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

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

SYNOPSIS
       iiooppeennddiinngg  [-c]  [-d  device]  [-f filename] [-m mountpoint] [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
       dtracekernel privilege can run this command.

OOPPTTIIOONNSS
       -c     clear screen

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

       -f filename
              full pathname of file to snoop

       -m mountpoint
              mountpoint for filesystem to snoop

EEXXAAMMPPLLEESS
       Default output, print I/O summary every 1 second,
              # iiooppeennddiinngg


       Print 10 second samples,
              # iiooppeennddiinngg 10


       Print 12 x 5 second samples,
              # iiooppeennddiinngg 5 12


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


FFIIEELLDDSS
       value  number of pending events, 0 == idle

       count  number of samples @ 1000 Hz

       load   1 min load average

       diskr total disk read Kb for sample

       diskw total disk write Kb for sample


IIDDEEAA
       Dr Rex di Bona


DDOOCCUUMMEENNTTAATTIIOONN
       See the DTraceToolkit for further documentation under the  Docs  direc-
       tory. The DTraceToolkit docs may include full worked examples with ver-
       bose descriptions explaining the output.

EEXXIITT
       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)