NAME

       vfsstat - Statistics for some common VFS calls. Uses Linux eBPF/bcc.

SYNOPSIS

       vfsstat [interval [count]]

DESCRIPTION

       This  traces some common VFS calls and prints per-second summaries. This can be useful for
       general workload characterization, and looking for patterns in operation usage over time.

       This works by tracing some kernel vfs functions  using  dynamic  tracing,  and  will  need
       updating  to  match  any  changes  to  these functions. Edit the script to customize which
       functions are traced. Also see vfscount, which is more easily customized to trace multiple
       functions.

       Since this uses BPF, only the root user can use this tool.

REQUIREMENTS

       CONFIG_BPF and bcc.

EXAMPLES

       Print summaries each second:
              # vfsstat

       Print output every five seconds, three times:
              # vfsstat 5 3

FIELDS

       READ/s Number of vfs_read() calls as a per-second average.

       WRITE/s
              Number of vfs_write() calls as a per-second average.

       CREATE/s
              Number of vfs_create() calls as a per-second average.

       OPEN/s Number of vfs_open() calls as a per-second average.

       FSYNC/s
              Number of vfs_fsync() calls as a per-second average.

OVERHEAD

       This  traces  various  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.

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

       vfscount(8)