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    SubjectRe: [GIT PULL] Block pull request for- 4.11-rc1
    On 2017.02.22 at 11:44 -0700, Jens Axboe wrote:
    > On 02/22/2017 11:42 AM, Linus Torvalds wrote:
    > > On Wed, Feb 22, 2017 at 10:26 AM, Linus Torvalds
    > > <torvalds@linux-foundation.org> wrote:
    > >>
    > >> And dammit, IF YOU DON'T EVEN KNOW, WHY THE HELL ARE YOU ASKING THE POOR USER?
    > >
    > > Basically, I'm pushing back on config options that I can't personally
    > > even sanely answer.
    >
    > I got that much, and I don't disagree on that part.
    >
    > > If it's a config option about "do I have a particular piece of
    > > hardware", it makes sense. But these new ones were just complete
    > > garbage.
    > >
    > > The whole "default IO scheduler" thing is a disease. We should stop
    > > making up these shit schedulers and then say "we don't know which one
    > > works best for you".
    > >
    > > All it does is encourage developers to make shortcuts and create crap
    > > that isn't generically useful, and then blame the user and say "well,
    > > you should have picked a different scheduler" when they say "this does
    > > not work well for me".
    > >
    > > We have had too many of those kinds of broken choices. And when the
    > > new Kconfig options get so confusing and so esoteric that I go "Hmm, I
    > > have no idea if my hardware does a single queue or not", I put my foot
    > > down.
    > >
    > > When the IO scheduler questions were about a generic IO scheduler for
    > > everything, I can kind of understand them. I think it was still a
    > > mistake (for the reasons outline above), but at least it was a
    > > comprehensible question to ask.
    > >
    > > But when it gets to "what should I do about a single-queue version of
    > > a MQ scheduler", the question is no longer even remotely sensible. The
    > > question should simply NOT EXIST. There is no possible valid reason to
    > > ask that kind of crap.
    >
    > OK, so here's what I'll do:
    >
    > 1) We'll kill the default scheduler choices. sq blk-mq will default to
    > mq-deadline, mq blk-mq will default to "none" (at least for now, until
    > the new scheduler is done).

    But what about e.g. SATA SSDs? Wouldn't they be better off without any
    scheduler?
    So perhaps setting "none" for queue/rotational==0 and mq-deadline for
    spinning drives automatically in the sq blk-mq case?

    --
    Markus

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