How to Get I/O Information Per Process Using Iopp

Iopp is a custom tool to go through the Linux process table to get I/O statistics per process. It is open source and can be downloaded from here.

In this article I will show how you can install and use the iopp to get the I/O operations per-process.

Install Iopp

You can install iopp from its source using git command as shown below:

# git clone git://git.postgresql.org/git/~markwkm/iopp.git
# cd iopp
# cmake CMakeLists.txt
# make

Finally install it.

# make install DESTDIR=/usr
[100%] Built target iopp
Install the project...
-- Install configuration: ""
-- Installing /usr/bin/iopp
-- Installing /usr/share/man/man8/iopp.8

Iopp will be installed into /user/bin.

After installing iopp lets see it all parameters:

# iopp -h
usage: iopp -h|--help
usage: iopp [-ci] [-k|-m] [delay [count]]
-c, --command display full command line
-h, --help display help
-i, --idle hides idle processes
-k, --kilobytes display data in kilobytes
-m, --megabytes display data in megabytes
-u, --human-readable display data in kilo-, mega-, or giga-bytes

Example

# iopp -i -k 5
  pid    rchar    wchar    syscr    syscw      rkb      wkb     cwkb command
 4912        2        1        0        0        0        0        0 dbus-daemon
 5713        0        1        0        0        0        0        0 hald
 5717       17        0        0        0        0        0        0 hald-runner
 5932        0        2        0        0        0        0        0 NetworkManager
22101       94       28        0        0        0        0        0 Xorg
22238        4        4        0        0        0        0        0 pulseaudio
22684       29       55        1        0        0        0        0 firefox
26860        0       43        0        0        0        0        0 gnome-terminal

Where;

• pid: The process id.
• rchar: The number of bytes which this task has caused to be read from storage.
• wchar: The number of bytes which this task has caused, or shall cause to be written to disk.
• syscr: Count of the number of read I/O operations.
• syscw: Count of the number of write I/O operations.
• rbytes rkb rmb reads: Count of the number of bytes which this process really did cause to be fetched from the storage layer.
• wbytes wkb wmb writes: Count of the number of bytes which this process really did cause to be sent to the storage layer.
• cwbytes cwkb cwmb cwrites: The number of bytes which this process caused to not happen, by truncating pagecache.
• command: Filename of the executable.