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iopending(1m)                                   USER COMMANDS                                  iopending(1m)



NAME
       iopending - plot number of pending disk events. Uses DTrace.

SYNOPSIS
       iopending [-c] [-d device] [-f filename] [-m mount_point] [interval [count]]

DESCRIPTION
       This samples the number of disk events that are pending and plots a distribution graph. By doing this
       the "serialness" or "parallelness" of disk behaviour can be distinguished.  A  high  occurance  of  a
       pending value of more than 1 is an indication of saturation.

       Since  this  uses  DTrace,  only the root user or users with the dtrace_kernel privilege can run this
       command.

OPTIONS
       -c     clear screen

       -d device
              instance name to snoop (eg, dad0)

       -f filename
              full pathname of file to snoop

       -m mount_point
              mountpoint for filesystem to snoop

EXAMPLES
       Default output, print I/O summary every 1 second,
              # iopending


       Print 10 second samples,
              # iopending 10


       Print 12 x 5 second samples,
              # iopending 5 12


       Snoop events on the root filesystem only,
              # iopending -m /


FIELDS
       value  number of pending events, 0 == idle

       count  number of samples @ 1000 Hz

       load   1 min load average

       disk_r total disk read Kb for sample

       disk_w total disk write Kb for sample


IDEA
       Dr Rex di Bona


DOCUMENTATION
       See the DTraceToolkit for further documentation under the Docs directory. The DTraceToolkit docs  may
       include full worked examples with verbose descriptions explaining the output.

EXIT
       iopending will run forever until Ctrl-C is hit, or the specified count is reached.

AUTHOR
       Brendan Gregg [Sydney, Australia]

SEE ALSO
       iosnoop(1M), iotop(1M), dtrace(1M)




version 0.60                                    Nov 01, 2005                                   iopending(1m)