Limiting I/O usage by an application

Introduction link

Want to know why your load average is so high? Run this command to see what processes are on the run queue. Runnable processes have a status of “R”, and commands waiting on I/O have a status of “D”.

Once found, you may need to reduce its I/O requests, so we’ll use ionice.

Get I/O apps link

To get the biggest I/O consuming applications:

  ps -eo stat,pid,user,command 
  

On some older versions of Linux may require -emo instead of -eo.

And on Solaris:

  ps -aefL -o s -o user -o comm 
  

Ionice link

ionice limits process I/O, to keep it from swamping the system (Linux)

This command is somewhat similar to ’nice’, but constrains I/O usage rather than CPU usage. In particular, the ‘-c3’ flag tells the OS to only allow the process to do I/O when nothing else is pending. This dramatically increases the responsiveness of the rest of the system if the process is doing heavy I/O.

There’s also a ‘-p’ flag, to set the priority of an already-running process.

  ionice -c3 find /