Freebsd IP Forwarding performance (question, and some info) [7-stable, current, em, smp]

Kip Macy kip.macy at
Tue Jul 8 07:32:10 UTC 2008

On Mon, Jul 7, 2008 at 6:22 PM, Paul <paul at> wrote:
> I read through the IGB driver, and it says 82575/6 only...  which is the new
> chip Intel is releasing on the cards this month 2 port
> and october 4 port, but the chips are on some of the motherboards right now.
> Why can't it also use the 82571 ? doesn't make any sense.. I haven't tried
> it but just browsing the driver source
> doesn't look like it will work.

The igb driver has been written to remove a lot of the cruft that has
accumulated to work around  deficiencies in earlier 8257x hardware.
Although it supports "legacy" descriptor handling it has a new mode of
descriptor handling that is ostensibly better. I don't have access to
the data sheets for pre-zoar hardware so I'm not sure what it would
take to support multiple queues on that hardware.


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