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1 # Benchmark Tools
3 ## compare_bench.py
5 The `compare_bench.py` utility which can be used to compare the result of benchmarks.
6 The program is invoked like:
8 ``` bash
9 $ compare_bench.py <old-benchmark> <new-benchmark> [benchmark options]...
10 ```
12 Where `<old-benchmark>` and `<new-benchmark>` either specify a benchmark executable file, or a JSON output file. The type of the input file is automatically detected. If a benchmark executable is specified then the benchmark is run to obtain the results. Otherwise the results are simply loaded from the output file.
14 `[benchmark options]` will be passed to the benchmarks invocations. They can be anything that binary accepts, be it either normal `--benchmark_*` parameters, or some custom parameters your binary takes.
16 The sample output using the JSON test files under `Inputs/` gives:
18 ``` bash
19 $ ./compare_bench.py ./gbench/Inputs/test1_run1.json ./gbench/Inputs/test1_run2.json
20 Comparing ./gbench/Inputs/test1_run1.json to ./gbench/Inputs/test1_run2.json
21 Benchmark Time CPU Time Old Time New CPU Old CPU New
22 -------------------------------------------------------------------------------------------------------------
23 BM_SameTimes +0.0000 +0.0000 10 10 10 10
24 BM_2xFaster -0.5000 -0.5000 50 25 50 25
25 BM_2xSlower +1.0000 +1.0000 50 100 50 100
26 BM_1PercentFaster -0.0100 -0.0100 100 99 100 99
27 BM_1PercentSlower +0.0100 +0.0100 100 101 100 101
28 BM_10PercentFaster -0.1000 -0.1000 100 90 100 90
29 BM_10PercentSlower +0.1000 +0.1000 100 110 100 110
30 BM_100xSlower +99.0000 +99.0000 100 10000 100 10000
31 BM_100xFaster -0.9900 -0.9900 10000 100 10000 100
32 BM_10PercentCPUToTime +0.1000 -0.1000 100 110 100 90
33 BM_ThirdFaster -0.3333 -0.3334 100 67 100 67
34 BM_BadTimeUnit -0.9000 +0.2000 0 0 0 1
35 ```
37 As you can note, the values in `Time` and `CPU` columns are calculated as `(new - old) / |old|`.
39 When a benchmark executable is run, the raw output from the benchmark is printed in real time to stdout. The sample output using `benchmark/basic_test` for both arguments looks like:
41 ```
42 ./compare_bench.py test/basic_test test/basic_test --benchmark_filter=BM_empty.*
43 RUNNING: test/basic_test --benchmark_filter=BM_empty.* --benchmark_out=/tmp/tmpN7LF3a
44 Run on (8 X 4000 MHz CPU s)
45 2017-11-07 23:28:36
46 ---------------------------------------------------------------------
47 Benchmark Time CPU Iterations
48 ---------------------------------------------------------------------
49 BM_empty 4 ns 4 ns 170178757
50 BM_empty/threads:8 1 ns 7 ns 103868920
51 BM_empty_stop_start 0 ns 0 ns 1000000000
52 BM_empty_stop_start/threads:8 0 ns 0 ns 1403031720
53 RUNNING: /test/basic_test --benchmark_filter=BM_empty.* --benchmark_out=/tmp/tmplvrIp8
54 Run on (8 X 4000 MHz CPU s)
55 2017-11-07 23:28:38
56 ---------------------------------------------------------------------
57 Benchmark Time CPU Iterations
58 ---------------------------------------------------------------------
59 BM_empty 4 ns 4 ns 169534855
60 BM_empty/threads:8 1 ns 7 ns 104188776
61 BM_empty_stop_start 0 ns 0 ns 1000000000
62 BM_empty_stop_start/threads:8 0 ns 0 ns 1404159424
63 Comparing ../build/test/basic_test to ../build/test/basic_test
64 Benchmark Time CPU Time Old Time New CPU Old CPU New
65 ---------------------------------------------------------------------------------------------------------------------
66 BM_empty -0.0048 -0.0049 4 4 4 4
67 BM_empty/threads:8 -0.0123 -0.0054 1 1 7 7
68 BM_empty_stop_start -0.0000 -0.0000 0 0 0 0
69 BM_empty_stop_start/threads:8 -0.0029 +0.0001 0 0 0 0
71 ```
73 As you can note, the values in `Time` and `CPU` columns are calculated as `(new - old) / |old|`.
74 Obviously this example doesn't give any useful output, but it's intended to show the output format when 'compare_bench.py' needs to run benchmarks.
76 ## compare.py
78 The `compare.py` can be used to compare the result of benchmarks.
79 There are three modes of operation:
81 1. Just compare two benchmarks, what `compare_bench.py` did.
82 The program is invoked like:
84 ``` bash
85 $ compare.py benchmarks <benchmark_baseline> <benchmark_contender> [benchmark options]...
86 ```
87 Where `<benchmark_baseline>` and `<benchmark_contender>` either specify a benchmark executable file, or a JSON output file. The type of the input file is automatically detected. If a benchmark executable is specified then the benchmark is run to obtain the results. Otherwise the results are simply loaded from the output file.
89 `[benchmark options]` will be passed to the benchmarks invocations. They can be anything that binary accepts, be it either normal `--benchmark_*` parameters, or some custom parameters your binary takes.
91 Example output:
92 ```
93 $ ./compare.py benchmarks ./a.out ./a.out
94 RUNNING: ./a.out --benchmark_out=/tmp/tmprBT5nW
95 Run on (8 X 4000 MHz CPU s)
96 2017-11-07 21:16:44
97 ------------------------------------------------------
98 Benchmark Time CPU Iterations
99 ------------------------------------------------------
100 BM_memcpy/8 36 ns 36 ns 19101577 211.669MB/s
101 BM_memcpy/64 76 ns 76 ns 9412571 800.199MB/s
102 BM_memcpy/512 84 ns 84 ns 8249070 5.64771GB/s
103 BM_memcpy/1024 116 ns 116 ns 6181763 8.19505GB/s
104 BM_memcpy/8192 643 ns 643 ns 1062855 11.8636GB/s
105 BM_copy/8 222 ns 222 ns 3137987 34.3772MB/s
106 BM_copy/64 1608 ns 1608 ns 432758 37.9501MB/s
107 BM_copy/512 12589 ns 12589 ns 54806 38.7867MB/s
108 BM_copy/1024 25169 ns 25169 ns 27713 38.8003MB/s
109 BM_copy/8192 201165 ns 201112 ns 3486 38.8466MB/s
110 RUNNING: ./a.out --benchmark_out=/tmp/tmpt1wwG_
111 Run on (8 X 4000 MHz CPU s)
112 2017-11-07 21:16:53
113 ------------------------------------------------------
114 Benchmark Time CPU Iterations
115 ------------------------------------------------------
116 BM_memcpy/8 36 ns 36 ns 19397903 211.255MB/s
117 BM_memcpy/64 73 ns 73 ns 9691174 839.635MB/s
118 BM_memcpy/512 85 ns 85 ns 8312329 5.60101GB/s
119 BM_memcpy/1024 118 ns 118 ns 6438774 8.11608GB/s
120 BM_memcpy/8192 656 ns 656 ns 1068644 11.6277GB/s
121 BM_copy/8 223 ns 223 ns 3146977 34.2338MB/s
122 BM_copy/64 1611 ns 1611 ns 435340 37.8751MB/s
123 BM_copy/512 12622 ns 12622 ns 54818 38.6844MB/s
124 BM_copy/1024 25257 ns 25239 ns 27779 38.6927MB/s
125 BM_copy/8192 205013 ns 205010 ns 3479 38.108MB/s
126 Comparing ./a.out to ./a.out
127 Benchmark Time CPU Time Old Time New CPU Old CPU New
128 ------------------------------------------------------------------------------------------------------
129 BM_memcpy/8 +0.0020 +0.0020 36 36 36 36
130 BM_memcpy/64 -0.0468 -0.0470 76 73 76 73
131 BM_memcpy/512 +0.0081 +0.0083 84 85 84 85
132 BM_memcpy/1024 +0.0098 +0.0097 116 118 116 118
133 BM_memcpy/8192 +0.0200 +0.0203 643 656 643 656
134 BM_copy/8 +0.0046 +0.0042 222 223 222 223
135 BM_copy/64 +0.0020 +0.0020 1608 1611 1608 1611
136 BM_copy/512 +0.0027 +0.0026 12589 12622 12589 12622
137 BM_copy/1024 +0.0035 +0.0028 25169 25257 25169 25239
138 BM_copy/8192 +0.0191 +0.0194 201165 205013 201112 205010
139 ```
141 What it does is for the every benchmark from the first run it looks for the benchmark with exactly the same name in the second run, and then compares the results. If the names differ, the benchmark is omitted from the diff.
142 As you can note, the values in `Time` and `CPU` columns are calculated as `(new - old) / |old|`.
144 2. Compare two different filters of one benchmark
145 The program is invoked like:
147 ``` bash
148 $ compare.py filters <benchmark> <filter_baseline> <filter_contender> [benchmark options]...
149 ```
150 Where `<benchmark>` either specify a benchmark executable file, or a JSON output file. The type of the input file is automatically detected. If a benchmark executable is specified then the benchmark is run to obtain the results. Otherwise the results are simply loaded from the output file.
152 Where `<filter_baseline>` and `<filter_contender>` are the same regex filters that you would pass to the `[--benchmark_filter=<regex>]` parameter of the benchmark binary.
154 `[benchmark options]` will be passed to the benchmarks invocations. They can be anything that binary accepts, be it either normal `--benchmark_*` parameters, or some custom parameters your binary takes.
156 Example output:
157 ```
158 $ ./compare.py filters ./a.out BM_memcpy BM_copy
159 RUNNING: ./a.out --benchmark_filter=BM_memcpy --benchmark_out=/tmp/tmpBWKk0k
160 Run on (8 X 4000 MHz CPU s)
161 2017-11-07 21:37:28
162 ------------------------------------------------------
163 Benchmark Time CPU Iterations
164 ------------------------------------------------------
165 BM_memcpy/8 36 ns 36 ns 17891491 211.215MB/s
166 BM_memcpy/64 74 ns 74 ns 9400999 825.646MB/s
167 BM_memcpy/512 87 ns 87 ns 8027453 5.46126GB/s
168 BM_memcpy/1024 111 ns 111 ns 6116853 8.5648GB/s
169 BM_memcpy/8192 657 ns 656 ns 1064679 11.6247GB/s
170 RUNNING: ./a.out --benchmark_filter=BM_copy --benchmark_out=/tmp/tmpAvWcOM
171 Run on (8 X 4000 MHz CPU s)
172 2017-11-07 21:37:33
173 ----------------------------------------------------
174 Benchmark Time CPU Iterations
175 ----------------------------------------------------
176 BM_copy/8 227 ns 227 ns 3038700 33.6264MB/s
177 BM_copy/64 1640 ns 1640 ns 426893 37.2154MB/s
178 BM_copy/512 12804 ns 12801 ns 55417 38.1444MB/s
179 BM_copy/1024 25409 ns 25407 ns 27516 38.4365MB/s
180 BM_copy/8192 202986 ns 202990 ns 3454 38.4871MB/s
181 Comparing BM_memcpy to BM_copy (from ./a.out)
182 Benchmark Time CPU Time Old Time New CPU Old CPU New
183 --------------------------------------------------------------------------------------------------------------------
184 [BM_memcpy vs. BM_copy]/8 +5.2829 +5.2812 36 227 36 227
185 [BM_memcpy vs. BM_copy]/64 +21.1719 +21.1856 74 1640 74 1640
186 [BM_memcpy vs. BM_copy]/512 +145.6487 +145.6097 87 12804 87 12801
187 [BM_memcpy vs. BM_copy]/1024 +227.1860 +227.1776 111 25409 111 25407
188 [BM_memcpy vs. BM_copy]/8192 +308.1664 +308.2898 657 202986 656 202990
189 ```
191 As you can see, it applies filter to the benchmarks, both when running the benchmark, and before doing the diff. And to make the diff work, the matches are replaced with some common string. Thus, you can compare two different benchmark families within one benchmark binary.
192 As you can note, the values in `Time` and `CPU` columns are calculated as `(new - old) / |old|`.
194 3. Compare filter one from benchmark one to filter two from benchmark two:
195 The program is invoked like:
197 ``` bash
198 $ compare.py filters <benchmark_baseline> <filter_baseline> <benchmark_contender> <filter_contender> [benchmark options]...
199 ```
201 Where `<benchmark_baseline>` and `<benchmark_contender>` either specify a benchmark executable file, or a JSON output file. The type of the input file is automatically detected. If a benchmark executable is specified then the benchmark is run to obtain the results. Otherwise the results are simply loaded from the output file.
203 Where `<filter_baseline>` and `<filter_contender>` are the same regex filters that you would pass to the `[--benchmark_filter=<regex>]` parameter of the benchmark binary.
205 `[benchmark options]` will be passed to the benchmarks invocations. They can be anything that binary accepts, be it either normal `--benchmark_*` parameters, or some custom parameters your binary takes.
207 Example output:
208 ```
209 $ ./compare.py benchmarksfiltered ./a.out BM_memcpy ./a.out BM_copy
210 RUNNING: ./a.out --benchmark_filter=BM_memcpy --benchmark_out=/tmp/tmp_FvbYg
211 Run on (8 X 4000 MHz CPU s)
212 2017-11-07 21:38:27
213 ------------------------------------------------------
214 Benchmark Time CPU Iterations
215 ------------------------------------------------------
216 BM_memcpy/8 37 ns 37 ns 18953482 204.118MB/s
217 BM_memcpy/64 74 ns 74 ns 9206578 828.245MB/s
218 BM_memcpy/512 91 ns 91 ns 8086195 5.25476GB/s
219 BM_memcpy/1024 120 ns 120 ns 5804513 7.95662GB/s
220 BM_memcpy/8192 664 ns 664 ns 1028363 11.4948GB/s
221 RUNNING: ./a.out --benchmark_filter=BM_copy --benchmark_out=/tmp/tmpDfL5iE
222 Run on (8 X 4000 MHz CPU s)
223 2017-11-07 21:38:32
224 ----------------------------------------------------
225 Benchmark Time CPU Iterations
226 ----------------------------------------------------
227 BM_copy/8 230 ns 230 ns 2985909 33.1161MB/s
228 BM_copy/64 1654 ns 1653 ns 419408 36.9137MB/s
229 BM_copy/512 13122 ns 13120 ns 53403 37.2156MB/s
230 BM_copy/1024 26679 ns 26666 ns 26575 36.6218MB/s
231 BM_copy/8192 215068 ns 215053 ns 3221 36.3283MB/s
232 Comparing BM_memcpy (from ./a.out) to BM_copy (from ./a.out)
233 Benchmark Time CPU Time Old Time New CPU Old CPU New
234 --------------------------------------------------------------------------------------------------------------------
235 [BM_memcpy vs. BM_copy]/8 +5.1649 +5.1637 37 230 37 230
236 [BM_memcpy vs. BM_copy]/64 +21.4352 +21.4374 74 1654 74 1653
237 [BM_memcpy vs. BM_copy]/512 +143.6022 +143.5865 91 13122 91 13120
238 [BM_memcpy vs. BM_copy]/1024 +221.5903 +221.4790 120 26679 120 26666
239 [BM_memcpy vs. BM_copy]/8192 +322.9059 +323.0096 664 215068 664 215053
240 ```
241 This is a mix of the previous two modes, two (potentially different) benchmark binaries are run, and a different filter is applied to each one.
242 As you can note, the values in `Time` and `CPU` columns are calculated as `(new - old) / |old|`.