pt-ioprofile - Watch process IO and print a table of file and I/O activity.



pt-ioprofile [OPTIONS] [FILE]

pt-ioprofile does two things: 1) get lsof+strace for -s seconds, 2) aggregate the result. If you specify a FILE, then step 1) is not performed.


The following section is included to inform users about the potential risks, whether known or unknown, of using this tool. The two main categories of risks are those created by the nature of the tool (e.g. read-only tools vs. read-write tools) and those created by bugs.

pt-ioprofile is a read-only tool, so your data is not at risk. However, it works by attaching strace to the process using ptrace(), which will make it run very slowly until strace detaches. In addition to freezing the server, there is also some risk of the process crashing or performing badly after strace detaches from it, or indeed of strace not detaching cleanly and leaving the process in a sleeping state. As a result, this should be considered an intrusive tool, and should not be used on production servers unless you are comfortable with that.

At the time of this release, we know of no bugs that could cause serious harm to users.

The authoritative source for updated information is always the online issue tracking system. Issues that affect this tool will be marked as such. You can see a list of such issues at the following URL:

See also “BUGS” for more information on filing bugs and getting help.


pt-ioprofile uses strace and lsof to watch a process’s IO and print out a table of files and I/O activity. By default, it watches the mysqld process for 30 seconds. The output is like:

Tue Dec 27 15:33:57 PST 2011
Tracing process ID 1833
     total       read      write      lseek  ftruncate filename
  0.000150   0.000029   0.000068   0.000038   0.000015 /tmp/ibBE5opS

You probably need to run this tool as root.



short form: -a; type: string; default: sum

The aggregate function, either sum or avg.

If sum, then each cell will contain the sum of the values in it. If avg, then each cell will contain the average of the values in it.


short form: -c; type: string; default: times

The cell contents.

Valid values are:

=====  =======================
count  Count of I/O operations
sizes  Sizes of I/O operations
times  I/O operation timing

short form: -g; type: string; default: filename

The group-by item.

Valid values are:

=====     ======================================
all       Summarize into a single line of output
filename  One line of output per filename
pid       One line of output per process ID

Print help and exit.


short form: -p; type: int

The PID to profile, overrides --profile-process.


short form: -b; type: string; default: mysqld

The process name to profile.


type: int; default: 30

How long to profile.


type: string

Filename to save samples in; these can be used for later analysis.


Print the tool’s version and exit.


This tool does not use any environment variables.


This tool requires the Bourne shell (/bin/sh).


For a list of known bugs, see

Please report bugs at Include the following information in your bug report:

  • Complete command-line used to run the tool
  • Tool --version
  • MySQL version of all servers involved
  • Output from the tool including STDERR
  • Input files (log/dump/config files, etc.)

If possible, include debugging output by running the tool with PTDEBUG; see “ENVIRONMENT”.


Visit to download the latest release of Percona Toolkit. Or, get the latest release from the command line:




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Replace TOOL with the name of any tool.


Baron Schwartz


This tool is part of Percona Toolkit, a collection of advanced command-line tools developed by Percona for MySQL support and consulting. Percona Toolkit was forked from two projects in June, 2011: Maatkit and Aspersa. Those projects were created by Baron Schwartz and developed primarily by him and Daniel Nichter, both of whom are employed by Percona. Visit for more software developed by Percona.


pt-ioprofile 2.1.10

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