16 based character offsets, which is kinda unfortunate considering that files are much more likely to be stored in UTF-8 (I think?). I don't want to do the UTF-8 -> UTF-16 transcoding, so instead I'll use the excellent simdutf library to count how much code points a UTF-8 string would take if it was transcoded into UTF-16 — which is much faster than actual transcoding. So this is what I'm going to do this week — rewriting parsers to produce UTF-16 offsets + some final benchmarking. After that is done, I'll consider the "research" part of this project completed and will start writing an actual Markdown parser.

You can find the assembly code here: https://github.com/simdutf/simdutf/tree/clausecker The corresponding C++ code is in the main branch.

Or via an ultrafast simdutf.

Well it would depend on the specifics of the JSON file but eyeballing the stats at https://github.com/miloyip/nativejson-benchmark/tree/master seems to indicate that even on a 2015 MacBook the parsing proceeds using e.g. Configuru parser at several megabytes per second.

Maybe you need to try some other third party json library and see if it helps. This is a good list https://github.com/miloyip/nativejson-benchmark

Glancing at some benchmarks, RapidJSON stringifies at around 250MB/s on a single core (content-dependent, of course). Does not look like a bottleneck.

How does it compare to the immensely popular JSON for Modern C++ library by nlohmann? https://github.com/nlohmann/json

Also, you should add your library to the JSON benchmarks here: https://github.com/miloyip/nativejson-benchmark#parsing-time

I like your ideas, but they seem difficult to enforce. It assumes good faith on all sides. One of the biggest complaints about AI/ML research results: It is frequently hard/impossible to replicate the results.

One idea: The edge competitors can create a public (SourceHut?) project that runs various daily tests against themselves. This would similar to JSON library benchmarks. [1] Then allow each competitors to continuously tweak there settings to accomplish the task in the shortest amount of time.

Also: It would be nice to see a cost analysis. For years, IBM's DB2 was insanely fast if you could afford to pay outrageous hardware, software license, and consulting costs. I'm not in the edge business, but I guess there are some operators where you can just pay a lot more and get better performance -- if you really need it.

[1] https://github.com/miloyip/nativejson-benchmark

There's some useful benchmarks here. I found it while looking for stats on json-c vs parson, which I've used a fair amount.

If you looking for benchmarks to show in which cases your library is better than other 30 or so competitors, then see this repo https://github.com/miloyip/nativejson-benchmark

JSON data files from this project: https://github.com/miloyip/nativejson-benchmark

Such a shame, really. There is a ton fast json parsers there, like https://github.com/miloyip/nativejson-benchmark#parsing-time. And second issue is just hilarious: let's scan array millions of times, who needs hashmaps anyway?