FS_USAGE(1)               BSD General Commands Manual              FS_USAGE(1)

NAME
     fs_usage -- report system calls and page faults related to filesystem
     activity in real-time

SYNOPSIS
     fs_usage [-e] [-w] [-f mode] [-b] [-t seconds] [-R rawfile [-S
              start_time] [-E end_time]] [pid | cmd [pid | cmd] ...]

DESCRIPTION
     The fs_usage utility presents an ongoing display of system call usage
     information pertaining to filesystem activity.  It requires root privi-
     leges due to the kernel tracing facility it uses to operate.  By default,
     the activity monitored includes all system processes except the running
     fs_usage process, Terminal, telnetd, telnet, sshd, rlogind, tcsh, csh,
     sh, and zsh.  These defaults can be overridden such that output is lim-
     ited to include or exclude a list of processes specified by the user.

     The output presented by fs_usage is formatted according to the size of
     your window.  A narrow window will display fewer columns of data.  Use a
     wide window for maximum data display.  You may override the window for-
     matting restrictions by forcing a wide display with the -w option.  In
     this case, the data displayed will wrap when the window is not wide
     enough.

     The options are as follows:

     -e      Specifying the -e option generates output that excludes sampling
             of the running fs_usage tool.  If a list of process IDs or com-
             mands is also given, then those processes are also excluded from
             the sampled output.

     -w      Specifying the -w option forces a wider, more detailed output,
             regardless of the window size.

     -f      Specifying the -f option turns on output filtering based on the
             mode provided.  Multiple filtering options can be specified.  By
             default, no output filtering occurs.  The supported modes are:

             network    Network-related events are displayed.

             filesys    Filesystem-related events are displayed.

             pathname   Pathname-related events are displayed.

             exec       Exec and spawn events are displayed.

             diskio     Disk I/O events are displayed.

             cachehit   In addition, show cache hits.

     -b      Specifying the -b option annotates disk I/O events with BootCache
             info (if available).

     -t seconds
             Specifies a run timeout in seconds.  fs_usage will run for no
             longer than the timeout specified.

     -R raw_file
             Specifies a raw trace file to process.

     -S start_time
             If -R is selected, specifies the start time in microseconds to
             begin processing entries from the raw trace file. Entries with
             timestamps before the specified start time will be skipped.

     -E end_time
             If -R is selected, specifies the ending time in microseconds to
             stop processing entries from the raw trace file.  Entries with
             timestamps beyond the specified ending time will be skipped.

     pid | cmd
             The sampled data can be limited to a list of process IDs or com-
             mands.  When a command name is given, all processes with that
             name will be sampled.  Using the -e option has the opposite
             effect, excluding sampled data relating to the given list of
             process IDs or commands.

     The data columns displayed are as follows:

     TIMESTAMP
             TOD when call occurred.  Wide mode will have microsecond granu-
             larity.

     CALL    The name of the network or filesystem related call, page-in,
             page-out, or physical disk access.

     FILE DESCRIPTOR
             Of the form F=x, x is a file descriptor.  Depending on the type
             of system call, this will be either an input value or a return
             value.

     BYTE COUNT
             Of the form B=x, x is the number of bytes requested by the call.

     [ERRNO]
             On error, the errno is displayed in brackets.

     PATHNAME
             Pathname of the file accessed (up to the last 28 bytes).

     FAULT ADDRESS
             Of the form A=0xnnnnnnnn, where 0xnnnnnnnn is the address being
             faulted.

     DISK BLOCK NUMBER
             Of the form D=0xnnnnnnnn, where 0xnnnnnnnn is the block number of
             the physical disk block being read or written.

     OFFSET  Of the form O=0xnnnnnnnn, where 0xnnnnnnnn is a file offset.

     SELECT RETURN
             Of the form S=x, x is the number of ready descriptors returned by
             the select() system call.  If S=0, the time limit expired.

     TIME INTERVAL(W)
             The elapsed time spent in the system call.  A `W' after the
             elapsed time indicates the process was scheduled out during this
             file activity.  In this case, the elapsed time includes the wait
             time.

     PROCESS NAME
             The process that made the system call.  Wide mode will append the
             thread id to the process name (i.e Mail.nnn).

SAMPLE USAGE
     fs_usage -w -f filesys Mail

     fs_usage will display file system related data for all instances of pro-
     cesses named Mail.  Maximum data output will be displayed in the window.

SEE ALSO
     dyld(1), latency(1), sc_usage(1), top(1)

Mac OS X                       November 7, 2002                       Mac OS X