Il giorno 05 mar 2017, alle ore 16:16, Jens Axboe [off-list ref] ha =

scritto:

=20
On 03/04/2017 09:01 AM, Paolo Valente wrote:

quoted

We tag as v0 the version of BFQ containing only BFQ's engine plus
hierarchical support. BFQ's engine is introduced by this commit, =

while

quoted

hierarchical support is added by next commit. We use the v0 tag to
distinguish this minimal version of BFQ from the versions containing
also the features and the improvements added by next commits. BFQ-v0
coincides with the version of BFQ submitted a few years ago [1], =

apart

quoted

from the introduction of preemption, described below.
=20
BFQ is a proportional-share I/O scheduler, whose general structure,
plus a lot of code, are borrowed from CFQ.

=20
I'll take a closer look at this in the coming week.

ok

But one quick
comment - don't default to BFQ. Both because it might not be fully
stable yet, and also because the performance limitation of it is
quite severe. Whereas deadline doesn't really hurt single queue
flash at all, BFQ will.
=20

Ok, sorry.  I was doubtful on what to do, but, to not bother you on
every details, I went for setting it as default, because I thought
people would have preferred to test it, even from boot, in this
preliminary stage.  I reset elevator.c in the submission, unless you
want me to do it even before receiving your and others' reviews.

Generally, I think that sort of logic should go into a udev rule. If
a device is rotational it should default to BFQ once the dust has
settled.
=20

ok

Looking forward for your feedback,
Paolo

--=20
Jens Axboe
=20