vfscount - Count VFS calls ("vfs_*"). Uses Linux eBPF/bcc.
This counts VFS calls. This can be useful for general workload characterization
of these operations.
This works by tracing all kernel functions beginning with "vfs_" using
dynamic tracing. This may match more functions than you are interested in
measuring: Edit the script to customize which functions to trace.
Since this uses BPF, only the root user can use this tool.
CONFIG_BPF and bcc.
- Count some VFS calls until Ctrl-C is hit:
- # vfscount
- Address of the instruction pointer that was traced (only
useful if the FUNC column is suspicious and you would like to double check
- Kernel function name
- Number of calls while tracing
This traces kernel vfs functions and maintains in-kernel counts, which are
asynchronously copied to user-space. While the rate of VFS operations can be
very high (>1M/sec), this is a relatively efficient way to trace these
events, and so the overhead is expected to be small for normal workloads.
Measure in a test environment, and if overheads are an issue, edit the script
to reduce the types of vfs functions traced (currently all beginning with
This is from bcc.
Also look in the bcc distribution for a companion _examples.txt file containing
example usage, output, and commentary for this tool.
Unstable - in development.