[ovs-dev] [PATCH 0/2 v3] [RFC] tunnelling: stt: Prototype Implementation

Jesse Gross jesse at nicira.com
Fri Apr 20 00:55:28 UTC 2012


On Thu, Apr 19, 2012 at 5:13 PM, Simon Horman <horms at verge.net.au> wrote:
> On Thu, Apr 19, 2012 at 01:29:08PM -0700, Jesse Gross wrote:
>> On Wed, Apr 18, 2012 at 9:50 PM, Simon Horman <horms at verge.net.au> wrote:
>> >  It seems to me that some changes are needed to the tunneling core code,
>> >  in particular handle_offloads(), to allow GSO skbs to be passed
>> >  unsegmented to STT. Perhaps a new mutable->flags flag is in order?
>>
>> I agree that there definitely needs to be additional information given
>> to the tunneling core to enable it to decide whether or not to emulate
>> offloads.  However, I think the information belongs in tnl_ops instead
>> of mutable->flags since it is shared by all tunnels of a given type.
>
> Thanks, I will look into that.
>
> At this point I am thinking of a single flag to indicate that
> the protocol handler is able to handle GSO skbs. I'll see about preparing
> a patch to implement that. But perhaps a single flag is insufficient
> for some cases?

I think it needs to be a little more sophisticated that that.  In the
cases that where you currently drop the packet due to being
incompatible with STT (such as an extra level of vlan tag, L4 offset
too large, etc.) we should do software segmentation to avoid the need
to offload over STT.  Also not all types of GSO types are supported
over STT (such as FCoE or future ones that don't exist today).
Probably a function to evaluate a packet for offloading is more
appropriate.



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