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

[junaid khalid]

Hi,

we are talking about the recv failed problem (system at br0: recv failed (No
buffer space available)).

It cannot be the problem with the controller since the flows are already
written in the userspace. We have very limited rate (400 pkts/sec)  while
writing the flows and the controller can handle this rate easily.

On Wed, Apr 25, 2012 at 10:31 AM, Ben Pfaff <blp at nicira.com> wrote:

> 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?
>
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