NAME

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

SYNOPSIS

       vfscount

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.

EXAMPLES

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

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)