[Openib-windows] RE: [PATCH] use of event log for link up/down msg

[Fab Tillier]

> From: Yossi Leybovich [mailto:sleybo at mellanox.co.il]
> Sent: Monday, December 12, 2005 11:40 PM
> 
> > From: Fab Tillier [mailto:ftillier at silverstorm.com]
> > Sent: Monday, December 12, 2005 9:52 PM
> >
> > Hi Yossi,
> >
> > > From: Yossi Leybovich [mailto:sleybo at mellanox.co.il]
> > > Sent: Sunday, December 11, 2005 8:23 AM
> > >
> > > I create patch that enable to log port up\down events to
> > > the log viewer.
> > > I add msg file to the repository.
> > > In the near future I will send patch that will add more massages to
> > > the log viewer(I will also use the NDIS_ERROR_CODE  defines from
> > > ndis.h)
> >
> > I don't see much value in reporting events that are reported
> > through the link state of the adapter - the adapter icon will
> > show whether the link is up or not via the cable unplugged
> > icon.  The error log should be used only for errors.
> 
> I follow the behavior of regular NICs.
> For example:(from my local machine after I pull the cable out)
> Error Event
> Adapter Intel(R) PRO/100 S Desktop Adapter: Adapter Link Down
> 
> Info Event
> Adapter Intel(R) PRO/100 S Desktop Adapter: Adapter Link Up
> 
> I also saw this behavior in other Nics (broadcom ....), you can try it
> yourself.

There are no events generated on my laptop for this.  Even if there were, a
history of the link going up and down every few seconds doesn't tell you much
beside the fact that there's something wrong.  An error, on the other hand, will
tell the user exactly why the connectivity is broken.

On some of my servers, the Broadcom driver reports the link speed along with the
link up event, which might be useful.

> We also got comment from customers that they would like to see these
> events.(They claim that this is a requirment for NICs drivers)

If it was a requirement, NDIS would log the event itself rather than requiring
every driver to implement it.

I based my comments on the DDK docs:

"Logging an I/O error at every possible opportunity is not particularly helpful
to users either, so a miniport driver should log only critical I/O errors that
can help a user or system administrator to debug a network failure for which the
NIC is responsible on a particular machine or a configuration resource conflict
discovered during driver initialization."

> Moreover I think that it good that these event will be logged so we can
> track the IPoIB behavior.

I think it's much more valuable to track errors.  Who cares if the link goes up
and down repeatedly if there's an error indicating why the adapter failed and is
getting reset.  The up/down events only pollute the event log unless they can
carry additional information.

> So I would appriciate if we keep reporting these events .

Can we attach something useful to the log, like the link width and rate when the
link goes up?  Just saying the link is up isn't all that useful.  Additional
data would be great here (like broadcom did).  Perhaps they use
NdisWriteEventLogEntry or have many log messages defined?

- Fab