HDR histogram - aerospike/aerospike-benchmark GitHub Wiki

The HDR histograms are used to record both periodic and cumulative latency data. You can see the original repository for the HDR histogram here.

To enable periodic latency logging to stdout, pass the --latency flag to the benchmark tool, i.e.

target/benchmark --latency

To specify the latency percentiles to show, also pass the --percentiles flag followed by a comma-separated list of percentiles (i.e. between 0 and 100, exclusive) in ascending order. For example:

target/benchmark --latency --percentiles 50,80,90,99,99.9

To specify how often to report periodic latency data, pass the --outputPeriod flag followed by the number of seconds to wait between successive prints (must be a whole number greater than 0). The latency data shown will have been accumulated since the last time it was printed. For example:

target/benchmark --latency --outputPeriod 5

To enable tracing cumulative latency information, pass the --hdrHist flag to the benchmark tool followed by a directory in which to dump the cumulative latency logs. For example:

target/benchmark --hdrHist hdr_output

This will dump the traces in the hdr_output directory (which must already exist). The files created will depend on what type of workload is being executed. For workloads containing writes, two files will be made in the directory specified, write_<UTC_time>.hdrhist and write_<UTC_time>.txt, with the UTC time being the time at which the benchmark first began executing. For workloads containing reads, the same will be done in read_<UTC_time>.hdrhist and read_<UTC_time>.txt.

The format of the .hdrhist files is a base-64 encoded compressed binary form of the histogram.

The format of the .txt files is a four-column table of values, the percentiles at which those values occur, the total count of records accumulated at or below that value, and 1/(1-percentile). At the bottom of this file, it lists the mean, standard deviation, max, total count, total number of buckets, and total number of sub buckets.