Re: multiple rx/tx rings and interrupt delivery on newer nics

[Darren Reed <darrenr%fastmail.net@localhost>]

Sepherosa Ziehau wrote:
> On Thu, Jun 14, 2007 at 3:05 PM, Darren Reed <darrenr%fastmail.net@localhost> 
> wrote:
> > Allen Briggs wrote:
> >>
> >> ...
> >> Different hardware has different kinds of packet classification
> >> for incoming packets and probably different kinds of scheduling
>
> M$ defined two standard classification of incoming packets.  Intel has
> several extension (like use addr/port tuple for UDP packets) in their
> pcie NICs, however, I don't think it will get widely deployed.  As
> about the multi-tx queues, AFAIK, all NICs support multi-tx queue
> provided some mechanism to make all TX queues use same priority.

I disagree.

Everyone that wants to sell a NIC for use wit virtualisation is
going to add support for delivery into rings based on IP address.


The latest releases of Solaris that you can download (Solaris
Express Community Edition - not an officially supported product)
can make full use of these NIC features for either queueing
packets up for zones or applications. It'll be in the next
"release" of OpenSolaris. You can be sure that if Linux does
not have something like that now, it will "soon" and the same
for Microsoft. NetBSD can sit around, look at the ceiling,
whistle dixie and pretend that it isn't relevant but nothing
is going to stop the others striving to be "better".

Intel isn't adding these features because people don't want
them or won't use them, if anything it is the exact opposite.
They've got a single 10GB NIC and would like to turn that into
10 virtual 1GB NICs, etc.

I can easily see this feature being used for routing (lets give
all port 80 traffic its own set of tx/rx rings.) Wouldn't you
rather be able to dedicate a descriptor ring or two for your ssh
traffic than rely on ALTQ and the device driver for priority
delivery? Or maybe you want specific rings for ssh and http
because you're using bittorrent a lot and that uses effectively
random addresses and ports?

This capability will eventually work its way into cheaper NICs,
if only in a very limited fashion, because people will want to
run a virtual guest on the desktop using the motherboard NIC
and to not have to suffer from the virtual guest "flooding"
their NIC.

Darren