iopending(1m) USER COMMANDS iopending(1m)NAMEiopending - plot number of pending disk events. Uses DTrace.
SYNOPSISiopending [-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.
EXITiopending will run forever until Ctrl-C is hit, or the specified count
is reached.
AUTHOR
Brendan Gregg [Sydney, Australia]
SEE ALSOiosnoop(1M), iotop(1M), dtrace(1M)version 0.60 Nov 01, 2005 iopending(1m)