[ovs-discuss] Question about openvswitch kernel module

Voravit T. voravit at kth.se
Fri Oct 28 23:41:32 UTC 2011

Ok, thanks you very much for your quick response.

Best regards,
Voravit T.

On 10/29/2011 01:35 AM, Ben Pfaff wrote:
> On Sat, Oct 29, 2011 at 01:25:01AM +0200, Voravit T. wrote:
>> I would like to do some experiment with Open vSwitch kernel module.
>> I follow instruction as per INSTALL.Linux to compile and start the
>> switch with two ports and add one flow entry that forwards from one port
>> to the other.
>> When I use ovs-ofctl dump-flows I can see the flow entry that I add but
>> when I use ovs-dpctl dump-flows it gives no output (please see second
>> section in the attached file).
> Flow entries are installed in the kernel flow table (that ovs-dpctl
> dump-flows prints) only when packets arrive.
>> I am wondering if this is normal or it could be some strange behaviour
>> due to the way I have compiled the source code.
>> By the way, is there a test tool that allows me to manage the Open
>> vSwitch kernel module directly without running the database server and
>> the ovs-vswicthd daemon?
> No.
>> In addition, I noticed that there are 255 tables in my system with only
>> the first table (0:classifier) is in used. Is there some way to remove
>> the tables that I don't use?
> The additional tables add an insignificant cost.  There is currently
> no way to turn them off.
>> I also noticed that there is a different flow table structure in Open
>> vSwitch kernel module, using a kind of an array structure (flex_array).
>> The old OpenFlow reference kernel module implementation uses a
>> combination of two lookup tables; one hash and one linear.
>> Does anyone know if there is any performance comparison between these
>> types of lookup structures?
> The newer organization should be faster in common usage.
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