bitesize.d(1m)

bitesize.d1m

Analyse disk i/o size by process. uses dtrace.

Usage

bitesize.d

Overview

This produces a report for the size of disk events caused by processes. These are the disk events sent by the block I/O driver.

If applications must use the disks, we generally prefer they do so sequentially with large I/O sizes, or larger "bites".

Since this uses DTrace, only users with root privileges can run this command.

Examples

Sample until Ctrl-C is hit then print report,

# bitesize.d

Fields

PID

process ID

CMD

command and argument list

value

size in bytes

count

number of I/O operations

Notes

The application may be requesting smaller sized operations, which are being rounded up to the nearest sector size or UFS block size.

To analyse what the application is requesting, DTraceToolkit programs such as Proc/fddist may help.

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

bitesize.d will sample until Ctrl-C is hit.

Releases

115 releases since Mac OS X 10.5; the text changed 1 time.

  1. 10.5–10.5.8
  2. 10.6–26.5

Author

Brendan Gregg [Sydney, Australia]

From dtrace 413 in macOS 26.5. Parsed by carta from the page's man source.