iopending(1m) USER COMMANDS iopending(1m)
iopending - plot number of pending disk events. Uses DTrace.
iopending [-c] [-d device] [-f filename] [-m mount_point] [interval
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
-c clear screen
instance name to snoop (eg, dad0)
full pathname of file to snoop
mountpoint for filesystem to snoop
Default output, print I/O summary every 1 second,
Print 10 second samples,
# iopending 10
Print 12 x 5 second samples,
# iopending 5 12
Snoop events on the root filesystem only,
# iopending -m /
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
Dr Rex di Bona
See the DTraceToolkit for further documentation under the Docs directory.
The DTraceToolkit docs may include full worked examples with verbose
descriptions explaining the output.
iopending will run forever until Ctrl-C is hit, or the specified count is
Brendan Gregg [Sydney, Australia]
iosnoop(1M), iotop(1M), dtrace(1M)
version 0.60 November 1, 2005 iopending(1m)