[LSF/MM TOPIC] Two blk-mq related topics

[James Bottomley]

On Mon, 2018-01-29 at 14:00 -0700, Jens Axboe wrote:
> On 1/29/18 1:56 PM, James Bottomley wrote:
> > 
> > On Mon, 2018-01-29 at 23:46 +0800, Ming Lei wrote:
> > [...]
> > > 
> > > 2. When to enable SCSI_MQ at default again?
> > 
> > I'm not sure there's much to discuss ... I think the basic answer
> > is as soon as Christoph wants to try it again.
> 
> FWIW, internally I've been running various IO intensive workloads on
> what is essentially 4.12 upstream with scsi-mq the default (with
> mq-deadline as the scheduler) and comparing IO workloads with a
> previous 4.6 kernel (without scsi-mq), and things are looking
> great.
> 
> We're never going to iron out the last kinks with it being off
> by default, I think we should attempt to flip the switch again
> for 4.16.

Absolutely, I agree we turn it on ASAP.  I just don't want to be on the
receiving end of Linus' flamethrower because a bug we already had
reported against scsi-mq caused problems.  Get confirmation from the
original reporters (or as close to it as you can) that their problems
are fixed and we're good to go; he won't kick us nearly as hard for new
bugs that turn up.

James