cvs commit: src/sys/net if_ethersubr.c
ru at freebsd.org
Sun Jul 3 01:07:46 GMT 2005
On Mon, Feb 14, 2005 at 11:13:13AM -0800, Sam Leffler wrote:
> >>This also has the potential to noticeably
> >>affect performance so I think a better solution is needed.
> >Here are my thoughts. On a typical input path, there will be
> >either one or zero mtags, one if driver provided us with the
> >VLAN mtag, so effectively we replaced "ifp->if_nvlans" with
> >"m_tag_first(m) != NULL", and this doesn't look like a huge
> >performance downgrade to me, if at all.
> The intent was/is that if_nvlans be the definitive check for whether or
> not one should inspect the tag chain for vlan tags. This effectively
> renders that assumption invalid. I think it would better to discard
> these frames in the driver rather than allocate a tag, pass it up, then
> discard it in ether_demux. I think you could encapsulate the check in
I said this before: vlan(4) is not the only consumer of VLAN
frames in FreeBSD. VLAN frames are also accepted by ng_vlan(4),
so using the vlan(4)-specific if_nvlans to decide whether we
should accept VLAN frames (in the driver) just isn't appropriate.
ru at FreeBSD.org
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