eatmydata package for centos

[Vladimir Kozhukalov]

We need this package to be installed on the master node in order to make it possible to run debootstrap with disabled fsync-s. It could make image build process much faster but more dangerous. At least it could be useful for test/development environments.

This package is not a part of Fedora yet https://bugzilla.redhat.com/show_bug.cgi?id=1007619 But it is a part of Suse https://build.opensuse.org/package/show/openSUSE:Factory/eatmydata

[Alexei Sheplyakov (asheplyakov)]

Actually it's more useful to disable ext4 journal while building the image (and re-enable it afterwards)

[Alexander Gordeev (a-gordeev)]

Alexei Sheplyakov, do you know what will be expected amount of building time speed up?

[Alexei Sheplyakov (asheplyakov)]

Building 6.0 ISO (which involves creating IBP images) on an EXT4 filesystem without a journal yield 2x speedup.

Basically fsync on ext[34] triggers journal commit (at least in data=ordered mode) so fsync'ing a single file is equivalent to sync'ing the whole filesystem (see http://thunk.org/tytso/blog/2009/03/15/dont-fear-the-fsync for more details). That's why fsync is so expensive on ext[34]. There's to way to solve the problem: 1) avoid/eliminate fsync calls, 2) make fsync performance reasonable by turning off journal (or using a less aggressive journaling mode such as data=writeback). Both these methods are essentially equivalent (and both trade safety for speed). However the 2nd one does not require any additional software.

[Aleksander Mogylchenko (amogylchenko)]

@Vladimir, please evaluate solution provided by Alexei and let us know if you still need additional software (with some proofs).

[Aleksandr Didenko (adidenko)]

4 weeks without updates. Changing Incomplete to Invalid.