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/bpftrace/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)

USER COMMANDS                                      2018-09-06                                     vfscount.bt(8)