bdevperf is an SPDK application used for performance testing of block devices (bdevs) exposed by the SPDK bdev layer. It is an alternative to the SPDK bdev fio plugin for benchmarking SPDK bdevs. In some cases, bdevperf can provide lower overhead than the fio plugin, resulting in better performance and efficiency for tests using a limited number of CPU cores.
bdevperf exposes command line interface that allows to specify SPDK framework options as well as testing options. bdevperf also supports a configuration file format similar to FIO. It allows user to create jobs parameterized by filename, cpumask, blocksize, queuesize, etc.
bdevperf's config file format is similar to FIO.
Below is an example config file that uses all available parameters:
Jobs [A] [B] or [C], inherit default values from [global] section residing above them. So in the example, job [A] inherits filename value and uses both Malloc0 and Malloc1 bdevs as targets, job [B] overrides its filename value and uses Malloc1 and job [C] inherits value Malloc0 for its filename.
Interaction with CLI arguments is not the same as in FIO however. If bdevperf receives CLI argument, it overrides values of corresponding parameter for all [global] sections of config file. So if example config is used, specifying -q argument will make jobs [A] and [B] use its value.
Below is a full list of supported parameters with descriptions.
| Param | Default | Description |
|---|---|---|
| filename | Bdevs to use, separated by ":" | |
| cpumask | Maximum available | CPU mask. Format is defined at CPU mask |
| bs | Block size (io size) | |
| iodepth | Queue depth | |
| rwmixread | 50 | Percentage of a mixed workload that should be reads |
| offset | 0 | Start I/O at the provided offset on the bdev |
| length | 100% of bdev size | End I/O at offset+length on the bdev |
| rw | Type of I/O pattern |
Available rw types:
bdevperf supports delivering test results in JSON format via the bdevperf.py perform_tests RPC command. This feature allows users to programmatically parse and analyze test results.
To enable JSON output, use the bdevperf.py perform_tests RPC command. The JSON response includes detailed test results for each job and a summary of the test execution. Below is an example of how to trigger a test and retrieve results in JSON format:
The JSON response consists of two main sections:
job: The name of the job (e.g., Malloc0).core_mask: The CPU core mask used for the job.workload: The type of workload (e.g., write).status: The status of the test.finished - the test completed successfully.failed - the test encountered an error.terminated - the test was interrupted (e.g., via SIGINT or Ctrl-C).queue_depth: The queue depth used for the test.io_size: The I/O size in bytes.runtime: The test runtime in seconds.iops: The I/O operations per second achieved.mibps: The throughput in MiB/s.io_failed: The number of failed I/O operations.io_timeout: The number of timed-out I/O operations.avg_latency_us: The average latency in microseconds.min_latency_us: The minimum latency in microseconds.max_latency_us: The maximum latency in microseconds.bdevperf was run with 0xFF mask, but only 2 cores were used).