Re: [PATCH v3 18/21] nvme: Update CCR completion wait timeout to consider CQT

[Randy Jennings]

On Thu, Feb 19, 2026 at 11:25 PM Hannes Reinecke <hare@xxxxxxx> wrote:
>
> On 2/20/26 03:01, Randy Jennings wrote:
> > Hannes,
> >
> >> (ctrl->kato * 1000) + ctrl->cqt
> > As Mohamed pointed out, we have already received a response from a CCR
> > command.  The CCR, once accepted, communicates the death of the
> > connection to the impacted controller and starts the cleanup tracked
> > by CQT.  So, no need to wait for the impacted controller to figure out
> > the connection is down.
> >
> > The max(cqt, kato) was just to give some wait time that should allow
> > issuing a CCR again from a different controller (in case of losing
> > communication with this one).  It certainly does not need to be longer
> > than cqt (and it should be no longer than the remaining duration of
> > time-based retry; that should get addressed at some point).  I cannot
> > remember why kato (if larger; I expect it would be smaller) made sense
> > at the time.
> >
> Because we have to wait for the AEN, at which point KATO comes into
> play yet again.
> So max(CQT, KATO) is the appropriate waiting time for that.
I see your point.  It could take ~KATO time for the AEN to show up after
the CCR operation finishes.  Technically true.  However, if responses
are taking KATO time to get back to the host, I think would rather retry
on a more healthy link.

Sincerely,
Randy Jennings