iopending(1) USER COMMANDS iopending(1)
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 direc-
tory. The DTraceToolkit docs may include full worked examples with ver-
bose 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(1)
Mac OS X 10.6 - Generated Thu Sep 17 20:07:55 CDT 2009