vfscount(8)

NAME
vfscount - Count VFS calls ("vfs_*"). Uses Linux eBPF/bcc.

SYNOPSIS
vfscount [duration]

DESCRIPTION
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.

REQUIREMENTS
CONFIG_BPF and bcc.

OPTIONS

duration
    duration of the trace in seconds.

EXAMPLES

Count some VFS calls until Ctrl-C is hit:
    # vfscount

Count some VFS calls in ten seconds
    # vfscount 10

FIELDS

ADDR
    Address of the instruction pointer that was traced (only useful if the FUNC column is suspicious and you would like to double check the translation).

FUNC
    Kernel function name

COUNT
    Number of calls while tracing

OVERHEAD
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 "vfs_").

SOURCE
This is from bcc.

    https://github.com/iovisor/bcc

Also look in the bcc distribution for a companion _examples.txt file containing example usage, output, and commentary for this tool.

OS
Linux

STABILITY
Unstable - in development.

AUTHOR
Brendan Gregg

SEE ALSO
vfsstat(8)