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

[Harald Sitter]

On Tue, Oct 14, 2014 at 2:07 AM, Scott Kitterman <ubuntu at kitterman.com> 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.
>
> Are you offering to implement this?

Implementation aside, I am not sure this would be a suitable
replacement (someone should check with upstream ;)). From what I
gather the notion is that baloo should index as fast as possible given
resources are available. Throttling through a cgroup containment would
lower the available resources in general, wouldn't it? This is
supposedly why ioniceness was used instead. If nothing is going on the
indexer can work at full speed, while if the user is actually doing
something baloo essentially allows the kernel to IO starve it to allow
the rest of the system to be snappy.

HS