[ovs-discuss] Early addition of flows in the kernel.

Jesse Gross jesse at nicira.com
Tue Oct 13 04:21:40 UTC 2015


Please don't drop the mailing list or top post.

Yes. Please see here for more information on the design of OVS:
http://openvswitch.org/support/papers/nsdi2015.pdf

On Mon, Oct 12, 2015 at 6:30 PM, jimson jimson <jimsonchacko at gmail.com> wrote:
> You mean to say one user space flow can result in many in the kernel?
> ________________________________
> From: Jesse Gross
> Sent: ‎13-‎10-‎2015 05:37 AM
> To: jimson chacko
> Cc: discuss at openvswitch.org
> Subject: Re: [ovs-discuss] Early addition of flows in the kernel.
>
> On Mon, Oct 12, 2015 at 5:17 AM, jimson chacko
> <jimsonchacko at gmail.com> wrote> Hi,
>>
>> As per my understanding, OVS inserts the flow in the kernel when an
>> exception packet is handled by the vswitchd (ofcourse when matching flow
>> is
>> present in the vswitchd).
>>
>> Is it possible to push the flow into the kernel as soon as the flow gets
>> added to vswitchd ? This enables in avoiding the exception mechanism and
>> hence faster processing.
>
> No.
>
>> Can you briefly let me know why the design was kept so ?
>
> It's not possible to do in a general and efficient manner. The flows
> kept by the kernel are significantly simpler than the ones in
> userspace to make them easier to process. The consequence is that they
> are less expressive and you can potentially need a lot more of them to
> cover the entire space, which is prohibitively expensive.



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