[ovs-discuss] [ovs-dev] debugging OVS

[Ben Pfaff]

OK, after looking at all of your results, I am more confused than
ever.

Most of the stats that "ovs-dpctl -s show" reports come from exactly
the same place in the kernel as stats reported by "ifconfig" or in
/sys/class/net/eth1/statistics.  tx_dropped and rx_dropped are among
those.  I can't explain why "ovs-dpctl" reports different numbers.  In
general, I would tend to believe the other sources.

On Fri, Sep 19, 2014 at 02:13:36PM -0400, samantha Andares wrote:
> ovs_version: "2.0.2"
>  
> > Date: Fri, 19 Sep 2014 11:11:03 -0700
> > From: blp at nicira.com
> > To: sam.andares at hotmail.com
> > CC: discuss at openvswitch.org; dev at openvswitch.org
> > Subject: Re: [ovs-dev] debugging OVS
> > 
> > What version of OVS is this?
> > 
> > On Fri, Sep 19, 2014 at 02:02:11PM -0400, samantha Andares wrote:
> > > Hi ben, 
> > >  
> > > zero (0)
> > >  
> > > root at arm:/sys/class/net/eth1/statistics# cat tx_dropped
> > > 0
> > >  
> > > if you want all the stats...
> > > root at arm:/sys/class/net/eth1/statistics# cat *
> > > 0
> > > 0
> > > 2436387
> > > 0
> > > 0
> > > 12
> > > 5
> > > 0
> > > 0
> > > 5
> > > 0
> > > 0
> > > 13880
> > > 0
> > > 4856185
> > > 0
> > > 0
> > > 0
> > > 0
> > > 0
> > > 0
> > > 76248
> > > 0
> > >  
> > > although here's the ovs-dpctl -s show once more:
> > >      port 4: eth1
> > >                 RX packets:13856 errors:5 dropped:12 overruns:0 frame:0
> > >                 TX packets:76282 errors:0 dropped:34299 aborted:0 carrier:0
> > >                 collisions:0
> > >                 RX bytes:2625108 (2.5 MiB)  TX bytes:4552367 (4.3 MiB)
> > >  
> > > thanks for your time
> > >  
> > > sam
> > >  
> > > > Date: Fri, 19 Sep 2014 10:07:52 -0700
> > > > From: blp at nicira.com
> > > > To: sam.andares at hotmail.com
> > > > CC: discuss at openvswitch.org; dev at openvswitch.org
> > > > Subject: Re: [ovs-dev] debugging OVS
> > > > 
> > > > What's in /sys/class/net/eth1/statistics/tx_dropped?
> > > > 
> > > > On Fri, Sep 19, 2014 at 11:40:25AM -0400, samantha Andares wrote:
> > > > > Ben, 
> > > > >  
> > > > > Here is the output of the physical interface
> > > > >  
> > > > > eth1      Link encap:Ethernet  HWaddr 00:0e:c6:88:d2:22
> > > > >           inet6 addr: fe80::20e:c6ff:fe88:d222/64 Scope:Link
> > > > >           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
> > > > >           RX packets:1538 errors:0 dropped:12 overruns:0 frame:0
> > > > >           TX packets:63290 errors:0 dropped:0 overruns:0 carrier:0
> > > > >           collisions:0 txqueuelen:1000
> > > > >           RX bytes:270154 (270.1 KB)  TX bytes:2966862 (2.9 MB)
> > > > > 
> > > > > and you can see there are no dropped count in there!
> > > > >  
> > > > > sam
> > > > >  
> > > > > > Date: Fri, 19 Sep 2014 08:33:27 -0700
> > > > > > From: blp at nicira.com
> > > > > > To: sam.andares at hotmail.com
> > > > > > CC: discuss at openvswitch.org; dev at openvswitch.org
> > > > > > Subject: Re: [ovs-dev] debugging OVS
> > > > > > 
> > > > > > Can you show us the "ovs-dpctl show" output?
> > > > > > 
> > > > > > Thanks,
> > > > > > 
> > > > > > Ben.
> > > > > > 
> > > > > > On Fri, Sep 19, 2014 at 11:30:05AM -0400, samantha Andares wrote:
> > > > > > > hi ben, 
> > > > > > >  
> > > > > > > thanks for your feedback.
> > > > > > >  
> > > > > > > I am getting 100% packets drop.. If problem was with the amount of messages... I presume some would have been going through... as stated in my latest email.... this is specific to when going out on a USB to Ethernet adaptor on a specific hardware (beagle bone board). I am using OVS 2.0 and Ubuntu 14.04. How can we analyse the messages in userspace and why would the message go to userspace... shouldn't it stay in kernel space if it matches a flow and just be forwarded to the outgoing physical port as per the rule is saying? My traffic is simple iperf udp messages.. tried flow of 10MB and 100KB... problem is the same...
> > > > > > >  
> > > > > > > thanks, 
> > > > > > >  
> > > > > > > sam
> > > > > > >  
> > > > > > > > Date: Fri, 19 Sep 2014 08:20:24 -0700
> > > > > > > > From: blp at nicira.com
> > > > > > > > To: sam.andares at hotmail.com
> > > > > > > > CC: discuss at openvswitch.org; dev at openvswitch.org
> > > > > > > > Subject: Re: [ovs-dev] debugging OVS
> > > > > > > > 
> > > > > > > > [dropping mininet-discuss because it is a closed mailing list and I am
> > > > > > > > not a subscriber]
> > > > > > > > 
> > > > > > > > On Thu, Sep 18, 2014 at 05:37:43PM -0400, samantha Andares wrote:
> > > > > > > > > I am getting packets dropped when going out of an OVS bridge. The TX
> > > > > > > > > dropped is increased in ovs-dpctl but not at the physical interface
> > > > > > > > > level (ifconfig).
> > > > > > > > >
> > > > > > > > > Can anyone tell me how to enable some OVS debugging so I can find the
> > > > > > > > > reason to fix that problem?
> > > > > > > > 
> > > > > > > > Do you mean that ovs-dpctl shows the datapath's "drop" count is going
> > > > > > > > up?  If so, the problem is that packets that need attention from
> > > > > > > > userspace are arriving faster than userspace can process them.  The best
> > > > > > > > way to reduce drops is to upgrade to the latest version of Open vSwitch,
> > > > > > > > which is 2.3, because we've spent a lot of time the last few years
> > > > > > > > coming up with ways to reduce the number of packets that have to be sent
> > > > > > > > to userspace.  If you are already using 2.3, then I am surprised that
> > > > > > > > you are seeing lots of drops.  Is there anything unusual about your
> > > > > > > > environment or the traffic that you are using?
> > > > > > >  		 	   		  
> > > > >  		 	   		  
> > >  		 	   		  
>