Mark Callaghan d583d23d86 Avoid seed reuse when --benchmarks has more than one test (#9733)
Summary:
When --benchmarks has more than one test then the threads in one benchmark
will use the same set of seeds as the threads in the previous benchmark.
This diff fixe that.

This fixes https://github.com/facebook/rocksdb/issues/9632

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9733

Test Plan:
For this command line the block cache is 8GB, so it caches at most 1024 8KB blocks. Note that without
this diff the second run of readrandom has a much better response time because seed reuse means the
second run reads the same 1000 blocks as the first run and they are cached at that point. But with
this diff that does not happen.

./db_bench --benchmarks=fillseq,flush,compact0,waitforcompaction,levelstats,readrandom,readrandom --compression_type=zlib --num=10000000 --reads=1000 --block_size=8192

...

```
Level Files Size(MB)
--------------------
  0        0        0
  1       11      238
  2        9      253
  3        0        0
  4        0        0
  5        0        0
  6        0        0
```

 --- perf results without this diff

DB path: [/tmp/rocksdbtest-2260/dbbench]
readrandom   :      46.212 micros/op 21618 ops/sec;    2.4 MB/s (1000 of 1000 found)

DB path: [/tmp/rocksdbtest-2260/dbbench]
readrandom   :      21.963 micros/op 45450 ops/sec;    5.0 MB/s (1000 of 1000 found)

 --- perf results with this diff

DB path: [/tmp/rocksdbtest-2260/dbbench]
readrandom   :      47.213 micros/op 21126 ops/sec;    2.3 MB/s (1000 of 1000 found)

DB path: [/tmp/rocksdbtest-2260/dbbench]
readrandom   :      42.880 micros/op 23299 ops/sec;    2.6 MB/s (1000 of 1000 found)

Reviewed By: jay-zhuang

Differential Revision: D35089763

Pulled By: mdcallag

fbshipit-source-id: 1b50143a07afe876b8c8e5fa50dd94a8ce57fc6b
2022-03-24 08:57:48 -07:00
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RocksDB: A Persistent Key-Value Store for Flash and RAM Storage

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RocksDB is developed and maintained by Facebook Database Engineering Team. It is built on earlier work on LevelDB by Sanjay Ghemawat (sanjay@google.com) and Jeff Dean (jeff@google.com)

This code is a library that forms the core building block for a fast key-value server, especially suited for storing data on flash drives. It has a Log-Structured-Merge-Database (LSM) design with flexible tradeoffs between Write-Amplification-Factor (WAF), Read-Amplification-Factor (RAF) and Space-Amplification-Factor (SAF). It has multi-threaded compactions, making it especially suitable for storing multiple terabytes of data in a single database.

Start with example usage here: https://github.com/facebook/rocksdb/tree/main/examples

See the github wiki for more explanation.

The public interface is in include/. Callers should not include or rely on the details of any other header files in this package. Those internal APIs may be changed without warning.

Questions and discussions are welcome on the RocksDB Developers Public Facebook group and email list on Google Groups.

License

RocksDB is dual-licensed under both the GPLv2 (found in the COPYING file in the root directory) and Apache 2.0 License (found in the LICENSE.Apache file in the root directory). You may select, at your option, one of the above-listed licenses.

Description
A library that provides an embeddable, persistent key-value store for fast storage.
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