7b7a37c069
Summary: The new microbenchmarks, DBGetMergeOperandsInMemtable and DBGetMergeOperandsInSstFile, correspond to the two different LSMs tested: all data in one memtable and all data in one SST file, respectively. Both cases are parameterized by thread count (1 or 8) and merge operands per key (1, 32, or 1024). The SST file case is additionally parameterized by whether data is in block cache or mmap'd memory. Pull Request resolved: https://github.com/facebook/rocksdb/pull/9971 Test Plan: ``` $ TEST_TMPDIR=/dev/shm/db_basic_bench/ ./db_basic_bench --benchmark_filter=DBGetMergeOperands The number of inputs is very large. DBGet will be repeated at least 192 times. The number of inputs is very large. DBGet will be repeated at least 192 times. 2022-05-09T13:15:40-07:00 Running ./db_basic_bench Run on (36 X 2570.91 MHz CPU s) CPU Caches: L1 Data 32 KiB (x18) L1 Instruction 32 KiB (x18) L2 Unified 1024 KiB (x18) L3 Unified 25344 KiB (x1) Load Average: 4.50, 4.33, 4.37 ---------------------------------------------------------------------------------------------------------------------------- Benchmark Time CPU Iterations UserCounters... ---------------------------------------------------------------------------------------------------------------------------- DBGetMergeOperandsInMemtable/entries_per_key:1/threads:1 846 ns 846 ns 849893 db_size=0 DBGetMergeOperandsInMemtable/entries_per_key:32/threads:1 2436 ns 2436 ns 305779 db_size=0 DBGetMergeOperandsInMemtable/entries_per_key:1024/threads:1 77226 ns 77224 ns 8152 db_size=0 DBGetMergeOperandsInMemtable/entries_per_key:1/threads:8 116 ns 929 ns 779368 db_size=0 DBGetMergeOperandsInMemtable/entries_per_key:32/threads:8 330 ns 2644 ns 280824 db_size=0 DBGetMergeOperandsInMemtable/entries_per_key:1024/threads:8 12466 ns 99718 ns 7200 db_size=0 DBGetMergeOperandsInSstFile/entries_per_key:1/mmap:0/threads:1 1640 ns 1640 ns 461262 db_size=21.7826M DBGetMergeOperandsInSstFile/entries_per_key:1/mmap:1/threads:1 1693 ns 1693 ns 439936 db_size=21.7826M DBGetMergeOperandsInSstFile/entries_per_key:32/mmap:0/threads:1 3999 ns 3999 ns 172881 db_size=19.6981M DBGetMergeOperandsInSstFile/entries_per_key:32/mmap:1/threads:1 5544 ns 5543 ns 135657 db_size=19.6981M DBGetMergeOperandsInSstFile/entries_per_key:1024/mmap:0/threads:1 78767 ns 78761 ns 8395 db_size=19.6389M DBGetMergeOperandsInSstFile/entries_per_key:1024/mmap:1/threads:1 157242 ns 157238 ns 4495 db_size=19.6389M DBGetMergeOperandsInSstFile/entries_per_key:1/mmap:0/threads:8 231 ns 1848 ns 347768 db_size=21.7826M DBGetMergeOperandsInSstFile/entries_per_key:1/mmap:1/threads:8 214 ns 1715 ns 393312 db_size=21.7826M DBGetMergeOperandsInSstFile/entries_per_key:32/mmap:0/threads:8 596 ns 4767 ns 142088 db_size=19.6981M DBGetMergeOperandsInSstFile/entries_per_key:32/mmap:1/threads:8 720 ns 5757 ns 118200 db_size=19.6981M DBGetMergeOperandsInSstFile/entries_per_key:1024/mmap:0/threads:8 11613 ns 92460 ns 7344 db_size=19.6389M DBGetMergeOperandsInSstFile/entries_per_key:1024/mmap:1/threads:8 19989 ns 159908 ns 4440 db_size=19.6389M ``` Reviewed By: jay-zhuang Differential Revision: D36258861 Pulled By: ajkr fbshipit-source-id: 04b733e1cc3a4a70ed9baa894c50fdf96c0d6064 |
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| CMakeLists.txt | ||
| db_basic_bench.cc | ||
| README.md | ||
| ribbon_bench.cc | ||
RocksDB Micro-Benchmark
Overview
RocksDB micro-benchmark is a set of tests for benchmarking a single component or simple DB operations. The test artificially generates input data and executes the same operation with it to collect and report performance metrics. As it's focusing on testing a single, well-defined operation, the result is more precise and reproducible, which also has its limitation of not representing a real production use case. The test author needs to carefully design the microbench to represent its true purpose.
The tests are based on Google Benchmark library, which provides a standard framework for writing benchmarks.
How to Run
Prerequisite
Install the Google Benchmark version 1.6.0 or above.
Note: Google Benchmark 1.6.x is incompatible with previous versions like 1.5.x, please make sure you're using the newer version.
Build and Run
With Makefile:
$ DEBUG_LEVEL=0 make run_microbench
Or with cmake:
$ mkdir build && cd build && cmake .. -DCMAKE_BUILD_TYPE=Release -DWITH_BENCHMARK
$ make run_microbench
Note: Please run the benchmark code in release build.
Run Single Test
Example:
$ make db_basic_bench
$ ./db_basic_bench --benchmark_filter=<TEST_NAME>
Best Practices
* Use the Same Test Directory Setting as Unittest
Most of the Micro-benchmark tests use the same test directory setup as unittest, so it could be overridden by:
$ TEST_TMPDIR=/mydata/tmp/ ./db_basic_bench --benchmark_filter=<TEST_NAME>
Please also follow that when designing new tests.
* Avoid Using Debug API
Even though micro-benchmark is a test, avoid using internal Debug API like TEST_WaitForRun() which is designed for unittest. As benchmark tests are designed for release build, don't use any of that.
* Pay Attention to Local Optimization
As a micro-benchmark is focusing on a single component or area, make sure it is a key part for impacting the overall application performance.
The compiler might be able to optimize the code that not the same way as the whole application, and if the test data input is simple and small, it may be able to all cached in CPU memory, which is leading to a wrong metric. Take these into consideration when designing the tests.
* Names of user-defined counters/metrics has to be [A-Za-z0-9_]
It's a restriction of the metrics collecting and reporting system RocksDB is using internally. It will also help integrate with more systems.
* Minimize the Metrics Variation
Try reducing the test result variation, one way to check that is running the test multiple times and check the CV (Coefficient of Variation) reported by gbenchmark.
$ ./db_basic_bench --benchmark_filter=<TEST_NAME> --benchmark_repetitions=10
...
<TEST_NAME>_cv 3.2%
RocksDB has background compaction jobs which may cause the test result to vary a lot. If the micro-benchmark is not purposely testing the operation while compaction is in progress, it should wait for the compaction to finish (db_impl->WaitForCompact()) or disable auto-compaction.