[ovs-discuss] ovs-vsctl looping

[jinho hwang]

On Thu, Jun 13, 2013 at 1:58 PM, jinho hwang <hwang.jinho at gmail.com> wrote:

>
> On Thu, Jun 13, 2013 at 1:26 PM, Ben Pfaff <blp at nicira.com> wrote:
>
>> On Thu, Jun 13, 2013 at 01:17:39PM -0400, jinho hwang wrote:
>> > On Thu, Jun 13, 2013 at 12:16 PM, Ben Pfaff <blp at nicira.com> wrote:
>> >
>> > > On Thu, Jun 13, 2013 at 10:37:49AM -0400, jinho hwang wrote:
>> > > > I am new to ovs. I am trying to set up userspace switch using
>> > > > INSTALL.userspace. There are many commands to add bridge and
>> interfaces
>> > > > using ovs-vsctl, but ovs-vsctl does not return (infinite loop). How
>> do I
>> > > > have to run these commands? Just ctrl-c is ok? I may not have a good
>> > > > understanding of the system yet. If you can refer me to any good
>> > > > documentation related to this, it would be appreciated as well.
>> > >
>> > > Is ovs-vswitchd running?
>> > >
>> >
>> > Thanks, Ben.
>> >
>> > I have figured out how the system works now. I thought ovs-vsctl does
>> not
>> > return to the user, but it was controlled by ovs-vswtichd that signals
>> to
>> > close. Like you said, my fault was that I did not run ovs-vswitchd
>> > properly.
>> >
>> > A couple of more questions if you can provide some more information:
>> >
>> > 1. Logging:
>> > ovs-aptctl shows all INFO in file column, but I can not find any file
>> > logging messages. Not in /var/log and in /usr/local/var/log/
>> > Is there any global knob I should control?
>>
>> Use --log-file, see the manpage for details.
>>
>> > 2. Userspace datapath:
>> > - Does this mean netdev is used by datapath?
>>
>> Yes.
>>
>> > - If so, how can I query stat information of datapath? Is there even
>> one to
>> > query? I want to see something like "ovs-dpctl show br0", if there is
>> one.
>>
>> You can use "ovs-appctl dpif/show".
>>
>> > - What are the limitations if I use userspace datapath? I know
>> performance
>> > can not be good, and some functionalities (tunneling) may not work.
>> Right?
>>
>> Yes.
>>
>
> Thanks again, Ben.
>
> Sorry to bother you, but I have follow-up questions:
>
> 1. Can you interpret these messages?
> 2013-06-13T17:52:20Z|00144|*dpif_netdev*|ERR|error receiving data from
> em1: Message too long
> 2013-06-13T17:52:27Z|00145|netdev|INFO|Dropped 1214 log messages in last
> 12 seconds (most recently, 0 seconds ago) due to excessive rate
> 2013-06-13T17:52:27Z|00146|netdev|INFO|--------trace:
> lib/netdev.c-netdev_recv(419)
>
> - Why is dpif_netdev called?
>
-> It turns out that dpif_netdev is the datapath routine that calls
netdev.c for data. I can confirm that bridge.c makes this happens to make
netdev class for "netdev" in a dummy fashion.

- Is it a part of userspace netdev?

>
> -> Yes,

>
> 2. I am not very clear on where I receive packets and route them where? I
> am trying to read code now, but I am not very sure.
>
> - Can you pin point where netdev receives packets and forward them to
> where?
>
-> It comes to the netdev_recv function to call device-specific read, and
in dpif_netdev_run function, a received packet goes to dp_netdev_port_input
for routing. Then, depending on dp_netdev_lookup_flow result, the packet is
switched to another place(dp_netdev_execute_actions) or to userspace as an
upcall which hangs to dp->queues structure.


> - Also, Do flows in the table not call upcall? Or all the traffic go to
> the ovs-switchd?
>
-> Clarified above.

>
> Thank you,
>
> Jinho
>

Self answered. Please correct me if I am wrong. Thanks for the help! - Jinho
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