DTRACE_VFS(4)          FreeBSD Kernel Interfaces Manual          DTRACE_VFS(4)

NAME

     dtrace_vfs - a DTrace provider for Virtual File System

SYNOPSIS

     vfs:fplookup:function:name
     vfs:namecache:function:name
     vfs:namei:function:name
     vfs:vop:function:name

DESCRIPTION

     The DTrace vfs provider allows users to trace events in the VFS(9) layer,
     the kernel interface for file systems on FreeBSD.

     Run `dtrace -l -P vfs' to list all vfs probes.  Add -v to generate
     program stability reports, which contain information about the number of
     probe arguments and their types.

     The fplookup module defines a single probe,
     vfs:fplookup:lookup:done(struct nameidata *ndp, int line, bool
     status_code), that instruments the fast path lookup code in VFS(9).

     The namecache module provides probes related to the VFS(9) cache.
     Consult the source code in src/sys/kern/vfs_cache.c for more details.

     The namei module manages probes related to pathname translation and
     lookup operations.  Refer to namei(9) to learn more.

     The vop module contains probes related to the functions responsible for
     vnode(9) operations.

COMPATIBILITY

     This provider is specific to FreeBSD.

EXAMPLES

     Check what lookups failed to be handled in a lockless manner:

       # dtrace -n 'vfs:fplookup:lookup:done { @[arg1, arg2] = count(); }'

SEE ALSO

     dtrace(1), d(7), SDT(9), namei(9), VFS(9)

     Brendan Gregg and Jim Mauro, DTrace: Dynamic Tracing in Oracle Solaris,
     Mac OS X and FreeBSD, Prentice Hall,
     https://www.brendangregg.com/dtracebook/, pp. 335-351, 2011.

AUTHORS

     The FreeBSD vfs provider was written by Robert Watson
     <rwatson@FreeBSD.org>.

     This manual page was written by Mateusz Piotrowski <0mp@FreeBSD.org>.

FreeBSD 15.1-STABLE-HBSD       November 3, 2025                  DTRACE_VFS(4)