Re: TSO, SMP and the em driver.

On Fri, Sep 15, 2006 at 10:14:35AM -0400, John Baldwin wrote:
> On Friday 15 September 2006 06:45, Andre Oppermann wrote:
> > Gleb Smirnoff wrote:
> > > On Wed, Sep 13, 2006 at 10:46:22AM -0500, Brooks Davis wrote:
> > > B> On Wed, Sep 13, 2006 at 11:08:44AM -0400, John Baldwin wrote:
> > > B> > On Tuesday 12 September 2006 19:14, Andre Oppermann wrote:
> > > B> > > Mike Tancsa wrote:
> > > B> > > > At 12:43 PM 9/12/2006, Andre Oppermann wrote:
> > > B> 
> > > B> I'm not sure it's worth worrying about with GbE hardware.  Just disable
> > > B> TSO in promiscuous mode.  Where TSO is going to really matter is 10GbE.
> > > B> No supporting TSO in some configurations with GbE doesn't seem like a
> > > B> big deal to me.
> > > 
> > > Yes, makeing TSO and promisc mutually exclusive would be fine.
> > 
> > There is no point in disabling TSO in when the card is in promisc mode.
> > Promisc mode only affects the receive path where TSO doesn't do a thing,
> > it is only used on the send path.
> 
> The real fix is that the network stack including bpf(4) needs to be aware
> of VLANs that aren't stored in the packet data (mtag, mbuf header,
> wherever).  If you fixed bridging and bpf to recoginize VLAN IDs in metadata
> and handle them then em(4) wouldn't need this hack.  Also, if my understanding
> is correct, this hack is really needed for _any_ ethernet driver that supports
> vlan tagging in hardware unless we fix the stack consumers.

I have a patch ready that makes the bridge use the new ether_vlan field
when it gets committed.


Andrew