Status of Multi-Queue (RSS) Support in -CURRENT

Kip Macy kip.macy at
Mon Jul 21 21:27:15 UTC 2008

On Mon, Jul 21, 2008 at 10:36 AM, David Christensen
<davidch at> wrote:
> I'm working on implementing multi-queue support for a 10Gb
> device on FreeBSD and I wanted to find out the current state
> of the OS with regards to supporting this.  It seems that
> support for multiple receive queues can be done today since
> most of the routing is done in hardware but the transmit
> side is a different story.  I've seen some things in the
> cxgb driver that suggest changes to the OS (such as a
> m_pkthdr.rss_hash field) but I don't see any OS code to
> back that usage model up.  What's the state of the art
> in multi-queue support for FreeBSD?

Unfortunately nothing has gone in yet. Robert has a prototype
interface and I *think* that he may have come around to accepting my
approach. The right way to integrate QoS and multi-queue cleanly isn't
100% obvious.

I think it isn't unreasonable to expect that the new interfaces will
go in in time for 7.2 but 7.1 is basically impossible at this point
given that the freeze will be happening in the next month.


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