---
name: "iopending"
section: "1m"
platform: "macos"
package: "dtrace"
version: "413"
release: "macOS 26.5"
platforms: ["macos"]
url: "https://new.carta.tech/iopending"
---

# iopending(1m)

plot number of pending disk events. Uses DTrace.

## 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)