Packages

rocksdb

2.1.0
3.1.2 3.1.1 3.1.0 3.0.0 2.6.2 2.6.1 retired 2.6.0 retired 2.5.0 2.4.1 2.4.0 2.3.0 2.2.0 2.1.0 2.0.0 1.9.0 1.8.0 1.7.0 1.6.0 1.5.1 1.5.0 1.4.0 1.3.2 1.3.1 1.3.0 1.2.0 1.1.1 1.1.0 1.0.0 0.26.2 0.26.1 0.26.0 0.25.0 0.24.0 0.23.3 0.23.2 0.23.1 0.23.0 0.22.0 0.21.0 0.20.1 0.20.0 0.19.0 0.18.0 0.17.0 0.16.0 0.15.0 0.14.0 0.13.1 0.13.0 0.12.0 0.11.0 0.10.0 0.9.1 0.9.0 0.8.2 0.8.1 0.8.0 0.7.1 0.7.0 0.6.4 0.6.3 0.6.2 0.6.1 0.6.0

RocksDB for Erlang

HexDocs

Current section

Files

Jump to
Readme
64 Versions
0 Dependencies
Dependants
Files
Activity
rocksdb deps snappy third_party benchmark docs perf_counters.md
Raw

deps/snappy/third_party/benchmark/docs/perf_counters.md 

<a name="perf-counters" />



# User-Requested Performance Counters



When running benchmarks, the user may choose to request collection of

performance counters. This may be useful in investigation scenarios - narrowing

down the cause of a regression; or verifying that the underlying cause of a

performance improvement matches expectations.



This feature is available if:



* The benchmark is run on an architecture featuring a Performance Monitoring

  Unit (PMU),

* The benchmark is compiled with support for collecting counters. Currently,

  this requires [libpfm](http://perfmon2.sourceforge.net/), which is built as a

  dependency via Bazel.



The feature does not require modifying benchmark code. Counter collection is

handled at the boundaries where timer collection is also handled. 



To opt-in:

* If using a Bazel build, add `--define pfm=1` to your build flags

* If using CMake:

  * Install `libpfm4-dev`, e.g. `apt-get install libpfm4-dev`.

  * Enable the CMake flag `BENCHMARK_ENABLE_LIBPFM` in `CMakeLists.txt`.



To use, pass a comma-separated list of counter names through the

`--benchmark_perf_counters` flag. The names are decoded through libpfm - meaning,

they are platform specific, but some (e.g. `CYCLES` or `INSTRUCTIONS`) are

mapped by libpfm to platform-specifics - see libpfm

[documentation](http://perfmon2.sourceforge.net/docs.html) for more details.



The counter values are reported back through the [User Counters](../README.md#custom-counters)

mechanism, meaning, they are available in all the formats (e.g. JSON) supported

by User Counters.