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1brc
1️⃣🐝🏎️ The One Billion Row Challenge -- A fun exploration of how quickly 1B rows from a text file can be aggregated with Java
1brc had SMT disabled [0]. (hyperthreading is an intel marketing name and trademark for their brand of smt, but the benchmark was run on an amd cpu)
[0] https://github.com/gunnarmorling/1brc/issues/189#issuecommen...
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CodeRabbit
CodeRabbit: AI Code Reviews for Developers. Revolutionize your code reviews with AI. CodeRabbit offers PR summaries, code walkthroughs, 1-click suggestions, and AST-based analysis. Boost productivity and code quality across all major languages with each PR.
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> GPU Hash Table?
How bad would performance have suffered if you sha256'd the lines to build the map? I'm going to guess "badly"?
Maybe something like this in CUDA: https://github.com/Cyan4973/xxHash ?
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1brc
C11 implementation of the 1 Billion Rows Challenge. 1️⃣🐝🏎️ Runs in ~1.6 seconds on my not-so-fast laptop CPU w/ 16GB RAM. (by dannyvankooten)
There are some good ideas for this type of problem here: https://github.com/dannyvankooten/1brc
After you deal with parsing and hashes, basically you are IO limited so mmap helps. A reasonable guess is that even for the optimal CUDA implementation, because there is no compute to speak of other than a hashmap, the starting of kernels and transfer of data to the GPU would likely add a noticeable bottleneck and make the optimal CUDA code slower than this pure C code.
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parallel-hashmap
A family of header-only, very fast and memory-friendly hashmap and btree containers.
Standard library maps/unordered_maps are themselves notoriously slow anyway. A sparse_hash_map from abseil or parallel-hashmaps[1] would be better.
[1] https://github.com/greg7mdp/parallel-hashmap