[ovs-discuss] warning messages regarding buffer space and unknown buffer

[Ben Pfaff]

On Wed, Apr 25, 2012 at 10:28:05AM +0500, junaid khalid wrote:
> On Wed, Apr 25, 2012 at 10:14 AM, Ben Pfaff <blp at nicira.com> wrote:
> 
> > On Wed, Apr 25, 2012 at 09:43:50AM +0500, junaid khalid wrote:
> > > On Tue, Apr 24, 2012 at 9:06 PM, Ben Pfaff <blp at nicira.com> wrote:
> > >
> > > > On Tue, Apr 24, 2012 at 07:02:37PM +0600, junaid khalid wrote:
> > > > > Do you mean the setup of flows in cached flow table in kernel
> > module? We
> > > > > are sending packets after setting up the flows. Therefore, this
> > problem
> > > > > should be in the fast path or in other words, between the
> > ovs-vswitchd
> > > > and
> > > > > kernel module.
> > > >
> > > > You said you have 100,000 flows.  How many packets in each flow?
> > > >
> > > we are generating packets in a round robin fashion, approx. 6 packets per
> > > flow per sec.
> >
> > You might want to increase the flow eviction threshold to 100000 then.
> > See the documentation in ovs-vswitchd.conf.db(5).
> >
> We have also tried that. We set the flow eviction threshold to 100,000 and
> added a periodic print in the kernel module to check the number of entries
> in the flow table in kernel module. We noticed that, although the flow
> table size in userspace is 100,000 (from dump-aggregate command), but the
> flow table size in kernel module increases gradually and the error
> continues to come up till the kernel table is completely filled with 100000
> entries.

I'm not sure what's "the error".  If it's the one about unknown buffers,
then that's probably because you've got some kind of packet loss between
the switch and your controller.  Or your controller can't keep up with
100,000 "packet-in"s in the first 166 ms (1/6 of a second)?

Is the controller in-band?