HEADS UP: E1000 networking changes in STABLE/7.1 RELEASE

Jack Vogel jfvogel at gmail.com
Thu Aug 14 04:35:45 UTC 2008

On Wed, Aug 13, 2008 at 8:13 PM, Paul <paul at gtcomm.net> wrote:
> Hi Jack.  Will the em driver ever support the multiple hardware queues of
> the 82571 or are we just stuck with the standard em driver?
> Has there been any significant change in the em driver itself ?
> I have a feeling that the 82571 should be in the igb driver but for some
> reason it isn't. I am curious because we have a LOT of 4 port 82571 PCI-E
> cards and they are not cheap.  :]

Hey Paul,

   You are right, quad port cards aren't cheap, Intel has sold them
even back in a
PCI-X based system. And the one you are talking about was released since I
have been in this job, so pretty new :) However, they will never
support multiple
queues, the reason being that in order to do this you need multple MSI vectors,
in other words, MSIX. Still, they are very handy, they do support MSI, but just
one per interface.  Oh, and I debated about where to make the cutoff line on the
em/igb split and decided the best thing to do was to follow Linux. The biggest
difference between the two drivers is that those in the igb use a
different descriptor
format, called 'advanced descriptors'.

   The split does NOT mean that em is now fixed. Quite the contrary,
the em driver
that was just MFC'd into STABLE has support for what I think is going to be the
coolest new consumer adapter out there, called 82574, code name Hartwell, and
also for ICH10. Both these two new interfaces have IEEE 1588 Precision Time
Protocol support, something that is becoming important for networked multimedia
applications. Oh, and Hartwell is the first adapter in the em driver
that actually
does multiqueue, although in a limited fashion, it does MSIX. This
adapter is made
at a lower cost point, but it has really nice features. I only wish
the new motherboard
that I bought had them rather than ICH9 but oh well :) I predict they
are going to
be selling like hotcakes before the end of year.

I will continue to share fixes between the em and igb drivers as they
are applicable.
I still think a real legacy driver for the oldest adapters would be a
good idea, just so
they don't get broken by new development, with as many as we support regression
testing is already not being done adequately. I just have not had time
to think about
this yet, it may be coming, it would probably be for everything that
was not PCI Express.

Hope the info was helpful, I'm always happy to answer questions,


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