SRU IO Scheduler in Kubuntu 14.04

[Steve Langasek]

Hi folks,

On Tue, Oct 14, 2014 at 05:08:41PM +0200, Martin Pitt wrote:
> Hello Harald, hello TB,

> Harald Sitter [2014-10-08 17:03 +0200]:
> > I would like to kindly request the TBs input on a possible IO
> > scheduler changing SRU for Kubuntu 14.04.

> I followed the discussion in the other thread (on u-devel@?).

> > As seen in comment #5 of [2] it was suggested to wait until after the
> > release of 14.10 and only then proceed with the SRU. Most Kubuntu devs
> > do not appear to agree with this as being too conservative an
> > approach. The possible fallout is highly limited in impact (could only
> > make some things slower) and scope (only could do so on Kubuntu with
> > HDD).

> I don't agree with the "highly limited in impact", but I do agree with
> the compromise of putting the udev rule into kubuntu-default-settings.
> While this isn't an appropriate long-term solution (i. e. it
> definitively shouldn't be done that way in Utopic or at least not in
> V), I don't know of a more appropriate place for an SRU.

Note that this change is already present in utopic.  Are you asking the
Kubuntu team to revert this?

> > Would the technical board support a swifter resolution of the problem
> > or indeed prefer waiting?

> I think we shouldn't wait with landing that change in -proposed, but
> do it now so that we can start collecting feedback and doing
> measurements on this. This will require quite extensive
> verification/testing on various hardware, which certainly won't be
> done by next week. This should include some positive results for
> KDE+balloo on HDD, confirm that the scheduler isn't changed for
> KDE+balloo on SSD, and that running Unity/zeitgeist with
> kubuntu-default-settings installed doesn't show a significant
> regression (some minor timing changes are acceptable, I think).

I outlined here some additional regression testing that I think needs to be
part of the SRU plan:

  https://lists.ubuntu.com/archives/ubuntu-release/2014-October/003071.html

(with my SRU team hat on)

I agree that we shouldn't wait until utopic releases to start gathering
feedback about such a change.  However, I don't think we'll have sufficient
feedback to *release* such an SRU until well after the utopic release,
regardless of when the package is pushed to -proposed; and since the change
is present in utopic, having it in -proposed is not a blocker for starting
to gather this feedback.

As the Kubuntu team's request specifically concerns asking the TB to
expedite the SRU for this, and the utopic release is next week, I think the
reality here is that the answer is "no", whether by default or otherwise.
With no meeting this week due to folks being out, and the SRU being less
than clear cut, I don't think the TB can possibly make a decision quickly
enough for it to make a difference; and anyway, a vote by the TB agreeing
that the SRU should not be blocked until after the utopic release by no
means guarantees that the SRU team will have time to work on this during
release week.

-- 
Steve Langasek                   Give me a lever long enough and a Free OS
Debian Developer                   to set it on, and I can move the world.
Ubuntu Developer                                    http://www.debian.org/
slangasek at ubuntu.com                                     vorlon at debian.org
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