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

[Dimitri John Ledkov]

On 14 October 2014 12:24, Jonathan Riddell <jr at jriddell.org> wrote:
> On Mon, Oct 13, 2014 at 11:54:54PM +0100, Dimitri John Ledkov wrote:
>> Given that essentially lowest priority is requested under CFQ,
>> equivalent result should be possible to achieve with cgroups
>> containment.
>> Specifically by limiting CPU (cpu.shares set to 100 ~= 1/10 of the
>> default 1024) and/or IO weight (blkio.weight) and bandwidth
>> (blkio.throttle.read_bps_device / blkio.throttle.write_iops_device) of
>> the baloo process. This would then be a scheduler-independent solution
>> and make baloo a truly capped resources background process.
>
> Whyever should KDE software be rewritten to deal with Ubuntu altering
> the upstream defaults of Linux?  Fix Unity.
>

I'm merely proposing to set cgroups stanzas in the upstart system or
session job that spawn that particular process.

I haven't mentioned Unity in no point, but rather that deadline
scheduler outperforms CFQ in variety of workloads,
and thus there are users out there choosing there. Imho the default
kernel config choice here is correct for the diverse
workloads Ubuntu is subject to.

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
on their system. And such a high level component as baloo shouldn't
make such low level assumptions
about the kernel config, even if adjustable at runtime. If that's
true, I demand kernel config to be optimised for Emacs elisp virtual
machine since clearly nothing else should matter!

-- 
Regards,

Dimitri.