rpc.kstatd: Remote Kstat Access Service [PSARC/2008/502 FastTrack timeout 08/13/2008]

[James Carlson]

Darren Reed writes:
> Can someone point me to where the stability of kstats currently
> exported by kstats(1m) is defined for those that are "stable"?
> 
> Not being able to easily see anything on a man page...

There's no one place that this is collected.  As one previously-
mentioned example, there's PSARC 1997/198 (plus the 2003/581 follow-on
case).

>  From what I can see, rpc.rstatd already makes extensive use of
> kstats to serve disk/cpu information and it would seem to me that
> its use of those statistics is equally as evil as the proposed new
> use by rpc.kstatd, in which case, we have a precedent for allowing
> the architectural model that rpc.kstatd uses internally.

The BIG difference is that rpc.rstatd doesn't provide access to
remote-user-specified kstats.  Instead, it happens to use some
internal (same consolidation) kstats as part of its internal
implementation.

If someone were to modify those kstats, he'd have to update rpc.rstatd
to make sure he didn't break it.  But he wouldn't have to chase down
any of the consumers of the service that rpc.rstatd supplies, because
those consumers neither know nor care that the internal implementation
uses kstats.

> The only difference being the definition of the rstat protocol
> being a bit tighter than just "any old kstats."

It's a huge difference.  It's the difference between "made stable" and
"not stable at all."

> That said...
> 
> Having looked at the kstat.x file in the case directory, it becomes
> apparent that this project isn't exporting just any and all statistics,
> but rather a small number of statistics.

Can you expand on that?  I don't see how that follows from the kstat.x
code.  That code appears to return kstats based on the names provided
by a remote user.

-- 
James Carlson, Solaris Networking              <james.d.carlson at sun.com>
Sun Microsystems / 35 Network Drive        71.232W   Vox +1 781 442 2084
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