iopending(1m) Mac OS X Manual Page

Mac Dev Center Mac OS X Reference Library General Mac OS X Man Pages

This manual page is for Mac OS X version 10.6.3

If you are running a different version of Mac OS X, view the documentation locally:

In Terminal, using the man(1) command

Reading manual pages

Manual pages are intended as a quick reference for people who already understand a technology.

For more information about the manual page format, see the manual page for manpages(5).
For more information about this technology, look for other documentation in the Apple Reference Library.
For general information about writing shell scripts, read Shell Scripting Primer.


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 users with root privileges 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)

Reporting Problems

The way to report a problem with this manual page depends on the type of problem:

Content errors: Report errors in the content of this documentation with the feedback links below.
Bug reports: Report bugs in the functionality of the described tool or API through Bug Reporter.
Formatting problems: Report formatting mistakes in the online version of these pages with the feedback links below.

Did this document help you?