62 lines
4.5 KiB
Markdown
62 lines
4.5 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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Compiler is `Ubuntu clang version 20.0.0 (++20241029082144+7544d3af0e28-1~exp1~20241029082307.506)`.
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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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| 159.65 | 6,263,576.52 | 1.6% | 2,972.36 | 820.37 | 3.623 | 504.59 | 0.0% | 0.01 | `point reads`
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| 156.32 | 6,397,320.65 | 0.7% | 2,913.62 | 806.87 | 3.611 | 490.19 | 0.0% | 0.01 | `prefix reads`
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| 229.18 | 4,363,293.65 | 1.2% | 3,541.05 | 1,219.75 | 2.903 | 629.33 | 0.0% | 0.01 | `range reads`
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| 363.37 | 2,752,026.30 | 0.3% | 5,273.63 | 1,951.54 | 2.702 | 851.66 | 1.7% | 0.01 | `point writes`
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| 364.99 | 2,739,787.02 | 0.3% | 5,250.92 | 1,958.54 | 2.681 | 839.24 | 1.7% | 0.01 | `prefix writes`
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| 242.26 | 4,127,796.58 | 2.9% | 3,117.33 | 1,304.41 | 2.390 | 541.07 | 2.8% | 0.02 | `range writes`
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| 562.48 | 1,777,855.27 | 0.8% | 7,305.21 | 3,034.34 | 2.408 | 1,329.30 | 1.3% | 0.01 | `monotonic increasing point writes`
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| 122,688.57 | 8,150.72 | 0.7% | 798,766.00 | 666,842.00 | 1.198 | 144,584.50 | 0.1% | 0.01 | `worst case for radix tree`
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| 41.71 | 23,976,459.34 | 1.7% | 885.00 | 219.17 | 4.038 | 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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| 12.83 | 77,947,334.88 | 0.8% | 247.13 | 63.80 | 3.873 | 32.64 | 0.6% | 0.01 | `point reads`
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| 14.73 | 67,908,470.74 | 0.1% | 299.99 | 73.66 | 4.073 | 42.50 | 0.5% | 0.01 | `prefix reads`
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| 35.63 | 28,066,165.78 | 0.1% | 782.70 | 178.49 | 4.385 | 106.65 | 0.2% | 0.01 | `range reads`
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| 20.00 | 49,993,123.62 | 0.1% | 376.83 | 100.50 | 3.749 | 50.05 | 0.5% | 0.01 | `point writes`
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| 38.04 | 26,287,266.49 | 0.1% | 665.86 | 191.21 | 3.482 | 100.41 | 0.4% | 0.01 | `prefix writes`
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| 40.48 | 24,703,557.31 | 1.3% | 732.80 | 204.36 | 3.586 | 111.26 | 0.2% | 0.01 | `range writes`
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| 81.01 | 12,343,591.64 | 1.4% | 1,551.57 | 409.23 | 3.791 | 292.66 | 0.1% | 0.01 | `monotonic increasing point writes`
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| 315,672.00 | 3,167.85 | 1.7% | 4,043,066.00 | 1,590,315.00 | 2.542 | 714,828.00 | 0.1% | 0.01 | `worst case for radix tree`
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| 114.81 | 8,710,164.86 | 0.7% | 2,178.00 | 578.69 | 3.764 | 345.00 | 0.0% | 0.01 | `create and destroy`
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# "Real data" test
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Point queries only, best of three runs. 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: 4.39702 seconds, 370.83 MB/s, Add: 4.50025 seconds, 124.583 MB/s, Gc ratio: 29.1333%, Peak idle memory: 5.51852e+06
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```
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## radix tree
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```
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Check: 0.975666 seconds, 1728.24 MB/s, Add: 1.19751 seconds, 480.444 MB/s, Gc ratio: 36.8478%, Peak idle memory: 2.39447e+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: 0.84256 seconds, 1935.23 MB/s, Add: 0.697204 seconds, 804.146 MB/s, Gc ratio: 35.4091%
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```
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