[crossbow-discuss] [networking-discuss] dlstat for data link statistics

[James Carlson]

Shrikrishna Khare writes:
> To address Jim's concern regarding how dladm would be transitioned: 
> dladm man page is changed to declare that show-usage, 
> show-{link,aggr,vnic} -s is obsolete. Those commands would continue to 
> work for 'a while' even after dlstat is integrated (would post exact 
> timeline later).

Can I have a ballpark?  Is it more like a month from now or a year?

The reason I ask is that I have my *own* "show-bridge" subcommand that
I have to look after.  If this is coming soon, then I'll need to plan
for it.  If it's only in a "Crossbow Phase 2" (or some such) ON
integration much further down the road, then I'll need to plan around
it.

Thanks for adding the details on dladm; this helps.

> >    * It's not clear to me why we need both "kstat mode" and "full-screen"
> >      mode.  If we do need to keep both, I'd be inclined to use "-k" for
> >      kstat mode rather than "-v".
> Am fine with -k as well (Changed in the man page).

I'm a little confused by kstat mode.  What's the usage of it?  (Don't
we already have a usable kstat(1M) command ... ?)

>      The following subcommands are supported:

I assume the majority of these require no special privileges
... right?  If they do require privileges, then that should be noted.

>      dlstat reset [link[,...]]
> 
> 	 Resets the link statistic counters for the specified link(s).
> 	 If invoked without specifying any link, it resets statistics
> 	 for all the links.

I'm nervous about this one.

In general, I think that resetting statistics is a Bad Thing.  It's in
violation of the Counter semantics for SNMP, which means that we'd at
least have to compute deltas in the kernel for use by this command (so
that we can continue to export non-resetting statistics for things
that require them).  It also makes a fundamental assumption that
there's only one system administrator, and while that's probably true
of a laptop, it's certainly not true of a large system.  Allowing
statistics to be reset results in surprise for other administrators.

What happens if I do "dlstat reset" while someone else is running one
of the "-i" interval variants of the command?  Does that other user
see a large negative delta or something else?

Part of the point of those "interval" options is to avoid the need for
ever resetting the statistics.  Why is reset necessary?

>      dladm scan-wifi [[-p] -o field[,...]] [wifi-link]

I think this one might need a little more examination, or at least
some explanation.

The "scan-wifi" subcommand actually has two distinct components that
are (a bit unfortunately) rolled into one command.

One part is clearly an administrative command -- telling the driver to
perform a scan right now to interrogate and refresh its list of APs in
range.  The other part is displaying the current scan results.

That latter bit doesn't seem at all like administration or
configuration to me.  It's "status" information, which I think ought
to belong in a status-reporting command like "dlstat."

There are probably also a fair number of read-only linkprop values
that are actually "status" information and not "configuration," making
this split even less obvious.  "Some" status is still in dladm, but
"other" status information is moving to dlstat.

In any event, I think the line between what goes into dladm and dlstat
isn't too clear because of the history.  It'd be good to have a clear
model so that users don't end up confused.  (As they often do when we
split commands apart -- for example, zoneadm and zonecfg or svcadm and
svccfg.  Even with a fairly clear technical model, users can be
baffled.)

-- 
James Carlson, Solaris Networking              <james.d.carlson at sun.com>
Sun Microsystems / 35 Network Drive        71.232W   Vox +1 781 442 2084
MS UBUR02-212 / Burlington MA 01803-2757   42.496N   Fax +1 781 442 1677