Comment 23 for bug 1008400

In my opinion I also agree to use deadline scheduler for server kernel which is also the same problem on the 4.15 kernel, if a server kernel would still exist.

Under trusty we generally saw good performance with deadline scheduler and on a recent SSD based deployment with 4.15 I noticed a large performance regression for random IO until we reverted to deadline. You could argue that the scheduler can be changed at any time but on the contrary I would assume more general suitable parameters from a server distro vs a desktop distro.
My larger problem is that this change was seemingly done via https://kernel.ubuntu.com/git/ubuntu/ubuntu-zesty.git/commit/?id=af80b83a2b6184fea27f050948146fcd9a28070d by a test based on kernel compiles etc, which to be honest, is not a standard server use case. Apart from the issue that I could not spot any documentation on the release notes that this has changed. If this has been documented and simply missed it, then please ignore this comment. But now I'm wondering what else has changed now.