NAME

       vfscount.bt - Count VFS calls ("vfs_*"). Uses bpftrace/eBPF.

SYNOPSIS

       vfscount.bt

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 bpftrace.

EXAMPLES

       Count all VFS calls until Ctrl-C is hit:
              # vfscount.bt

FIELDS

       1st    Kernel function name (in @[])

       2nd    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 bpftrace.

              https://github.com/iovisor/bpftrace

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

       This is a bpftrace version of the bcc tool of the same name. The bcc tool may provide more
       options and customizations.

              https://github.com/iovisor/bcc

OS

       Linux

STABILITY

       Unstable - in development.

AUTHOR

       Brendan Gregg

SEE ALSO

       vfsstat.bt(8)