On 12/1/2015 8:08 AM, John W. Linville wrote:
On Tue, Dec 01, 2015 at 04:49:28PM +0100, Hannes Frederic Sowa wrote:
On Tue, Dec 1, 2015, at 16:44, John W. Linville wrote:
On Mon, Nov 30, 2015 at 09:26:51PM -0800, Tom Herbert wrote:
On Mon, Nov 30, 2015 at 5:28 PM, Jesse Gross <je...@kernel.org> wrote:
Based on what we can do today, I see only two real choices: do some
refactoring to clean up the stack a bit or remove the existing VXLAN
offloading altogether. I think this series is trying to do the former
and the result is that the stack is cleaner after than before. That
seems like a good thing.
There is a third choice which is to do nothing. Creating an
infrastructure that claims to "Generalize udp based tunnel offload"
but actually doesn't generalize the mechanism is nothing more than
window dressing-- this does nothing to help with the VXLAN to
VXLAN-GPE transition for instance. If geneve specific offload is
really needed now then that can be should with another ndo function,
or alternatively ntuple filter with a device specific action would at
least get the stack out of needing to be concerned with that.
Regardless, we will work optimize the rest of the stack for devices
that implement protocol agnostic mechanisms.
Is there no concern about NDO proliferation? Does the size of the
netdev_ops structure matter? Beyond that, I can see how a single
entry point with an enum specifying the offload type isn't really any
different in the grand scheme of things than having multiple NDOs,
one per offload.
Given the need to live with existing hardware offloads, I would lean
toward a consolidated NDO. But if a different NDO per tunnel type is
preferred, I can be satisified with that.
Having per-offloading NDOs helps the stack to gather further information
what kind of offloads the driver has even maybe without trying to call
down into the layer (just by comparing to NULL). Checking this inside
the driver offload function clearly does not have this feature. So we
finally can have "ip tunnel please-recommend-type" feature. :)
That is a valuable insight! Maybe the per-offload NDO isn't such a
bad idea afterall... :-)
John
This helps me understand why having a separate ndo op might still be ok.
Thanks for the feedback. I will go back to that model. Also I think I
did finally understand the discussion on using a single 2's compliment
checksum method
for future silicon.
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