ureadahead trying to read entire filesystem

[Adam Collard]

MAAS Version 2.1.1+bzr5544-0ubuntu1 (16.04.1), deploying Ubuntu 16.04.1

As shown in bug 1635560 and specifically in https://pastebin.canonical.com/171385/ during deployment, ureadahead (sometimes?) tries to index the whole filesystem, complaining about all of the relative paths.

These are the log messages immediately before the spamminess:

Nov 22 08:32:32 faraday systemd[1]: Starting Stop ureadahead data collection...
Nov 22 08:32:32 faraday systemd[1]: Stopping Read required files in advance...
Nov 22 08:32:32 faraday systemd[1]: Started Stop ureadahead data collection.

The ureadahead lines are responsible for the vast majority of the installation log

⟫ cat faraday-installation-log | wc -l
78777
⟫ grep ureadahead faraday-installation-log | wc -l
76799

[Andres Rodriguez (andreserl)]

MAAS doesn't really do anything with ureadahead nor curtin does. However, by looking at the logs I've found this:

Nov 22 08:31:25 faraday systemd[1]: Started Stop ureadahead data collection 45s after completed startup.
[...]
Nov 22 08:31:45 faraday cloud-init[1125]: Processing triggers for ureadahead (0.100.0-19) ...
[...]
Nov 22 08:31:47 faraday cloud-init[1125]: Processing triggers for ureadahead (0.100.0-19) ...
[...]
Nov 22 08:32:32 faraday systemd[1]: Starting Stop ureadahead data collection...
Nov 22 08:32:32 faraday systemd[1]: Stopping Read required files in advance...
Nov 22 08:32:32 faraday systemd[1]: Started Stop ureadahead data collection.
Nov 22 08:32:32 faraday ureadahead[474]: ureadahead:events/fs/open_exec/enable: Ignored relative path

So I wonder if cloud-init has changed something here that causes ureadahead from starting the indexing of files, or whether this is something that has changed in the cloud image itself (from CPC) or in Ubuntu itself.

[Ryan Harper (raharper)]

curtin does not do any read-ahead configuration;

[Scott Moser (smoser)]

cloud-init's only interaction with ureadahead is in its postinst [1] where it disables ureadahead per bug 499520.

curtin has no interaction with ureadahead.

ureadahead gets invoked via dpkg triggers. I'm not exactly sure what it triggers off of. likely one of the packages installed or updated triggered that.

--
[1] https://git.launchpad.net/cloud-init/tree/debian/cloud-init.postinst?h=ubuntu/devel

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.