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29 lines
1.1 KiB
Markdown
29 lines
1.1 KiB
Markdown
# LongArray C++ Helpers
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This package contains helper functions for working with LongArray objects,
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as native C++ calls. The helpers are only built on Linux, and if they are absent,
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Java substitutes should be used instead.
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Library loading and access is available through the
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[NativeAlgos](java/nu/marginalia/NativeAlgos.java) class.
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Note that the C++ helpers are compiled with march=native by default, so they are not portable
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between different CPU architectures.
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This provides a speedup for some operations, especially when compared to using MemorySegment's
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get methods and not Unsafe.
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## Benchmarks
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JMH benchmark results for 64 bit quicksort N=2^10, 25 trials, graalvm 21.0.3:
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| Implementation | Throughput ops/s | Error p=99% |
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|----------------|------------------|-------------|
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| native | 114.877 | 4.216 |
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| unsafe | 98.443 | 2.723 |
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| memorysegment | 72.492 | 1.980 |
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Note that odds are stacked in favor of the native implementation
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since the dataset is fairly large, meaning the call overhead is
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less significant. For smaller datasets, the overhead of native
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calls may be a bigger factor. |