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)