[SRU] Set the default IO scheduler to CFQ in Kubuntu Trusty

[Andy Whitcroft]

On Thu, Oct 16, 2014 at 04:23:36PM +0200, Rohan Garg wrote:
> > A consistent kernel and performance expectations across Ubuntu is also
> > worthwhile. I don't want someone screw up database/VM/etc. workloads
> > benchmarks simply
> > because they happen to have kubuntu-desktop installed or left around
> 
> Are we honestly optimizing for benchmarks now? I'd rather optimize for
> a good user experience, which in the case of Kubuntu requires the use
> of CFQ. I couldn't care less about
> random-news-site-running-random-benchmarks.

For clarity this was not not changed recently, deadline has been the
default scheduler for at least the last two LTS releases, 2.5+ years.
It was changed to fix apparent user experience issues under high disks
loads, such as greying out windows and unresponsive shells.

The change was made after these user reports and only after positive
testing there _and_ benchmarking results also showed advantage to a number
of server workloads.

A similar level of care should be applied before any additional change.

-apw