svn commit: r313854 - head/sys/cam/ctl

[Edward Tomasz Napierała]

On 0217T1522, Alexander Motin wrote:
> On 17.02.2017 12:24, Edward Tomasz Napierała wrote:
> > On 0217T0522, Alexander Motin wrote:
> >> Author: mav
> >> Date: Fri Feb 17 05:22:58 2017
> >> New Revision: 313854
> >> URL: https://svnweb.freebsd.org/changeset/base/313854
> >>
> >> Log:
> >>   Change the way MaxCmdSN is used.
> >>   
> >>   Before this change MaxCmdSN was reported as CmdSN + delta, that made it
> >>   limit number of requests in transmission from the initiator to target,
> >>   that was pretty useless.  After this change MaxCmdSN limits number of
> >>   requests queued to CTL, i.e. maximal queue depth for the initiator.
> >>   The default limit is 256 outstanding requests per initiator at a time.
> >>   
> >>   This code uses existing cs_outstanding_ctl_pdus counter to track queue
> >>   depth.  It's semantics doen't perfectly match, but close enough to not
> >>   add another counter.  Just don't set the maxtags below 2.
> > 
> > I like the change in principle, but I don't like the gratuitous change
> > of sysctl name.  It will break people's configs.  Could you rename it
> > back?  Thanks!
> 
> But its meaning is different now.  Do you know anybody tuning the old
> sysctl?  I can't imagine who would do it and what for.

Yes.  It's been asked about a few times on forums, and it's documented
in ctl(4).  The new meaning is slightly different, sure, but I'd say
it's very close, except that now it really works :-)