Andrew Noyes
ce23d3995c
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Tests / Release [clang,aarch64] total: 5446, passed: 5446
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Code Coverage #### Project Overview
No changes detected, that affect the code coverage.
* Line Coverage: 97.69% (3166/3241)
* Branch Coverage: 42.26% (19263/45584)
* Complexity Density: 0.00
* Lines of Code: 3241
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weaselab/conflict-set/pipeline/head This commit looks good
71 lines
4.6 KiB
Markdown
71 lines
4.6 KiB
Markdown
A data structure for optimistic concurrency control on ranges of bitwise-lexicographically-ordered keys.
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Intended as an alternative to FoundationDB's skip list.
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Hardware for all benchmarks is an AMD Ryzen 9 7900 with (2x32GB) 5600MT/s CL28-34-34-89 1.35V RAM.
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```
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$ clang++ --version
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Ubuntu clang version 20.0.0 (++20241119082716+7e85cb8a8a9d-1~exp1~20241119082825.551)
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Target: x86_64-pc-linux-gnu
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Thread model: posix
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InstalledDir: /usr/lib/llvm-20/bin
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```
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# Microbenchmark
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## Skip list
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| ns/op | op/s | err% | ins/op | cyc/op | IPC | bra/op | miss% | total | benchmark
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|--------------------:|--------------------:|--------:|----------------:|----------------:|-------:|---------------:|--------:|----------:|:----------
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| 169.16 | 5,911,582.44 | 0.0% | 3,014.03 | 855.12 | 3.525 | 504.59 | 0.0% | 2.02 | `point reads`
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| 167.17 | 5,981,796.19 | 0.0% | 2,954.16 | 845.14 | 3.495 | 490.17 | 0.0% | 2.00 | `prefix reads`
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| 250.44 | 3,992,954.35 | 0.1% | 3,592.41 | 1,265.18 | 2.839 | 629.31 | 0.0% | 2.99 | `range reads`
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| 467.10 | 2,140,846.36 | 0.0% | 4,450.57 | 2,488.36 | 1.789 | 707.92 | 2.1% | 5.62 | `point writes`
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| 465.18 | 2,149,723.11 | 0.2% | 4,410.22 | 2,474.92 | 1.782 | 694.74 | 2.1% | 5.55 | `prefix writes`
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| 297.45 | 3,361,954.05 | 0.1% | 2,315.38 | 1,581.64 | 1.464 | 396.69 | 3.3% | 3.57 | `range writes`
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| 476.56 | 2,098,370.82 | 1.0% | 6,999.33 | 2,492.26 | 2.808 | 1,251.74 | 1.3% | 0.06 | `monotonic increasing point writes`
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| 129,455.00 | 7,724.69 | 1.0% | 807,446.67 | 698,559.40 | 1.156 | 144,584.60 | 0.8% | 0.01 | `worst case for radix tree`
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| 44.67 | 22,384,996.63 | 0.5% | 902.00 | 235.18 | 3.835 | 132.00 | 0.0% | 0.01 | `create and destroy`
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## Radix tree (this implementation)
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| ns/op | op/s | err% | ins/op | cyc/op | IPC | bra/op | miss% | total | benchmark
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|--------------------:|--------------------:|--------:|----------------:|----------------:|-------:|---------------:|--------:|----------:|:----------
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| 14.11 | 70,857,435.19 | 0.1% | 247.13 | 71.03 | 3.479 | 32.64 | 0.8% | 0.17 | `point reads`
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| 15.63 | 63,997,306.79 | 0.0% | 299.99 | 78.59 | 3.817 | 42.50 | 0.4% | 0.19 | `prefix reads`
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| 36.24 | 27,590,266.59 | 0.1% | 782.70 | 182.21 | 4.296 | 106.65 | 0.2% | 0.43 | `range reads`
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| 22.72 | 44,004,627.40 | 0.1% | 376.04 | 114.33 | 3.289 | 49.97 | 0.8% | 0.27 | `point writes`
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| 40.83 | 24,494,110.04 | 0.0% | 666.07 | 205.35 | 3.244 | 101.33 | 0.3% | 0.49 | `prefix writes`
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| 43.45 | 23,016,324.00 | 0.0% | 732.33 | 218.41 | 3.353 | 111.64 | 0.1% | 0.53 | `range writes`
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| 81.46 | 12,276,650.63 | 3.6% | 1,458.85 | 411.52 | 3.545 | 280.42 | 0.1% | 0.01 | `monotonic increasing point writes`
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| 314,217.00 | 3,182.51 | 1.2% | 4,043,063.50 | 1,593,715.00 | 2.537 | 714,828.00 | 0.1% | 0.01 | `worst case for radix tree`
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| 106.79 | 9,364,602.60 | 0.5% | 2,046.00 | 539.75 | 3.791 | 329.00 | 0.0% | 0.01 | `create and destroy`
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# "Real data" test
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Point queries only. Gc ratio is the ratio of time spent doing garbage collection to time spent adding writes or doing garbage collection. Lower is better.
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## skip list
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```
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Check: 4.62434 seconds, 364.633 MB/s, Add: 3.90399 seconds, 147.371 MB/s, Gc ratio: 33.6898%, Peak idle memory: 5.61007e+06
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```
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## radix tree
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```
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Check: 0.956689 seconds, 1762.52 MB/s, Add: 1.35744 seconds, 423.84 MB/s, Gc ratio: 35.0946%, Peak idle memory: 2.32922e+06
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```
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## hash table
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(The hash table implementation doesn't work on range queries, and its purpose is to provide an idea of how fast point queries can be)
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```
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Check: 0.799863 seconds, 2108.09 MB/s, Add: 0.667736 seconds, 861.621 MB/s, Gc ratio: 35.0666%, Peak idle memory: 0
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```
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