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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| 12.88 | 77,653,350.77 | 0.5% | 185.37 | 64.45 | 2.876 | 41.51 | 0.4% | 0.01 | `point reads`
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| 14.67 | 68,179,354.49 | 0.1% | 271.44 | 73.40 | 3.698 | 53.70 | 0.3% | 0.01 | `prefix reads`
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| 34.84 | 28,701,444.36 | 0.3% | 715.74 | 175.27 | 4.084 | 127.30 | 0.2% | 0.01 | `range reads`
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| 17.12 | 58,422,988.28 | 0.2% | 314.30 | 86.11 | 3.650 | 39.82 | 0.4% | 0.01 | `point writes`
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| 31.42 | 31,830,804.65 | 0.1% | 591.06 | 158.07 | 3.739 | 82.67 | 0.2% | 0.01 | `prefix writes`
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| 37.37 | 26,759,432.70 | 2.2% | 681.98 | 188.95 | 3.609 | 96.10 | 0.1% | 0.01 | `range writes`
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| 76.72 | 13,035,140.63 | 2.3% | 1,421.28 | 387.17 | 3.671 | 257.76 | 0.1% | 0.01 | `monotonic increasing point writes`
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| 297,452.00 | 3,361.89 | 0.9% | 3,508,083.00 | 1,500,834.67 | 2.337 | 727,525.33 | 0.1% | 0.01 | `worst case for radix tree`
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| 87.70 | 11,402,490.60 | 1.0% | 1,795.00 | 442.09 | 4.060 | 297.00 | 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: 0.953012 seconds, 1710.94 MB/s, Add: 1.30025 seconds, 431.188 MB/s, Gc ratio: 43.9816%, Peak idle memory: 2.28375e+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: 0.804094 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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