60 lines
4.4 KiB
Markdown
60 lines
4.4 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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# 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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| 172.03 | 5,812,791.77 | 0.4% | 3,130.62 | 879.00 | 3.562 | 509.23 | 0.0% | 0.01 | `point reads`
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| 167.44 | 5,972,130.71 | 0.2% | 3,065.14 | 862.27 | 3.555 | 494.30 | 0.0% | 0.01 | `prefix reads`
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| 238.77 | 4,188,130.84 | 0.9% | 3,589.93 | 1,259.30 | 2.851 | 637.12 | 0.0% | 0.01 | `range reads`
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| 424.01 | 2,358,426.70 | 0.2% | 5,620.05 | 2,242.35 | 2.506 | 854.80 | 1.7% | 0.01 | `point writes`
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| 418.45 | 2,389,780.56 | 0.4% | 5,525.07 | 2,211.05 | 2.499 | 831.71 | 1.7% | 0.01 | `prefix writes`
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| 254.87 | 3,923,568.88 | 2.6% | 3,187.01 | 1,366.50 | 2.332 | 529.11 | 2.7% | 0.02 | `range writes`
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| 675.96 | 1,479,374.50 | 3.3% | 7,735.41 | 3,468.60 | 2.230 | 1,386.02 | 1.8% | 0.01 | `monotonic increasing point writes`
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| 137,986.20 | 7,247.10 | 0.6% | 789,752.33 | 699,462.00 | 1.129 | 144,824.14 | 0.0% | 0.01 | `worst case for radix tree`
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| 21.63 | 46,231,564.03 | 1.0% | 448.00 | 107.14 | 4.181 | 84.00 | 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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| 17.03 | 58,732,967.93 | 0.6% | 276.28 | 87.96 | 3.141 | 52.15 | 0.4% | 0.01 | `point reads`
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| 19.52 | 51,239,158.04 | 0.3% | 367.16 | 101.50 | 3.617 | 61.92 | 0.3% | 0.01 | `prefix reads`
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| 47.74 | 20,947,676.63 | 0.5% | 998.16 | 247.43 | 4.034 | 161.64 | 0.2% | 0.01 | `range reads`
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| 23.14 | 43,207,824.89 | 0.4% | 408.18 | 121.64 | 3.356 | 70.20 | 0.3% | 0.01 | `point writes`
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| 38.02 | 26,302,115.66 | 0.1% | 709.72 | 199.70 | 3.554 | 134.26 | 0.3% | 0.01 | `prefix writes`
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| 44.28 | 22,583,559.17 | 0.9% | 825.19 | 233.10 | 3.540 | 141.48 | 0.2% | 0.01 | `range writes`
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| 85.50 | 11,695,990.63 | 0.5% | 1,488.16 | 455.68 | 3.266 | 289.22 | 0.1% | 0.01 | `monotonic increasing point writes`
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| 338,388.50 | 2,955.18 | 3.3% | 4,097,087.00 | 1,809,996.00 | 2.264 | 759,645.00 | 0.0% | 0.01 | `worst case for radix tree`
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| 84.84 | 11,787,313.59 | 1.4% | 1,716.02 | 440.50 | 3.896 | 271.00 | 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: 4.47891 seconds, 364.05 MB/s, Add: 4.55599 seconds, 123.058 MB/s, Gc ratio: 37.1145%
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```
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## radix tree
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```
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Check: 1.05813 seconds, 1540.97 MB/s, Add: 1.32071 seconds, 424.508 MB/s, Gc ratio: 42.2067%
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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: 0.804094 seconds, 2027.81 MB/s, Add: 0.652952 seconds, 858.645 MB/s, Gc ratio: 35.3885%
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```
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