bitcoin/doc/benchmarking.md
Martin Ankerl 78c312c983 Replace current benchmarking framework with nanobench
This replaces the current benchmarking framework with nanobench [1], an
MIT licensed single-header benchmarking library, of which I am the
autor. This has in my opinion several advantages, especially on Linux:

* fast: Running all benchmarks takes ~6 seconds instead of 4m13s on
  an Intel i7-8700 CPU @ 3.20GHz.

* accurate: I ran e.g. the benchmark for SipHash_32b 10 times and
  calculate standard deviation / mean = coefficient of variation:

  * 0.57% CV for old benchmarking framework
  * 0.20% CV for nanobench

  So the benchmark results with nanobench seem to vary less than with
  the old framework.

* It automatically determines runtime based on clock precision, no need
  to specify number of evaluations.

* measure instructions, cycles, branches, instructions per cycle,
  branch misses (only Linux, when performance counters are available)

* output in markdown table format.

* Warn about unstable environment (frequency scaling, turbo, ...)

* For better profiling, it is possible to set the environment variable
  NANOBENCH_ENDLESS to force endless running of a particular benchmark
  without the need to recompile. This makes it to e.g. run "perf top"
  and look at hotspots.

Here is an example copy & pasted from the terminal output:

|             ns/byte |              byte/s |    err% |        ins/byte |        cyc/byte |    IPC |       bra/byte |   miss% |     total | benchmark
|--------------------:|--------------------:|--------:|----------------:|----------------:|-------:|---------------:|--------:|----------:|:----------
|                2.52 |      396,529,415.94 |    0.6% |           25.42 |            8.02 |  3.169 |           0.06 |    0.0% |      0.03 | `bench/crypto_hash.cpp RIPEMD160`
|                1.87 |      535,161,444.83 |    0.3% |           21.36 |            5.95 |  3.589 |           0.06 |    0.0% |      0.02 | `bench/crypto_hash.cpp SHA1`
|                3.22 |      310,344,174.79 |    1.1% |           36.80 |           10.22 |  3.601 |           0.09 |    0.0% |      0.04 | `bench/crypto_hash.cpp SHA256`
|                2.01 |      496,375,796.23 |    0.0% |           18.72 |            6.43 |  2.911 |           0.01 |    1.0% |      0.00 | `bench/crypto_hash.cpp SHA256D64_1024`
|                7.23 |      138,263,519.35 |    0.1% |           82.66 |           23.11 |  3.577 |           1.63 |    0.1% |      0.00 | `bench/crypto_hash.cpp SHA256_32b`
|                3.04 |      328,780,166.40 |    0.3% |           35.82 |            9.69 |  3.696 |           0.03 |    0.0% |      0.03 | `bench/crypto_hash.cpp SHA512`

[1] https://github.com/martinus/nanobench

* Adds support for asymptotes

  This adds support to calculate asymptotic complexity of a benchmark.
  This is similar to #17375, but currently only one asymptote is
  supported, and I have added support in the benchmark `ComplexMemPool`
  as an example.

  Usage is e.g. like this:

  ```
  ./bench_bitcoin -filter=ComplexMemPool -asymptote=25,50,100,200,400,600,800
  ```

  This runs the benchmark `ComplexMemPool` several times but with
  different complexityN settings. The benchmark can extract that number
  and use it accordingly. Here, it's used for `childTxs`. The output is
  this:

  | complexityN |               ns/op |                op/s |    err% |          ins/op |          cyc/op |    IPC |     total | benchmark
  |------------:|--------------------:|--------------------:|--------:|----------------:|----------------:|-------:|----------:|:----------
  |          25 |        1,064,241.00 |              939.64 |    1.4% |    3,960,279.00 |    2,829,708.00 |  1.400 |      0.01 | `ComplexMemPool`
  |          50 |        1,579,530.00 |              633.10 |    1.0% |    6,231,810.00 |    4,412,674.00 |  1.412 |      0.02 | `ComplexMemPool`
  |         100 |        4,022,774.00 |              248.58 |    0.6% |   16,544,406.00 |   11,889,535.00 |  1.392 |      0.04 | `ComplexMemPool`
  |         200 |       15,390,986.00 |               64.97 |    0.2% |   63,904,254.00 |   47,731,705.00 |  1.339 |      0.17 | `ComplexMemPool`
  |         400 |       69,394,711.00 |               14.41 |    0.1% |  272,602,461.00 |  219,014,691.00 |  1.245 |      0.76 | `ComplexMemPool`
  |         600 |      168,977,165.00 |                5.92 |    0.1% |  639,108,082.00 |  535,316,887.00 |  1.194 |      1.86 | `ComplexMemPool`
  |         800 |      310,109,077.00 |                3.22 |    0.1% |1,149,134,246.00 |  984,620,812.00 |  1.167 |      3.41 | `ComplexMemPool`

  |   coefficient |   err% | complexity
  |--------------:|-------:|------------
  |   4.78486e-07 |   4.5% | O(n^2)
  |   6.38557e-10 |  21.7% | O(n^3)
  |   3.42338e-05 |  38.0% | O(n log n)
  |   0.000313914 |  46.9% | O(n)
  |     0.0129823 | 114.4% | O(log n)
  |     0.0815055 | 133.8% | O(1)

  The best fitting curve is O(n^2), so the algorithm seems to scale
  quadratic with `childTxs` in the range 25 to 800.
2020-06-13 12:24:18 +02:00

1.5 KiB

Benchmarking

Bitcoin Core has an internal benchmarking framework, with benchmarks for cryptographic algorithms (e.g. SHA1, SHA256, SHA512, RIPEMD160, Poly1305, ChaCha20), rolling bloom filter, coins selection, thread queue, wallet balance.

Running

For benchmarks purposes you only need to compile bitcoin_bench. Beware of configuring without --enable-debug as this would impact benchmarking by unlatching log printers and lock analysis.

make -C src bitcoin_bench

After compiling bitcoin-core, the benchmarks can be run with:

src/bench/bench_bitcoin

The output will look similar to:

|             ns/byte |              byte/s | error % | benchmark
|--------------------:|--------------------:|--------:|:----------------------------------------------
|               64.13 |       15,592,356.01 |    0.1% | `Base58CheckEncode`
|               24.56 |       40,722,672.68 |    0.2% | `Base58Decode`
...

Help

src/bench/bench_bitcoin --help

To print options like scaling factor or per-benchmark filter.

Notes

More benchmarks are needed for, in no particular order:

  • Script Validation
  • Coins database
  • Memory pool
  • Cuckoo Cache
  • P2P throughput

Going Further

To monitor Bitcoin Core performance more in depth (like reindex or IBD): https://github.com/chaincodelabs/bitcoinperf

To generate Flame Graphs for Bitcoin Core: https://github.com/eklitzke/bitcoin/blob/flamegraphs/doc/flamegraphs.md