Thursday, January 30, 2014

Lots of ext4-dio-unwrit processes in the server.

Issue

  • There are a lot of processes with the name ext4-dio-unwrit running on the system.
  • What are those processes?
  • Why so many ext4-dio-unwrit processes?
In RHEL 5.x and later you can see these processes are running. 

Root Cause

ext4-dio-unwrit processes are workqueues statically created at mount time of the filesystem, one workqueue per-cpu for each filesystem.
at